.gitignore

@@ -5,7 +5,5 @@ out/
 .gradle
 build/
 
-.kotlin
-
 
 !gradle-wrapper.jar

dataforge-context/build.gradle.kts

@@ -12,7 +12,7 @@ kscience {
     useCoroutines()
     useSerialization()
     commonMain {
-        api(projects.dataforgeMeta)
+        api(project(":dataforge-meta"))
         api(spclibs.atomicfu)
     }
     jvmMain{

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/actions/AbstractAction.kt

@@ -1,7 +1,5 @@
 package space.kscience.dataforge.actions
 
-import kotlinx.coroutines.flow.launchIn
-import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import space.kscience.dataforge.data.*
 import space.kscience.dataforge.meta.Meta
@@ -21,51 +19,46 @@ internal fun MutableMap<Name, *>.removeWhatStartsWith(name: Name) {
 /**
  * An action that caches results on-demand and recalculates them on source push
  */
-public abstract class AbstractAction<T : Any, R : Any>(
+public abstract class AbstractAction<in T : Any, R : Any>(
     public val outputType: KType,
 ) : Action<T, R> {
 
     /**
      * Generate initial content of the output
      */
-    protected abstract fun DataSink<R>.generate(
-        data: DataTree<T>,
+    protected abstract fun DataSetBuilder<R>.generate(
+        data: DataSet<T>,
         meta: Meta,
     )
 
     /**
-     * Update part of the data set using provided data
-     *
-     * @param source the source data tree in case we need several data items to update
+     * Update part of the data set when given [updateKey] is triggered by the source
      */
-    protected open fun DataSink<R>.update(
-        source: DataTree<T>,
+    protected open fun DataSourceBuilder<R>.update(
+        dataSet: DataSet<T>,
         meta: Meta,
-        namedData: NamedData<T>,
-    ){
-        //by default regenerate the whole data set
-        generate(source,meta)
+        updateKey: Name,
+    ) {
+        // By default, recalculate the whole dataset
+        generate(dataSet, meta)
     }
 
     @OptIn(DFInternal::class)
     override fun execute(
-        dataSet: DataTree<T>,
+        dataSet: DataSet<T>,
         meta: Meta,
-    ): DataTree<R> = if(dataSet.isObservable()) {
-        MutableDataTree<R>(outputType, dataSet.updatesScope).apply {
+    ): DataSet<R> = if (dataSet is DataSource) {
+        DataSource(outputType, dataSet){
             generate(dataSet, meta)
-            dataSet.updates().onEach {
-                update(dataSet, meta, it)
-            }.launchIn(updatesScope)
 
-            //close updates when the source is closed
-            updatesScope.launch {
-                dataSet.awaitClose()
-                close()
+            launch {
+                dataSet.updates.collect { name ->
+                    update(dataSet, meta, name)
+                }
             }
         }
-    } else{
-        DataTree(outputType){
+    } else {
+        DataTree<R>(outputType) {
             generate(dataSet, meta)
         }
     }

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/actions/Action.kt

@@ -1,19 +1,19 @@
 package space.kscience.dataforge.actions
 
-import space.kscience.dataforge.data.DataTree
+import space.kscience.dataforge.data.DataSet
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.misc.DFExperimental
 
 /**
  * A simple data transformation on a data node. Actions should avoid doing actual dependency evaluation in [execute].
  */
-public fun interface Action<T, R> {
+public fun interface Action<in T : Any, out R : Any> {
 
     /**
      * Transform the data in the node, producing a new node. By default, it is assumed that all calculations are lazy
      * so not actual computation is started at this moment.
      */
-    public fun execute(dataSet: DataTree<T>, meta: Meta): DataTree<R>
+    public fun execute(dataSet: DataSet<T>, meta: Meta): DataSet<R>
 
     public companion object
 }
@@ -21,23 +21,18 @@ public fun interface Action<T, R> {
 /**
  * A convenience method to transform data using given [action]
  */
-public fun <T, R> DataTree<T>.transform(
-    action: Action<T, R>,
-    meta: Meta = Meta.EMPTY,
-): DataTree<R> = action.execute(this, meta)
+public fun <T : Any, R : Any> DataSet<T>.transform(action: Action<T, R>, meta: Meta = Meta.EMPTY): DataSet<R> =
+    action.execute(this, meta)
 
 /**
  * Action composition. The result is terminal if one of its parts is terminal
  */
-public infix fun <T, I, R> Action<T, I>.then(action: Action<I, R>): Action<T, R> = Action { dataSet, meta ->
-    action.execute(this@then.execute(dataSet, meta), meta)
-}
+public infix fun <T : Any, I : Any, R : Any> Action<T, I>.then(action: Action<I, R>): Action<T, R> =
+    Action<T, R> { dataSet, meta -> action.execute(this@then.execute(dataSet, meta), meta) }
 
 @DFExperimental
-public operator fun <T, R> Action<T, R>.invoke(
-    dataSet: DataTree<T>,
+public operator fun <T : Any, R : Any> Action<T, R>.invoke(
+    dataSet: DataSet<T>,
     meta: Meta = Meta.EMPTY,
-): DataTree<R> = execute(dataSet, meta)
-
-
+): DataSet<R> = execute(dataSet, meta)
 

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/actions/MapAction.kt

@@ -29,7 +29,6 @@ public class MapActionBuilder<T, R>(
     public var name: Name,
     public var meta: MutableMeta,
     public val actionMeta: Meta,
-    public val dataType: KType,
     @PublishedApi internal var outputType: KType,
 ) {
 
@@ -46,16 +45,19 @@ public class MapActionBuilder<T, R>(
     /**
      * Calculate the result of goal
      */
-    public inline fun <reified R1 : R> result(noinline f: suspend ActionEnv.(T) -> R1): Unit = result(typeOf<R1>(), f)
+    public inline fun <reified R1 : R> result(noinline f: suspend ActionEnv.(T) -> R1) {
+        outputType = typeOf<R1>()
+        result = f;
+    }
 }
 
 @PublishedApi
-internal class MapAction<T : Any, R : Any>(
+internal class MapAction<in T : Any, R : Any>(
     outputType: KType,
     private val block: MapActionBuilder<T, R>.() -> Unit,
 ) : AbstractAction<T, R>(outputType) {
 
-    private fun DataSink<R>.mapOne(name: Name, data: Data<T>, meta: Meta) {
+    private fun DataSetBuilder<R>.mapOne(name: Name, data: Data<T>, meta: Meta) {
         // Creating a new environment for action using **old** name, old meta and task meta
         val env = ActionEnv(name, data.meta, meta)
 
@@ -64,7 +66,6 @@ internal class MapAction<T : Any, R : Any>(
             name,
             data.meta.toMutableMeta(), // using data meta
             meta,
-            data.type,
             outputType
         ).apply(block)
 
@@ -79,15 +80,16 @@ internal class MapAction<T : Any, R : Any>(
             builder.result(env, data.await())
         }
         //setting the data node
-        put(newName, newData)
+        data(newName, newData)
     }
 
-    override fun DataSink<R>.generate(data: DataTree<T>, meta: Meta) {
+    override fun DataSetBuilder<R>.generate(data: DataSet<T>, meta: Meta) {
         data.forEach { mapOne(it.name, it.data, meta) }
     }
 
-    override fun DataSink<R>.update(source: DataTree<T>, meta: Meta, namedData: NamedData<T>) {
-        mapOne(namedData.name, namedData.data, namedData.meta)
+    override fun DataSourceBuilder<R>.update(dataSet: DataSet<T>, meta: Meta, updateKey: Name) {
+        remove(updateKey)
+        dataSet[updateKey]?.let { mapOne(updateKey, it, meta) }
     }
 }
 

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/actions/ReduceAction.kt

@@ -14,7 +14,7 @@ import kotlin.reflect.typeOf
 
 public class JoinGroup<T : Any, R : Any>(
     public var name: String,
-    internal val set: DataTree<T>,
+    internal val set: DataSet<T>,
     @PublishedApi internal var outputType: KType,
 ) {
 
@@ -39,7 +39,7 @@ public class ReduceGroupBuilder<T : Any, R : Any>(
     public val actionMeta: Meta,
     private val outputType: KType,
 ) {
-    private val groupRules: MutableList<(DataTree<T>) -> List<JoinGroup<T, R>>> = ArrayList();
+    private val groupRules: MutableList<(DataSet<T>) -> List<JoinGroup<T, R>>> = ArrayList();
 
     /**
      * introduce grouping by meta value
@@ -54,12 +54,12 @@ public class ReduceGroupBuilder<T : Any, R : Any>(
 
     public fun group(
         groupName: String,
-        predicate: DataFilter,
+        predicate: (Name, Meta) -> Boolean,
         action: JoinGroup<T, R>.() -> Unit,
     ) {
         groupRules += { source ->
             listOf(
-                JoinGroup<T, R>(groupName, source.filterData(predicate), outputType).apply(action)
+                JoinGroup<T, R>(groupName, source.filter(predicate), outputType).apply(action)
             )
         }
     }
@@ -73,7 +73,7 @@ public class ReduceGroupBuilder<T : Any, R : Any>(
         }
     }
 
-    internal fun buildGroups(input: DataTree<T>): List<JoinGroup<T, R>> =
+    internal fun buildGroups(input: DataSet<T>): List<JoinGroup<T, R>> =
         groupRules.flatMap { it.invoke(input) }
 
 }
@@ -85,7 +85,7 @@ internal class ReduceAction<T : Any, R : Any>(
 ) : AbstractAction<T, R>(outputType) {
     //TODO optimize reduction. Currently, the whole action recalculates on push
 
-    override fun DataSink<R>.generate(data: DataTree<T>, meta: Meta) {
+    override fun DataSetBuilder<R>.generate(data: DataSet<T>, meta: Meta) {
         ReduceGroupBuilder<T, R>(meta, outputType).apply(action).buildGroups(data).forEach { group ->
             val dataFlow: Map<Name, Data<T>> = group.set.asSequence().fold(HashMap()) { acc, value ->
                 acc.apply {
@@ -103,7 +103,7 @@ internal class ReduceAction<T : Any, R : Any>(
                 meta = groupMeta
             ) { group.result.invoke(env, it) }
 
-            put(env.name, res)
+            data(env.name, res)
         }
     }
 }

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/actions/SplitAction.kt

@@ -49,7 +49,7 @@ internal class SplitAction<T : Any, R : Any>(
     private val action: SplitBuilder<T, R>.() -> Unit,
 ) : AbstractAction<T, R>(outputType) {
 
-    private fun DataSink<R>.splitOne(name: Name, data: Data<T>, meta: Meta) {
+    private fun DataSetBuilder<R>.splitOne(name: Name, data: Data<T>, meta: Meta) {
         val laminate = Laminate(data.meta, meta)
 
         val split = SplitBuilder<T, R>(name, data.meta).apply(action)
@@ -64,7 +64,7 @@ internal class SplitAction<T : Any, R : Any>(
             ).apply(rule)
             //data.map<R>(outputType, meta = env.meta) { env.result(it) }.named(fragmentName)
 
-            put(
+            data(
                 fragmentName,
                 @Suppress("OPT_IN_USAGE") Data(outputType, meta = env.meta, dependencies = listOf(data)) {
                     env.result(data.await())
@@ -73,12 +73,13 @@ internal class SplitAction<T : Any, R : Any>(
         }
     }
 
-    override fun DataSink<R>.generate(data: DataTree<T>, meta: Meta) {
+    override fun DataSetBuilder<R>.generate(data: DataSet<T>, meta: Meta) {
         data.forEach { splitOne(it.name, it.data, meta) }
     }
 
-    override fun DataSink<R>.update(source: DataTree<T>, meta: Meta, namedData: NamedData<T>) {
-        splitOne(namedData.name, namedData.data, namedData.meta)
+    override fun DataSourceBuilder<R>.update(dataSet: DataSet<T>, meta: Meta, updateKey: Name) {
+        remove(updateKey)
+        dataSet[updateKey]?.let { splitOne(updateKey, it, meta) }
     }
 }
 

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/Data.kt

@@ -41,7 +41,7 @@ public interface Data<out T> : Goal<T>, MetaRepr {
          */
         internal val TYPE_OF_NOTHING: KType = typeOf<Unit>()
 
-        public inline fun <reified T> static(
+        public inline fun <reified T : Any> static(
             value: T,
             meta: Meta = Meta.EMPTY,
         ): Data<T> = StaticData(typeOf<T>(), value, meta)
@@ -69,37 +69,37 @@ public interface Data<out T> : Goal<T>, MetaRepr {
  * A lazily computed variant of [Data] based on [LazyGoal]
  * One must ensure that proper [type] is used so this method should not be used
  */
-private class LazyData<T>(
+private class LazyData<T : Any>(
     override val type: KType,
     override val meta: Meta = Meta.EMPTY,
     additionalContext: CoroutineContext = EmptyCoroutineContext,
-    dependencies: Iterable<Goal<*>> = emptyList(),
+    dependencies: Collection<Goal<*>> = emptyList(),
     block: suspend () -> T,
 ) : Data<T>, LazyGoal<T>(additionalContext, dependencies, block)
 
-public class StaticData<T>(
+public class StaticData<T : Any>(
     override val type: KType,
     value: T,
     override val meta: Meta = Meta.EMPTY,
 ) : Data<T>, StaticGoal<T>(value)
 
 @Suppress("FunctionName")
-public inline fun <reified T> Data(value: T, meta: Meta = Meta.EMPTY): StaticData<T> =
+public inline fun <reified T : Any> Data(value: T, meta: Meta = Meta.EMPTY): StaticData<T> =
     StaticData(typeOf<T>(), value, meta)
 
 @DFInternal
-public fun <T> Data(
+public fun <T : Any> Data(
     type: KType,
     meta: Meta = Meta.EMPTY,
     context: CoroutineContext = EmptyCoroutineContext,
-    dependencies: Iterable<Goal<*>> = emptyList(),
+    dependencies: Collection<Goal<*>> = emptyList(),
     block: suspend () -> T,
 ): Data<T> = LazyData(type, meta, context, dependencies, block)
 
 @OptIn(DFInternal::class)
-public inline fun <reified T> Data(
+public inline fun <reified T : Any> Data(
     meta: Meta = Meta.EMPTY,
     context: CoroutineContext = EmptyCoroutineContext,
-    dependencies: Iterable<Goal<*>> = emptyList(),
+    dependencies: Collection<Goal<*>> = emptyList(),
     noinline block: suspend () -> T,
 ): Data<T> = Data(typeOf<T>(), meta, context, dependencies, block)

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataFilter.kt

@@ -1,89 +0,0 @@
-package space.kscience.dataforge.data
-
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.filter
-import space.kscience.dataforge.meta.Meta
-import space.kscience.dataforge.names.Name
-import kotlin.reflect.KType
-
-public fun interface DataFilter {
-
-    public fun accepts(name: Name, meta: Meta, type: KType): Boolean
-
-    public companion object {
-        public val EMPTY: DataFilter = DataFilter { _, _, _ -> true }
-    }
-}
-
-public fun DataFilter.accepts(data: NamedData<*>): Boolean = accepts(data.name, data.meta, data.type)
-
-public fun <T> Sequence<NamedData<T>>.filterData(predicate: DataFilter): Sequence<NamedData<T>> = filter { data ->
-    predicate.accepts(data)
-}
-
-public fun <T> Flow<NamedData<T>>.filterData(predicate: DataFilter): Flow<NamedData<T>> = filter { data ->
-    predicate.accepts(data)
-}
-
-public fun <T> DataSource<T>.filterData(
-    predicate: DataFilter,
-): DataSource<T> = object : DataSource<T> {
-    override val dataType: KType get() = this@filterData.dataType
-
-    override fun read(name: Name): Data<T>? =
-        this@filterData.read(name)?.takeIf { predicate.accepts(name, it.meta, it.type) }
-}
-
-/**
- * Stateless filtered [ObservableDataSource]
- */
-public fun <T> ObservableDataSource<T>.filterData(
-    predicate: DataFilter,
-): ObservableDataSource<T> = object : ObservableDataSource<T> {
-    override fun updates(): Flow<NamedData<T>> = this@filterData.updates().filter { predicate.accepts(it) }
-
-    override val dataType: KType get() = this@filterData.dataType
-
-    override fun read(name: Name): Data<T>? =
-        this@filterData.read(name)?.takeIf { predicate.accepts(name, it.meta, it.type) }
-}
-
-public fun <T> GenericDataTree<T, *>.filterData(
-    predicate: DataFilter,
-): DataTree<T> = asSequence().filterData(predicate).toTree(dataType)
-
-public fun <T> GenericObservableDataTree<T, *>.filterData(
-    scope: CoroutineScope,
-    predicate: DataFilter,
-): ObservableDataTree<T> = asSequence().filterData(predicate).toObservableTree(dataType, scope, updates().filterData(predicate))
-
-
-///**
-// * Generate a wrapper data set with a given name prefix appended to all names
-// */
-//public fun <T : Any> DataTree<T>.withNamePrefix(prefix: Name): DataSet<T> = if (prefix.isEmpty()) {
-//    this
-//} else object : DataSource<T> {
-//
-//    override val dataType: KType get() = this@withNamePrefix.dataType
-//
-//    override val coroutineContext: CoroutineContext
-//        get() = (this@withNamePrefix as? DataSource)?.coroutineContext ?: EmptyCoroutineContext
-//
-//    override val meta: Meta get() = this@withNamePrefix.meta
-//
-//
-//    override fun iterator(): Iterator<NamedData<T>> = iterator {
-//        for (d in this@withNamePrefix) {
-//            yield(d.data.named(prefix + d.name))
-//        }
-//    }
-//
-//    override fun get(name: Name): Data<T>? =
-//        name.removeFirstOrNull(name)?.let { this@withNamePrefix.get(it) }
-//
-//    override val updates: Flow<Name> get() = this@withNamePrefix.updates.map { prefix + it }
-//}
-//
-

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataSet.kt

@@ -0,0 +1,124 @@
+package space.kscience.dataforge.data
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.emptyFlow
+import kotlinx.coroutines.flow.mapNotNull
+import space.kscience.dataforge.data.Data.Companion.TYPE_OF_NOTHING
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.names.Name
+import space.kscience.dataforge.names.asName
+import space.kscience.dataforge.names.endsWith
+import space.kscience.dataforge.names.parseAsName
+import kotlin.reflect.KType
+
+public interface DataSet<out T : Any> {
+
+    /**
+     * The minimal common ancestor to all data in the node
+     */
+    public val dataType: KType
+
+    /**
+     * Meta-data associated with this node. If no meta is provided, returns [Meta.EMPTY].
+     */
+    public val meta: Meta
+
+    /**
+     * Traverse this [DataSet] returning named data instances. The order is not guaranteed.
+     */
+    public operator fun iterator(): Iterator<NamedData<T>>
+
+    /**
+     * Get data with given name.
+     */
+    public operator fun get(name: Name): Data<T>?
+
+    public companion object {
+        public val META_KEY: Name = "@meta".asName()
+
+        /**
+         * An empty [DataSet] that suits all types
+         */
+        public val EMPTY: DataSet<Nothing> = object : DataSet<Nothing> {
+            override val dataType: KType = TYPE_OF_NOTHING
+            override val meta: Meta get() = Meta.EMPTY
+
+            override fun iterator(): Iterator<NamedData<Nothing>> = emptySequence<NamedData<Nothing>>().iterator()
+
+            override fun get(name: Name): Data<Nothing>? = null
+        }
+    }
+}
+
+public fun <T : Any> DataSet<T>.asSequence(): Sequence<NamedData<T>> = object : Sequence<NamedData<T>> {
+    override fun iterator(): Iterator<NamedData<T>> = this@asSequence.iterator()
+}
+
+/**
+ * Return a single [Data] in this [DataSet]. Throw error if it is not single.
+ */
+public fun <T : Any> DataSet<T>.single(): NamedData<T> = asSequence().single()
+
+public fun <T : Any> DataSet<T>.asIterable(): Iterable<NamedData<T>> = object : Iterable<NamedData<T>> {
+    override fun iterator(): Iterator<NamedData<T>> = this@asIterable.iterator()
+}
+
+public operator fun <T : Any> DataSet<T>.get(name: String): Data<T>? = get(name.parseAsName())
+
+/**
+ * A [DataSet] with propagated updates.
+ */
+public interface DataSource<out T : Any> : DataSet<T>, CoroutineScope {
+
+    /**
+     * A flow of updated item names. Updates are propagated in a form of [Flow] of names of updated nodes.
+     * Those can include new data items and replacement of existing ones. The replaced items could update existing data content
+     * and replace it completely, so they should be pulled again.
+     *
+     */
+    public val updates: Flow<Name>
+
+    /**
+     * Stop generating updates from this [DataSource]
+     */
+    public fun close() {
+        coroutineContext[Job]?.cancel()
+    }
+}
+
+public val <T : Any> DataSet<T>.updates: Flow<Name> get() = if (this is DataSource) updates else emptyFlow()
+//
+///**
+// * Flow all data nodes with names starting with [branchName]
+// */
+//public fun <T : Any> DataSet<T>.children(branchName: Name): Sequence<NamedData<T>> =
+//    this@children.asSequence().filter {
+//        it.name.startsWith(branchName)
+//    }
+
+/**
+ * Start computation for all goals in data node and return a job for the whole node
+ */
+public fun <T : Any> DataSet<T>.startAll(coroutineScope: CoroutineScope): Job = coroutineScope.launch {
+    asIterable().map {
+        it.launch(this@launch)
+    }.joinAll()
+}
+
+public suspend fun <T : Any> DataSet<T>.computeAndJoinAll(): Unit = coroutineScope { startAll(this).join() }
+
+public fun DataSet<*>.toMeta(): Meta = Meta {
+    forEach {
+        if (it.name.endsWith(DataSet.META_KEY)) {
+            set(it.name, it.meta)
+        } else {
+            it.name put {
+                "type" put it.type.toString()
+                "meta" put it.meta
+            }
+        }
+    }
+}
+
+public val <T : Any> DataSet<T>.updatesWithData: Flow<NamedData<T>> get() = updates.mapNotNull { get(it)?.named(it) }

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataSetBuilder.kt

@@ -0,0 +1,165 @@
+package space.kscience.dataforge.data
+
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.meta.MutableMeta
+import space.kscience.dataforge.misc.DFExperimental
+import space.kscience.dataforge.names.Name
+import space.kscience.dataforge.names.isEmpty
+import space.kscience.dataforge.names.plus
+import kotlin.reflect.KType
+
+public interface DataSetBuilder<in T : Any> {
+    public val dataType: KType
+
+    /**
+     * Remove all data items starting with [name]
+     */
+    public fun remove(name: Name)
+
+    public fun data(name: Name, data: Data<T>?)
+
+    /**
+     * Set a current state of given [dataSet] into a branch [name]. Does not propagate updates
+     */
+    public fun node(name: Name, dataSet: DataSet<T>) {
+        //remove previous items
+        if (name != Name.EMPTY) {
+            remove(name)
+        }
+
+        //Set new items
+        dataSet.forEach {
+            data(name + it.name, it.data)
+        }
+    }
+
+    /**
+     * Set meta for the given node
+     */
+    public fun meta(name: Name, meta: Meta)
+
+}
+
+/**
+ * Define meta in this [DataSet]
+ */
+public fun <T : Any> DataSetBuilder<T>.meta(value: Meta): Unit = meta(Name.EMPTY, value)
+
+/**
+ * Define meta in this [DataSet]
+ */
+public fun <T : Any> DataSetBuilder<T>.meta(mutableMeta: MutableMeta.() -> Unit): Unit = meta(Meta(mutableMeta))
+
+@PublishedApi
+internal class SubSetBuilder<in T : Any>(
+    private val parent: DataSetBuilder<T>,
+    private val branch: Name,
+) : DataSetBuilder<T> {
+    override val dataType: KType get() = parent.dataType
+
+    override fun remove(name: Name) {
+        parent.remove(branch + name)
+    }
+
+    override fun data(name: Name, data: Data<T>?) {
+        parent.data(branch + name, data)
+    }
+
+    override fun node(name: Name, dataSet: DataSet<T>) {
+        parent.node(branch + name, dataSet)
+    }
+
+    override fun meta(name: Name, meta: Meta) {
+        parent.meta(branch + name, meta)
+    }
+}
+
+public inline fun <T : Any> DataSetBuilder<T>.node(
+    name: Name,
+    crossinline block: DataSetBuilder<T>.() -> Unit,
+) {
+    if (name.isEmpty()) block() else SubSetBuilder(this, name).block()
+}
+
+
+public fun <T : Any> DataSetBuilder<T>.data(name: String, value: Data<T>) {
+    data(Name.parse(name), value)
+}
+
+public fun <T : Any> DataSetBuilder<T>.node(name: String, set: DataSet<T>) {
+    node(Name.parse(name), set)
+}
+
+public inline fun <T : Any> DataSetBuilder<T>.node(
+    name: String,
+    crossinline block: DataSetBuilder<T>.() -> Unit,
+): Unit = node(Name.parse(name), block)
+
+public fun <T : Any> DataSetBuilder<T>.set(value: NamedData<T>) {
+    data(value.name, value.data)
+}
+
+/**
+ * Produce lazy [Data] and emit it into the [DataSetBuilder]
+ */
+public inline fun <reified T : Any> DataSetBuilder<T>.produce(
+    name: String,
+    meta: Meta = Meta.EMPTY,
+    noinline producer: suspend () -> T,
+) {
+    val data = Data(meta, block = producer)
+    data(name, data)
+}
+
+public inline fun <reified T : Any> DataSetBuilder<T>.produce(
+    name: Name,
+    meta: Meta = Meta.EMPTY,
+    noinline producer: suspend () -> T,
+) {
+    val data = Data(meta, block = producer)
+    data(name, data)
+}
+
+/**
+ * Emit a static data with the fixed value
+ */
+public inline fun <reified T : Any> DataSetBuilder<T>.static(
+    name: String,
+    data: T,
+    meta: Meta = Meta.EMPTY,
+): Unit = data(name, Data.static(data, meta))
+
+public inline fun <reified T : Any> DataSetBuilder<T>.static(
+    name: Name,
+    data: T,
+    meta: Meta = Meta.EMPTY,
+): Unit = data(name, Data.static(data, meta))
+
+public inline fun <reified T : Any> DataSetBuilder<T>.static(
+    name: String,
+    data: T,
+    mutableMeta: MutableMeta.() -> Unit,
+): Unit = data(Name.parse(name), Data.static(data, Meta(mutableMeta)))
+
+/**
+ * Update data with given node data and meta with node meta.
+ */
+@DFExperimental
+public fun <T : Any> DataSetBuilder<T>.populateFrom(tree: DataSet<T>): Unit {
+    tree.forEach {
+        //TODO check if the place is occupied
+        data(it.name, it.data)
+    }
+}
+
+//public fun <T : Any> DataSetBuilder<T>.populateFrom(flow: Flow<NamedData<T>>) {
+//    flow.collect {
+//        data(it.name, it.data)
+//    }
+//}
+
+public fun <T : Any> DataSetBuilder<T>.populateFrom(sequence: Sequence<NamedData<T>>) {
+    sequence.forEach {
+        data(it.name, it.data)
+    }
+}

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataSource.kt

@@ -1,330 +0,0 @@
-package space.kscience.dataforge.data
-
-import kotlinx.coroutines.*
-import kotlinx.coroutines.flow.*
-import space.kscience.dataforge.meta.Meta
-import space.kscience.dataforge.misc.DFInternal
-import space.kscience.dataforge.names.*
-import kotlin.contracts.contract
-import kotlin.reflect.KType
-import kotlin.reflect.typeOf
-
-/**
- * A generic data provider
- */
-public interface DataSource<out T> {
-
-    /**
-     * The minimal common ancestor to all data in the node
-     */
-    public val dataType: KType
-
-    /**
-     * Get data with given name. Or null if it is not present
-     */
-    public fun read(name: Name): Data<T>?
-}
-
-/**
- * A data provider with possible dynamic updates
- */
-public interface ObservableDataSource<out T> : DataSource<T> {
-
-    /**
-     * Flow updates made to the data
-     */
-    public fun updates(): Flow<NamedData<T>>
-}
-
-/**
- * A tree like structure for data holding
- */
-public interface GenericDataTree<out T, out TR : GenericDataTree<T, TR>> : DataSource<T> {
-    public val self: TR
-
-    public val data: Data<T>?
-    public val items: Map<NameToken, TR>
-
-
-    override fun read(name: Name): Data<T>? = when (name.length) {
-        0 -> data
-        else -> items[name.first()]?.read(name.cutFirst())
-    }
-
-    public companion object {
-        private object EmptyDataTree : GenericDataTree<Nothing, EmptyDataTree> {
-            override val self: EmptyDataTree get() = this
-            override val data: Data<Nothing>? = null
-            override val items: Map<NameToken, EmptyDataTree> = emptyMap()
-            override val dataType: KType = typeOf<Unit>()
-
-            override fun read(name: Name): Data<Nothing>? = null
-
-        }
-
-        public val EMPTY: GenericDataTree<Nothing, *> = EmptyDataTree
-    }
-}
-
-public typealias DataTree<T> = GenericDataTree<T, GenericDataTree<T, *>>
-
-/**
- * Return a single data in this tree. Throw error if it is not single.
- */
-public fun <T> DataTree<T>.single(): NamedData<T> = asSequence().single()
-
-/**
- * An alias for easier access to tree values
- */
-public operator fun <T> DataTree<T>.get(name: Name): Data<T>? = read(name)
-
-public operator fun <T> DataTree<T>.get(name: String): Data<T>? = read(name.parseAsName())
-
-/**
- * Return a sequence of all data items in this tree.
- * This method does not take updates into account.
- */
-public fun <T> DataTree<T>.asSequence(
-    namePrefix: Name = Name.EMPTY,
-): Sequence<NamedData<T>> = sequence {
-    data?.let { yield(it.named(namePrefix)) }
-    items.forEach { (token, tree) ->
-        yieldAll(tree.asSequence(namePrefix + token))
-    }
-}
-
-public val DataTree<*>.meta: Meta? get() = data?.meta
-
-/**
- * Provide subtree if it exists
- */
-public tailrec fun <T, TR : GenericDataTree<T, TR>> GenericDataTree<T, TR>.branch(name: Name): TR? =
-    when (name.length) {
-        0 -> self
-        1 -> items[name.first()]
-        else -> items[name.first()]?.branch(name.cutFirst())
-    }
-
-public fun <T, TR : GenericDataTree<T, TR>> GenericDataTree<T, TR>.branch(name: String): TR? =
-    branch(name.parseAsName())
-
-public fun GenericDataTree<*, *>.isEmpty(): Boolean = data == null && items.isEmpty()
-
-@PublishedApi
-internal class FlatDataTree<T>(
-    override val dataType: KType,
-    private val dataSet: Map<Name, Data<T>>,
-    private val prefix: Name,
-) : GenericDataTree<T, FlatDataTree<T>> {
-    override val self: FlatDataTree<T> get() = this
-    override val data: Data<T>? get() = dataSet[prefix]
-    override val items: Map<NameToken, FlatDataTree<T>>
-        get() = dataSet.keys
-            .filter { it.startsWith(prefix) && it.length > prefix.length }
-            .map { it.tokens[prefix.length] }
-            .associateWith { FlatDataTree(dataType, dataSet, prefix + it) }
-
-    override fun read(name: Name): Data<T>? = dataSet[prefix + name]
-}
-
-/**
- * Represent this flat data map as a [DataTree] without copying it
- */
-public inline fun <reified T> Map<Name, Data<T>>.asTree(): DataTree<T> = FlatDataTree(typeOf<T>(), this, Name.EMPTY)
-
-internal fun <T> Sequence<NamedData<T>>.toTree(type: KType): DataTree<T> =
-    FlatDataTree(type, associate { it.name to it.data }, Name.EMPTY)
-
-/**
- * Collect a sequence of [NamedData] to a [DataTree]
- */
-public inline fun <reified T> Sequence<NamedData<T>>.toTree(): DataTree<T> =
-    FlatDataTree(typeOf<T>(), associate { it.name to it.data }, Name.EMPTY)
-
-public interface GenericObservableDataTree<out T, out TR : GenericObservableDataTree<T, TR>> :
-    GenericDataTree<T, TR>, ObservableDataSource<T>, AutoCloseable {
-
-    /**
-     * A scope that is used to propagate updates. When this scope is closed, no new updates could arrive.
-     */
-    public val updatesScope: CoroutineScope
-
-    /**
-     * Close this data tree updates channel
-     */
-    override fun close() {
-        updatesScope.cancel()
-    }
-
-}
-
-public typealias ObservableDataTree<T> = GenericObservableDataTree<T, GenericObservableDataTree<T, *>>
-
-/**
- * Check if the [DataTree] is observable
- */
-public fun <T> DataTree<T>.isObservable(): Boolean {
-    contract {
-        returns(true) implies (this@isObservable is GenericObservableDataTree<T, *>)
-    }
-    return this is GenericObservableDataTree<T, *>
-}
-
-/**
- * Wait for this data tree to stop spawning updates (updatesScope is closed).
- * If this [DataTree] is not observable, return immediately.
- */
-public suspend fun <T> DataTree<T>.awaitClose() {
-    if (isObservable()) {
-        updatesScope.coroutineContext[Job]?.join()
-    }
-}
-
-public fun <T> DataTree<T>.updates(): Flow<NamedData<T>> =
-    if (this is GenericObservableDataTree<T, *>) updates() else emptyFlow()
-
-public fun interface DataSink<in T> {
-    public fun put(name: Name, data: Data<T>?)
-}
-
-@DFInternal
-public class DataTreeBuilder<T>(private val type: KType) : DataSink<T> {
-    private val map = HashMap<Name, Data<T>>()
-    override fun put(name: Name, data: Data<T>?) {
-        if (data == null) {
-            map.remove(name)
-        } else {
-            map[name] = data
-        }
-    }
-
-    public fun build(): DataTree<T> = FlatDataTree(type, map, Name.EMPTY)
-}
-
-@DFInternal
-public inline fun <T> DataTree(
-    dataType: KType,
-    generator: DataSink<T>.() -> Unit,
-): DataTree<T> = DataTreeBuilder<T>(dataType).apply(generator).build()
-
-/**
- * Create and a data tree.
- */
-@OptIn(DFInternal::class)
-public inline fun <reified T> DataTree(
-    generator: DataSink<T>.() -> Unit,
-): DataTree<T> = DataTreeBuilder<T>(typeOf<T>()).apply(generator).build()
-
-/**
- * A mutable version of [GenericDataTree]
- */
-public interface MutableDataTree<T> : GenericObservableDataTree<T, MutableDataTree<T>>, DataSink<T> {
-    override var data: Data<T>?
-
-    override val items: Map<NameToken, MutableDataTree<T>>
-
-    public fun getOrCreateItem(token: NameToken): MutableDataTree<T>
-
-    public operator fun set(token: NameToken, data: Data<T>?)
-
-    override fun put(name: Name, data: Data<T>?): Unit = set(name, data)
-}
-
-public tailrec operator fun <T> MutableDataTree<T>.set(name: Name, data: Data<T>?): Unit {
-    when (name.length) {
-        0 -> this.data = data
-        1 -> set(name.first(), data)
-        else -> getOrCreateItem(name.first())[name.cutFirst()] = data
-    }
-}
-
-private class MutableDataTreeImpl<T>(
-    override val dataType: KType,
-    override val updatesScope: CoroutineScope,
-) : MutableDataTree<T> {
-
-
-    private val updates = MutableSharedFlow<NamedData<T>>()
-
-    private val children = HashMap<NameToken, MutableDataTree<T>>()
-
-    override var data: Data<T>? = null
-        set(value) {
-            if (!updatesScope.isActive) error("Can't send updates to closed MutableDataTree")
-            field = value
-            if (value != null) {
-                updatesScope.launch {
-                    updates.emit(value.named(Name.EMPTY))
-                }
-            }
-        }
-
-    override val items: Map<NameToken, MutableDataTree<T>> get() = children
-
-    override fun getOrCreateItem(token: NameToken): MutableDataTree<T> = children.getOrPut(token){
-        MutableDataTreeImpl(dataType, updatesScope)
-    }
-
-    override val self: MutableDataTree<T> get() = this
-
-    override fun set(token: NameToken, data: Data<T>?) {
-        if (!updatesScope.isActive) error("Can't send updates to closed MutableDataTree")
-        val subTree = getOrCreateItem(token)
-        subTree.updates().onEach {
-            updates.emit(it.named(token + it.name))
-        }.launchIn(updatesScope)
-        subTree.data = data
-    }
-
-    override fun updates(): Flow<NamedData<T>> = updates
-}
-
-/**
- * Create a new [MutableDataTree]
- *
- * @param parentScope a [CoroutineScope] to control data propagation. By default uses [GlobalScope]
- */
-@OptIn(DelicateCoroutinesApi::class)
-public fun <T> MutableDataTree(
-    type: KType,
-    parentScope: CoroutineScope = GlobalScope,
-): MutableDataTree<T> = MutableDataTreeImpl<T>(
-    type,
-    CoroutineScope(parentScope.coroutineContext + Job(parentScope.coroutineContext[Job]))
-)
-
-/**
- * Create and initialize a observable mutable data tree.
- */
-@OptIn(DelicateCoroutinesApi::class)
-public inline fun <reified T> MutableDataTree(
-    parentScope: CoroutineScope = GlobalScope,
-    generator: MutableDataTree<T>.() -> Unit = {},
-): MutableDataTree<T> = MutableDataTree<T>(typeOf<T>(), parentScope).apply { generator() }
-
-//@DFInternal
-//public fun <T> ObservableDataTree(
-//    type: KType,
-//    scope: CoroutineScope,
-//    generator: suspend MutableDataTree<T>.() -> Unit = {},
-//): ObservableDataTree<T> = MutableDataTree<T>(type, scope.coroutineContext).apply(generator)
-
-public inline fun <reified T> ObservableDataTree(
-    parentScope: CoroutineScope,
-    generator: MutableDataTree<T>.() -> Unit = {},
-): ObservableDataTree<T> = MutableDataTree<T>(typeOf<T>(), parentScope).apply(generator)
-
-
-/**
- * Collect a [Sequence] into an observable tree with additional [updates]
- */
-public fun <T> Sequence<NamedData<T>>.toObservableTree(
-    dataType: KType,
-    parentScope: CoroutineScope,
-    updates: Flow<NamedData<T>>,
-): ObservableDataTree<T> = MutableDataTree<T>(dataType, parentScope).apply {
-    this.putAll(this@toObservableTree)
-    updates.onEach {
-        put(it.name, it.data)
-    }.launchIn(updatesScope)
-}

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataTree.kt

@@ -0,0 +1,119 @@
+package space.kscience.dataforge.data
+
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.misc.DFInternal
+import space.kscience.dataforge.misc.DfType
+import space.kscience.dataforge.names.*
+import kotlin.collections.component1
+import kotlin.collections.component2
+import kotlin.reflect.KType
+import kotlin.reflect.typeOf
+
+public sealed class DataTreeItem<out T : Any> {
+
+    public abstract val meta: Meta
+
+    public class Node<out T : Any>(public val tree: DataTree<T>) : DataTreeItem<T>() {
+        override val meta: Meta get() = tree.meta
+    }
+
+    public class Leaf<out T : Any>(public val data: Data<T>) : DataTreeItem<T>() {
+        override val meta: Meta get() = data.meta
+    }
+}
+
+public val <T : Any> DataTreeItem<T>.type: KType
+    get() = when (this) {
+        is DataTreeItem.Node -> tree.dataType
+        is DataTreeItem.Leaf -> data.type
+    }
+
+/**
+ * A tree-like [DataSet] grouped into the node. All data inside the node must inherit its type
+ */
+@DfType(DataTree.TYPE)
+public interface DataTree<out T : Any> : DataSet<T> {
+
+    /**
+     * Top-level children items of this [DataTree]
+     */
+    public val items: Map<NameToken, DataTreeItem<T>>
+
+    override val meta: Meta get() = items[META_ITEM_NAME_TOKEN]?.meta ?: Meta.EMPTY
+
+    override fun iterator(): Iterator<NamedData<T>> = iterator {
+        items.forEach { (token, childItem: DataTreeItem<T>) ->
+            if (!token.body.startsWith("@")) {
+                when (childItem) {
+                    is DataTreeItem.Leaf -> yield(childItem.data.named(token.asName()))
+                    is DataTreeItem.Node -> yieldAll(childItem.tree.asSequence().map { it.named(token + it.name) })
+                }
+            }
+        }
+    }
+
+    override fun get(name: Name): Data<T>? = when (name.length) {
+        0 -> null
+        1 -> items[name.firstOrNull()!!].data
+        else -> items[name.firstOrNull()!!].tree?.get(name.cutFirst())
+    }
+
+    public companion object {
+        public const val TYPE: String = "dataTree"
+
+        /**
+         * A name token used to designate tree node meta
+         */
+        public val META_ITEM_NAME_TOKEN: NameToken = NameToken("@meta")
+
+        @DFInternal
+        public fun <T : Any> emptyWithType(type: KType, meta: Meta = Meta.EMPTY): DataTree<T> = object : DataTree<T> {
+            override val items: Map<NameToken, DataTreeItem<T>> get() = emptyMap()
+            override val dataType: KType get() = type
+            override val meta: Meta get() = meta
+        }
+
+        @OptIn(DFInternal::class)
+        public inline fun <reified T : Any> empty(meta: Meta = Meta.EMPTY): DataTree<T> =
+            emptyWithType<T>(typeOf<T>(), meta)
+    }
+}
+
+public fun <T : Any> DataTree<T>.listChildren(prefix: Name): List<Name> =
+    getItem(prefix).tree?.items?.keys?.map { prefix + it } ?: emptyList()
+
+/**
+ * Get a [DataTreeItem] with given [name] or null if the item does not exist
+ */
+public tailrec fun <T : Any> DataTree<T>.getItem(name: Name): DataTreeItem<T>? = when (name.length) {
+    0 -> DataTreeItem.Node(this)
+    1 -> items[name.firstOrNull()]
+    else -> items[name.firstOrNull()!!].tree?.getItem(name.cutFirst())
+}
+
+public val <T : Any> DataTreeItem<T>?.tree: DataTree<T>? get() = (this as? DataTreeItem.Node<T>)?.tree
+public val <T : Any> DataTreeItem<T>?.data: Data<T>? get() = (this as? DataTreeItem.Leaf<T>)?.data
+
+/**
+ * A [Sequence] of all children including nodes
+ */
+public fun <T : Any> DataTree<T>.traverseItems(): Sequence<Pair<Name, DataTreeItem<T>>> = sequence {
+    items.forEach { (head, item) ->
+        yield(head.asName() to item)
+        if (item is DataTreeItem.Node) {
+            val subSequence = item.tree.traverseItems()
+                .map { (name, data) -> (head.asName() + name) to data }
+            yieldAll(subSequence)
+        }
+    }
+}
+
+/**
+ * Get a branch of this [DataTree] with a given [branchName].
+ * The difference from similar method for [DataSet] is that internal logic is more simple and the return value is a [DataTree]
+ */
+@OptIn(DFInternal::class)
+public fun <T : Any> DataTree<T>.branch(branchName: Name): DataTree<T> =
+    getItem(branchName)?.tree ?: DataTree.emptyWithType(dataType)
+
+public fun <T : Any> DataTree<T>.branch(branchName: String): DataTree<T> = branch(branchName.parseAsName())

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataTreeBuilder.kt

@@ -0,0 +1,121 @@
+package space.kscience.dataforge.data
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.launch
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.misc.DFInternal
+import space.kscience.dataforge.misc.ThreadSafe
+import space.kscience.dataforge.names.*
+import kotlin.collections.set
+import kotlin.coroutines.CoroutineContext
+import kotlin.reflect.KType
+import kotlin.reflect.typeOf
+
+public interface DataSourceBuilder<T : Any> : DataSetBuilder<T>, DataSource<T> {
+    override val updates: MutableSharedFlow<Name>
+}
+
+/**
+ * A mutable [DataTree] that propagates updates
+ */
+public class DataTreeBuilder<T : Any> internal constructor(
+    override val dataType: KType,
+    coroutineContext: CoroutineContext,
+) : DataTree<T>, DataSourceBuilder<T> {
+
+    override val coroutineContext: CoroutineContext =
+        coroutineContext + Job(coroutineContext[Job]) + GoalExecutionRestriction()
+
+    private val treeItems = HashMap<NameToken, DataTreeItem<T>>()
+
+    override val items: Map<NameToken, DataTreeItem<T>>
+        get() = treeItems.filter { !it.key.body.startsWith("@") }
+
+    override val updates: MutableSharedFlow<Name> = MutableSharedFlow<Name>()
+
+    @ThreadSafe
+    private fun remove(token: NameToken) {
+        if (treeItems.remove(token) != null) {
+            launch {
+                updates.emit(token.asName())
+            }
+        }
+    }
+
+    override fun remove(name: Name) {
+        if (name.isEmpty()) error("Can't remove the root node")
+        (getItem(name.cutLast()).tree as? DataTreeBuilder)?.remove(name.lastOrNull()!!)
+    }
+
+    @ThreadSafe
+    private fun set(token: NameToken, data: Data<T>) {
+        treeItems[token] = DataTreeItem.Leaf(data)
+    }
+
+    @ThreadSafe
+    private fun set(token: NameToken, node: DataTree<T>) {
+        treeItems[token] = DataTreeItem.Node(node)
+    }
+
+    private fun getOrCreateNode(token: NameToken): DataTreeBuilder<T> =
+        (treeItems[token] as? DataTreeItem.Node<T>)?.tree as? DataTreeBuilder<T>
+            ?: DataTreeBuilder<T>(dataType, coroutineContext).also { set(token, it) }
+
+    private fun getOrCreateNode(name: Name): DataTreeBuilder<T> = when (name.length) {
+        0 -> this
+        1 -> getOrCreateNode(name.firstOrNull()!!)
+        else -> getOrCreateNode(name.firstOrNull()!!).getOrCreateNode(name.cutFirst())
+    }
+
+    override fun data(name: Name, data: Data<T>?) {
+        if (data == null) {
+            remove(name)
+        } else {
+            when (name.length) {
+                0 -> error("Can't add data with empty name")
+                1 -> set(name.firstOrNull()!!, data)
+                2 -> getOrCreateNode(name.cutLast()).set(name.lastOrNull()!!, data)
+            }
+        }
+        launch {
+            updates.emit(name)
+        }
+    }
+
+    override fun meta(name: Name, meta: Meta) {
+        val item = getItem(name)
+        if (item is DataTreeItem.Leaf) error("TODO: Can't change meta of existing leaf item.")
+        data(name + DataTree.META_ITEM_NAME_TOKEN, Data.empty(meta))
+    }
+}
+
+/**
+ * Create a dynamic [DataSource]. Initial data is placed synchronously.
+ */
+@DFInternal
+@Suppress("FunctionName")
+public fun <T : Any> DataSource(
+    type: KType,
+    parent: CoroutineScope,
+    block: DataSourceBuilder<T>.() -> Unit = {},
+): DataTreeBuilder<T> = DataTreeBuilder<T>(type, parent.coroutineContext).apply(block)
+
+@Suppress("OPT_IN_USAGE", "FunctionName")
+public inline fun <reified T : Any> DataSource(
+    parent: CoroutineScope,
+    crossinline block: DataSourceBuilder<T>.() -> Unit = {},
+): DataTreeBuilder<T> = DataSource(typeOf<T>(), parent) { block() }
+
+public inline fun <reified T : Any> DataSourceBuilder<T>.emit(
+    name: Name,
+    parent: CoroutineScope,
+    noinline block: DataSourceBuilder<T>.() -> Unit,
+): Unit = node(name, DataSource(parent, block))
+
+public inline fun <reified T : Any> DataSourceBuilder<T>.emit(
+    name: String,
+    parent: CoroutineScope,
+    noinline block: DataSourceBuilder<T>.() -> Unit,
+): Unit = node(Name.parse(name), DataSource(parent, block))

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/Goal.kt

@@ -9,7 +9,7 @@ import kotlin.coroutines.EmptyCoroutineContext
  * Lazy computation result with its dependencies to allowing to stat computing dependencies ahead of time
  */
 public interface Goal<out T> {
-    public val dependencies: Iterable<Goal<*>>
+    public val dependencies: Collection<Goal<*>>
 
     /**
      * Returns current running coroutine if the goal is started. Null if the computation is not started.
@@ -54,7 +54,7 @@ public open class StaticGoal<T>(public val value: T) : Goal<T> {
  */
 public open class LazyGoal<T>(
     private val coroutineContext: CoroutineContext = EmptyCoroutineContext,
-    override val dependencies: Iterable<Goal<*>> = emptyList(),
+    override val dependencies: Collection<Goal<*>> = emptyList(),
     public val block: suspend () -> T,
 ) : Goal<T> {
 
@@ -82,8 +82,8 @@ public open class LazyGoal<T>(
         }
 
         log?.emit { "Starting dependencies computation for ${this@LazyGoal}" }
-        val startedDependencies = dependencies.map { goal ->
-            goal.async(coroutineScope)
+        val startedDependencies = this.dependencies.map { goal ->
+            goal.run { async(coroutineScope) }
         }
         return deferred ?: coroutineScope.async(
             coroutineContext

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/GroupRule.kt

@@ -15,12 +15,13 @@
  */
 package space.kscience.dataforge.data
 
+import kotlinx.coroutines.launch
 import space.kscience.dataforge.meta.get
 import space.kscience.dataforge.meta.string
 import space.kscience.dataforge.misc.DFInternal
 
 public interface GroupRule {
-    public fun <T : Any> gather(set: DataTree<T>): Map<String, DataTree<T>>
+    public fun <T : Any> gather(set: DataSet<T>): Map<String, DataSet<T>>
 
     public companion object {
         /**
@@ -38,17 +39,39 @@ public interface GroupRule {
         ): GroupRule = object : GroupRule {
 
             override fun <T : Any> gather(
-                set: DataTree<T>,
-            ): Map<String, DataTree<T>> {
-                val map = HashMap<String, DataTreeBuilder<T>>()
+                set: DataSet<T>,
+            ): Map<String, DataSet<T>> {
+                val map = HashMap<String, DataSet<T>>()
 
-                set.forEach { data ->
-                    val tagValue: String = data.meta[key]?.string ?: defaultTagValue
-                    map.getOrPut(tagValue) { DataTreeBuilder(set.dataType) }.put(data.name, data.data)
+                if (set is DataSource) {
+                    set.forEach { data ->
+                        val tagValue: String = data.meta[key]?.string ?: defaultTagValue
+                        (map.getOrPut(tagValue) { DataTreeBuilder(set.dataType, set.coroutineContext) } as DataTreeBuilder<T>)
+                            .data(data.name, data.data)
+
+                        set.launch {
+                            set.updates.collect { name ->
+                                val dataUpdate = set[name]
+
+                                val updateTagValue = dataUpdate?.meta?.get(key)?.string ?: defaultTagValue
+                                map.getOrPut(updateTagValue) {
+                                    DataSource(set.dataType, this) {
+                                        data(name, dataUpdate)
+                                    }
+                                }
+                            }
+                        }
+                    }
+                } else {
+                    set.forEach { data ->
+                        val tagValue: String = data.meta[key]?.string ?: defaultTagValue
+                        (map.getOrPut(tagValue) { StaticDataTree(set.dataType) } as StaticDataTree<T>)
+                            .data(data.name, data.data)
+                    }
                 }
 
 
-                return map.mapValues { it.value.build() }
+                return map
             }
         }
     }

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/NamedData.kt

@@ -4,7 +4,7 @@ import space.kscience.dataforge.meta.isEmpty
 import space.kscience.dataforge.misc.Named
 import space.kscience.dataforge.names.Name
 
-public interface NamedData<out T> : Named, Data<T> {
+public interface NamedData<out T : Any> : Named, Data<T> {
     override val name: Name
     public val data: Data<T>
 }
@@ -12,7 +12,7 @@ public interface NamedData<out T> : Named, Data<T> {
 public operator fun NamedData<*>.component1(): Name = name
 public operator fun <T: Any> NamedData<T>.component2(): Data<T> = data
 
-private class NamedDataImpl<T>(
+private class NamedDataImpl<out T : Any>(
     override val name: Name,
     override val data: Data<T>,
 ) : Data<T> by data, NamedData<T> {
@@ -28,7 +28,7 @@ private class NamedDataImpl<T>(
     }
 }
 
-public fun <T> Data<T>.named(name: Name): NamedData<T> = if (this is NamedData) {
+public fun <T : Any> Data<T>.named(name: Name): NamedData<T> = if (this is NamedData) {
     NamedDataImpl(name, this.data)
 } else {
     NamedDataImpl(name, this)

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/StaticDataTree.kt

@@ -0,0 +1,80 @@
+package space.kscience.dataforge.data
+
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.misc.DFExperimental
+import space.kscience.dataforge.names.*
+import kotlin.reflect.KType
+import kotlin.reflect.typeOf
+
+@PublishedApi
+internal class StaticDataTree<T : Any>(
+    override val dataType: KType,
+) : DataSetBuilder<T>, DataTree<T> {
+
+    private val _items: MutableMap<NameToken, DataTreeItem<T>> = HashMap()
+
+    override val items: Map<NameToken, DataTreeItem<T>>
+        get() = _items.filter { !it.key.body.startsWith("@") }
+
+    override fun remove(name: Name) {
+        when (name.length) {
+            0 -> error("Can't remove root tree node")
+            1 -> _items.remove(name.firstOrNull()!!)
+            else -> (_items[name.firstOrNull()!!].tree as? StaticDataTree<T>)?.remove(name.cutFirst())
+        }
+    }
+
+    private fun getOrCreateNode(name: Name): StaticDataTree<T> = when (name.length) {
+        0 -> this
+        1 -> {
+            val itemName = name.firstOrNull()!!
+            (_items[itemName].tree as? StaticDataTree<T>) ?: StaticDataTree<T>(dataType).also {
+                _items[itemName] = DataTreeItem.Node(it)
+            }
+        }
+        else -> getOrCreateNode(name.cutLast()).getOrCreateNode(name.lastOrNull()!!.asName())
+    }
+
+    private fun set(name: Name, item: DataTreeItem<T>?) {
+        if (name.isEmpty()) error("Can't set top level tree node")
+        if (item == null) {
+            remove(name)
+        } else {
+            getOrCreateNode(name.cutLast())._items[name.lastOrNull()!!] = item
+        }
+    }
+
+    override fun data(name: Name, data: Data<T>?) {
+        set(name, data?.let { DataTreeItem.Leaf(it) })
+    }
+
+    override fun node(name: Name, dataSet: DataSet<T>) {
+        if (dataSet is StaticDataTree) {
+            set(name, DataTreeItem.Node(dataSet))
+        } else {
+            dataSet.forEach {
+                data(name + it.name, it.data)
+            }
+        }
+    }
+
+    override fun meta(name: Name, meta: Meta) {
+        val item = getItem(name)
+        if (item is DataTreeItem.Leaf) TODO("Can't change meta of existing leaf item.")
+        data(name + DataTree.META_ITEM_NAME_TOKEN, Data.empty(meta))
+    }
+}
+
+public inline fun <T : Any> DataTree(
+    dataType: KType,
+    block: DataSetBuilder<T>.() -> Unit,
+): DataTree<T> = StaticDataTree<T>(dataType).apply { block() }
+
+public inline fun <reified T : Any> DataTree(
+    noinline block: DataSetBuilder<T>.() -> Unit,
+): DataTree<T> = DataTree(typeOf<T>(), block)
+
+@OptIn(DFExperimental::class)
+public fun <T : Any> DataSet<T>.seal(): DataTree<T> = DataTree(dataType) {
+    populateFrom(this@seal)
+}

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/dataBuilders.kt

@@ -1,132 +0,0 @@
-package space.kscience.dataforge.data
-
-import kotlinx.coroutines.Job
-import kotlinx.coroutines.flow.launchIn
-import kotlinx.coroutines.flow.onEach
-import space.kscience.dataforge.meta.Meta
-import space.kscience.dataforge.meta.MutableMeta
-import space.kscience.dataforge.misc.DFExperimental
-import space.kscience.dataforge.names.Name
-import space.kscience.dataforge.names.asName
-import space.kscience.dataforge.names.isEmpty
-import space.kscience.dataforge.names.plus
-
-
-public fun <T> DataSink<T>.put(value: NamedData<T>) {
-    put(value.name, value.data)
-}
-
-public fun <T> DataSink<T>.branch(dataTree: DataTree<T>) {
-    putAll(dataTree.asSequence())
-}
-
-public inline fun <T> DataSink<T>.branch(
-    prefix: Name,
-    block: DataSink<T>.() -> Unit,
-) {
-    if (prefix.isEmpty()) {
-        apply(block)
-    } else {
-        val proxyDataSink = DataSink { nameWithoutPrefix, data ->
-            this.put(prefix + nameWithoutPrefix, data)
-        }
-
-        proxyDataSink.apply(block)
-    }
-}
-
-public inline fun <T> DataSink<T>.branch(
-    prefix: String,
-    block: DataSink<T>.() -> Unit,
-): Unit = branch(prefix.asName(), block)
-
-
-public fun <T> DataSink<T>.put(name: String, value: Data<T>) {
-    put(Name.parse(name), value)
-}
-
-public fun <T> DataSink<T>.branch(name: Name, set: DataTree<T>) {
-    branch(name) { putAll(set.asSequence()) }
-}
-
-public fun <T> DataSink<T>.branch(name: String, set: DataTree<T>) {
-    branch(Name.parse(name)) { putAll(set.asSequence()) }
-}
-
-/**
- * Produce lazy [Data] and emit it into the [MutableDataTree]
- */
-public inline fun <reified T> DataSink<T>.put(
-    name: String,
-    meta: Meta = Meta.EMPTY,
-    noinline producer: suspend () -> T,
-) {
-    val data = Data(meta, block = producer)
-    put(name, data)
-}
-
-public inline fun <reified T> DataSink<T>.put(
-    name: Name,
-    meta: Meta = Meta.EMPTY,
-    noinline producer: suspend () -> T,
-) {
-    val data = Data(meta, block = producer)
-    put(name, data)
-}
-
-/**
- * Emit static data with the fixed value
- */
-public inline fun <reified T> DataSink<T>.wrap(
-    name: String,
-    data: T,
-    meta: Meta = Meta.EMPTY,
-): Unit = put(name, Data.static(data, meta))
-
-public inline fun <reified T> DataSink<T>.wrap(
-    name: Name,
-    data: T,
-    meta: Meta = Meta.EMPTY,
-): Unit = put(name, Data.static(data, meta))
-
-public inline fun <reified T> DataSink<T>.wrap(
-    name: String,
-    data: T,
-    mutableMeta: MutableMeta.() -> Unit,
-): Unit = put(Name.parse(name), Data.static(data, Meta(mutableMeta)))
-
-
-public fun <T> DataSink<T>.putAll(sequence: Sequence<NamedData<T>>) {
-    sequence.forEach {
-        put(it.name, it.data)
-    }
-}
-
-public fun <T> DataSink<T>.putAll(tree: DataTree<T>) {
-    this.putAll(tree.asSequence())
-}
-
-
-/**
- * Update data with given node data and meta with node meta.
- */
-@DFExperimental
-public fun <T> MutableDataTree<T>.putAll(source: DataTree<T>) {
-    source.forEach {
-        put(it.name, it.data)
-    }
-}
-
-/**
- * Copy given data set and mirror its changes to this [DataSink] in [this@setAndObserve]. Returns an update [Job]
- */
-public fun <T : Any> DataSink<T>.watchBranch(
-    name: Name,
-    dataSet: ObservableDataTree<T>,
-): Job {
-    branch(name, dataSet)
-    return dataSet.updates().onEach {
-        put(name + it.name, it.data)
-    }.launchIn(dataSet.updatesScope)
-
-}

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/dataFilter.kt

@@ -0,0 +1,105 @@
+package space.kscience.dataforge.data
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.filter
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.mapNotNull
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.misc.DFExperimental
+import space.kscience.dataforge.names.*
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+import kotlin.reflect.KType
+
+
+/**
+ * A stateless filtered [DataSet]
+ */
+public fun <T : Any> DataSet<T>.filter(
+    predicate: (Name, Meta) -> Boolean,
+): DataSource<T> = object : DataSource<T> {
+
+    override val dataType: KType get() = this@filter.dataType
+
+    override val coroutineContext: CoroutineContext
+        get() = (this@filter as? DataSource)?.coroutineContext ?: EmptyCoroutineContext
+
+
+    override val meta: Meta get() = this@filter.meta
+
+    override fun iterator(): Iterator<NamedData<T>> = iterator {
+        for (d in this@filter) {
+            if (predicate(d.name, d.meta)) {
+                yield(d)
+            }
+        }
+    }
+
+    override fun get(name: Name): Data<T>? = this@filter.get(name)?.takeIf {
+        predicate(name, it.meta)
+    }
+
+    override val updates: Flow<Name> = this@filter.updates.filter flowFilter@{ name ->
+        val theData = this@filter[name] ?: return@flowFilter false
+        predicate(name, theData.meta)
+    }
+}
+
+/**
+ * Generate a wrapper data set with a given name prefix appended to all names
+ */
+public fun <T : Any> DataSet<T>.withNamePrefix(prefix: Name): DataSet<T> = if (prefix.isEmpty()) {
+    this
+} else object : DataSource<T> {
+
+    override val dataType: KType get() = this@withNamePrefix.dataType
+
+    override val coroutineContext: CoroutineContext
+        get() = (this@withNamePrefix as? DataSource)?.coroutineContext ?: EmptyCoroutineContext
+
+    override val meta: Meta get() = this@withNamePrefix.meta
+
+
+    override fun iterator(): Iterator<NamedData<T>> = iterator {
+        for (d in this@withNamePrefix) {
+            yield(d.data.named(prefix + d.name))
+        }
+    }
+
+    override fun get(name: Name): Data<T>? =
+        name.removeFirstOrNull(name)?.let { this@withNamePrefix.get(it) }
+
+    override val updates: Flow<Name> get() = this@withNamePrefix.updates.map { prefix + it }
+}
+
+/**
+ * Get a subset of data starting with a given [branchName]
+ */
+public fun <T : Any> DataSet<T>.branch(branchName: Name): DataSet<T> = if (branchName.isEmpty()) {
+    this
+} else object : DataSource<T> {
+    override val dataType: KType get() = this@branch.dataType
+
+    override val coroutineContext: CoroutineContext
+        get() = (this@branch as? DataSource)?.coroutineContext ?: EmptyCoroutineContext
+
+    override val meta: Meta get() = this@branch.meta
+
+    override fun iterator(): Iterator<NamedData<T>> = iterator {
+        for (d in this@branch) {
+            d.name.removeFirstOrNull(branchName)?.let { name ->
+                yield(d.data.named(name))
+            }
+        }
+    }
+
+    override fun get(name: Name): Data<T>? = this@branch.get(branchName + name)
+
+    override val updates: Flow<Name> get() = this@branch.updates.mapNotNull { it.removeFirstOrNull(branchName) }
+}
+
+public fun <T : Any> DataSet<T>.branch(branchName: String): DataSet<T> = this@branch.branch(branchName.parseAsName())
+
+@DFExperimental
+public suspend fun <T : Any> DataSet<T>.rootData(): Data<T>? = get(Name.EMPTY)
+

dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/dataTransform.kt

@@ -9,14 +9,14 @@ import kotlin.coroutines.EmptyCoroutineContext
 import kotlin.reflect.KType
 import kotlin.reflect.typeOf
 
-public data class ValueWithMeta<T>(val value: T, val meta: Meta)
+public data class ValueWithMeta<T>(val meta: Meta, val value: T)
 
-public suspend fun <T> Data<T>.awaitWithMeta(): ValueWithMeta<T> = ValueWithMeta(await(), meta)
+public suspend fun <T : Any> Data<T>.awaitWithMeta(): ValueWithMeta<T> = ValueWithMeta(meta, await())
 
-public data class NamedValueWithMeta<T>(val name: Name, val value: T, val meta: Meta)
+public data class NamedValueWithMeta<T>(val name: Name, val meta: Meta, val value: T)
 
-public suspend fun <T> NamedData<T>.awaitWithMeta(): NamedValueWithMeta<T> =
-    NamedValueWithMeta(name, await(), meta)
+public suspend fun <T : Any> NamedData<T>.awaitWithMeta(): NamedValueWithMeta<T> =
+    NamedValueWithMeta(name, meta, await())
 
 
 /**
@@ -25,7 +25,7 @@ public suspend fun <T> NamedData<T>.awaitWithMeta(): NamedValueWithMeta<T> =
  * @param meta for the resulting data. By default equals input data.
  * @param block the transformation itself
  */
-public inline fun <T, reified R> Data<T>.transform(
+public inline fun <T : Any, reified R : Any> Data<T>.map(
     meta: Meta = this.meta,
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     crossinline block: suspend (T) -> R,
@@ -36,7 +36,7 @@ public inline fun <T, reified R> Data<T>.transform(
 /**
  * Combine this data with the other data using [block]. See [Data::map] for other details
  */
-public inline fun <T1, T2, reified R> Data<T1>.combine(
+public inline fun <T1 : Any, T2 : Any, reified R : Any> Data<T1>.combine(
     other: Data<T2>,
     meta: Meta = this.meta,
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
@@ -58,7 +58,20 @@ internal fun Iterable<Data<*>>.joinMeta(): Meta = Meta {
     }
 }
 
-
+/**
+ * Lazily reduce a collection of [Data] to a single data.
+ */
+public inline fun <T : Any, reified R : Any> Collection<Data<T>>.reduceToData(
+    meta: Meta = joinMeta(),
+    coroutineContext: CoroutineContext = EmptyCoroutineContext,
+    crossinline block: suspend (List<ValueWithMeta<T>>) -> R,
+): Data<R> = Data(
+    meta,
+    coroutineContext,
+    this
+) {
+    block(map { it.awaitWithMeta() })
+}
 
 @PublishedApi
 internal fun Map<*, Data<*>>.joinMeta(): Meta = Meta {
@@ -69,7 +82,7 @@ internal fun Map<*, Data<*>>.joinMeta(): Meta = Meta {
 }
 
 @DFInternal
-public fun <K, T, R> Map<K, Data<T>>.reduceToData(
+public fun <K, T : Any, R : Any> Map<K, Data<T>>.reduceToData(
     outputType: KType,
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
@@ -89,7 +102,7 @@ public fun <K, T, R> Map<K, Data<T>>.reduceToData(
  * @param T type of the input goal
  * @param R type of the result goal
  */
-public inline fun <K, T, reified R> Map<K, Data<T>>.reduceToData(
+public inline fun <K, T : Any, reified R : Any> Map<K, Data<T>>.reduceToData(
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     crossinline block: suspend (Map<K, ValueWithMeta<T>>) -> R,
@@ -104,7 +117,7 @@ public inline fun <K, T, reified R> Map<K, Data<T>>.reduceToData(
 //Iterable operations
 
 @DFInternal
-public inline fun <T, R> Iterable<Data<T>>.reduceToData(
+public inline fun <T : Any, R : Any> Iterable<Data<T>>.reduceToData(
     outputType: KType,
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
@@ -119,7 +132,7 @@ public inline fun <T, R> Iterable<Data<T>>.reduceToData(
 }
 
 @OptIn(DFInternal::class)
-public inline fun <T, reified R> Iterable<Data<T>>.reduceToData(
+public inline fun <T : Any, reified R : Any> Iterable<Data<T>>.reduceToData(
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     crossinline transformation: suspend (Collection<ValueWithMeta<T>>) -> R,
@@ -127,7 +140,7 @@ public inline fun <T, reified R> Iterable<Data<T>>.reduceToData(
     transformation(it)
 }
 
-public inline fun <T, reified R> Iterable<Data<T>>.foldToData(
+public inline fun <T : Any, reified R : Any> Iterable<Data<T>>.foldToData(
     initial: R,
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
@@ -142,7 +155,7 @@ public inline fun <T, reified R> Iterable<Data<T>>.foldToData(
  * Transform an [Iterable] of [NamedData] to a single [Data].
  */
 @DFInternal
-public inline fun <T, R> Iterable<NamedData<T>>.reduceNamedToData(
+public inline fun <T : Any, R : Any> Iterable<NamedData<T>>.reduceNamedToData(
     outputType: KType,
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
@@ -157,7 +170,7 @@ public inline fun <T, R> Iterable<NamedData<T>>.reduceNamedToData(
 }
 
 @OptIn(DFInternal::class)
-public inline fun <T, reified R> Iterable<NamedData<T>>.reduceNamedToData(
+public inline fun <T : Any, reified R : Any> Iterable<NamedData<T>>.reduceNamedToData(
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     crossinline transformation: suspend (Collection<NamedValueWithMeta<T>>) -> R,
@@ -168,7 +181,7 @@ public inline fun <T, reified R> Iterable<NamedData<T>>.reduceNamedToData(
 /**
  * Fold a [Iterable] of named data into a single [Data]
  */
-public inline fun <T, reified R> Iterable<NamedData<T>>.foldNamedToData(
+public inline fun <T : Any, reified R : Any> Iterable<NamedData<T>>.foldNamedToData(
     initial: R,
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
@@ -182,52 +195,53 @@ public inline fun <T, reified R> Iterable<NamedData<T>>.foldNamedToData(
 //DataSet operations
 
 @DFInternal
-public suspend fun <T, R> DataTree<T>.transform(
+public suspend fun <T : Any, R : Any> DataSet<T>.map(
     outputType: KType,
     metaTransform: MutableMeta.() -> Unit = {},
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     block: suspend (NamedValueWithMeta<T>) -> R,
-): DataTree<R> = DataTree<R>(outputType){
-    //quasi-synchronous processing of elements in the tree
-    asSequence().forEach { namedData: NamedData<T> ->
-        val newMeta = namedData.meta.toMutableMeta().apply(metaTransform).seal()
-        val d = Data(outputType, newMeta, coroutineContext, listOf(namedData)) {
-            block(namedData.awaitWithMeta())
+): DataTree<R> = DataTree<R>(outputType) {
+    forEach {
+        val newMeta = it.meta.toMutableMeta().apply(metaTransform).seal()
+        val d = Data(outputType, newMeta, coroutineContext, listOf(it)) {
+            block(it.awaitWithMeta())
         }
-        put(namedData.name, d)
+        data(it.name, d)
     }
 }
 
 @OptIn(DFInternal::class)
-public suspend inline fun <T, reified R> DataTree<T>.transform(
+public suspend inline fun <T : Any, reified R : Any> DataSet<T>.map(
     noinline metaTransform: MutableMeta.() -> Unit = {},
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     noinline block: suspend (NamedValueWithMeta<T>) -> R,
-): DataTree<R> = this@transform.transform(typeOf<R>(), metaTransform, coroutineContext, block)
+): DataTree<R> = map(typeOf<R>(), metaTransform, coroutineContext, block)
 
-public inline fun <T> DataTree<T>.forEach(block: (NamedData<T>) -> Unit) {
-    asSequence().forEach(block)
+public inline fun <T : Any> DataSet<T>.forEach(block: (NamedData<T>) -> Unit) {
+    for (d in this) {
+        block(d)
+    }
 }
 
 // DataSet reduction
 
 @PublishedApi
-internal fun DataTree<*>.joinMeta(): Meta = Meta {
-    asSequence().forEach {
-        val token = NameToken("data", it.name.toString())
-        set(token, it.meta)
+internal fun DataSet<*>.joinMeta(): Meta = Meta {
+    forEach { (key, data) ->
+        val token = NameToken("data", key.toString())
+        set(token, data.meta)
     }
 }
 
-public inline fun <T, reified R> DataTree<T>.reduceToData(
+public inline fun <T : Any, reified R : Any> DataSet<T>.reduceToData(
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     crossinline transformation: suspend (Iterable<NamedValueWithMeta<T>>) -> R,
-): Data<R> = asSequence().asIterable().reduceNamedToData(meta, coroutineContext, transformation)
+): Data<R> = asIterable().reduceNamedToData(meta, coroutineContext, transformation)
 
-public inline fun <T, reified R> DataTree<T>.foldToData(
+public inline fun <T : Any, reified R : Any> DataSet<T>.foldToData(
     initial: R,
     meta: Meta = joinMeta(),
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     crossinline block: suspend (result: R, data: NamedValueWithMeta<T>) -> R,
-): Data<R> = asSequence().asIterable().foldNamedToData(initial, meta, coroutineContext, block)
+): Data<R> = asIterable().foldNamedToData(initial, meta, coroutineContext, block)

dataforge-data/src/jvmMain/kotlin/space/kscience/dataforge/data/dataFilterJvm.kt

@@ -1,10 +1,12 @@
 package space.kscience.dataforge.data
 
-import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.filter
-import space.kscience.dataforge.misc.DFInternal
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.misc.DFExperimental
 import space.kscience.dataforge.names.Name
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
 import kotlin.reflect.KType
 import kotlin.reflect.full.isSubtypeOf
 import kotlin.reflect.typeOf
@@ -14,7 +16,7 @@ import kotlin.reflect.typeOf
  * Cast the node to given type if the cast is possible or return null
  */
 @Suppress("UNCHECKED_CAST")
-private fun <R> Data<*>.castOrNull(type: KType): Data<R>? =
+private fun <R : Any> Data<*>.castOrNull(type: KType): Data<R>? =
     if (!this.type.isSubtypeOf(type)) {
         null
     } else {
@@ -23,65 +25,61 @@ private fun <R> Data<*>.castOrNull(type: KType): Data<R>? =
         }
     }
 
-@Suppress("UNCHECKED_CAST")
-@DFInternal
-public fun <R> Sequence<NamedData<*>>.filterByDataType(type: KType): Sequence<NamedData<R>> =
-    filter { it.type.isSubtypeOf(type) } as Sequence<NamedData<R>>
-
-@Suppress("UNCHECKED_CAST")
-@DFInternal
-public fun <R> Flow<NamedData<*>>.filterByDataType(type: KType): Flow<NamedData<R>> =
-    filter { it.type.isSubtypeOf(type) } as Flow<NamedData<R>>
-
 /**
  * Select all data matching given type and filters. Does not modify paths
  *
- * @param predicate additional filtering condition based on item name and meta. By default, accepts all
+ * @param predicate addition filtering condition based on item name and meta. By default, accepts all
  */
-@DFInternal
-public fun <R> DataTree<*>.filterByType(
+@OptIn(DFExperimental::class)
+public fun <R : Any> DataSet<*>.filterByType(
     type: KType,
-    predicate: DataFilter = DataFilter.EMPTY,
-): DataTree<R> = asSequence().filterByDataType<R>(type).filterData(predicate).toTree(type)
+    predicate: (name: Name, meta: Meta) -> Boolean = { _, _ -> true },
+): DataSource<R> = object : DataSource<R> {
+    override val dataType = type
+
+    override val coroutineContext: CoroutineContext
+        get() = (this@filterByType as? DataSource)?.coroutineContext ?: EmptyCoroutineContext
+
+    override val meta: Meta get() = this@filterByType.meta
+
+    private fun checkDatum(name: Name, datum: Data<*>): Boolean = datum.type.isSubtypeOf(type)
+            && predicate(name, datum.meta)
+
+    override fun iterator(): Iterator<NamedData<R>> = iterator {
+        for(d in this@filterByType){
+            if(checkDatum(d.name,d.data)){
+                @Suppress("UNCHECKED_CAST")
+                yield(d as NamedData<R>)
+            }
+        }
+    }
+
+    override fun get(name: Name): Data<R>? = this@filterByType[name]?.let { datum ->
+        if (checkDatum(name, datum)) datum.castOrNull(type) else null
+    }
+
+    override val updates: Flow<Name> = this@filterByType.updates.filter { name ->
+        get(name)?.let { datum ->
+            checkDatum(name, datum)
+        } ?: false
+    }
+}
 
 /**
  * Select a single datum of the appropriate type
  */
-@OptIn(DFInternal::class)
-public inline fun <reified R : Any> DataTree<*>.filterByType(
-    predicate: DataFilter = DataFilter.EMPTY,
-): DataTree<R> = filterByType(typeOf<R>(), predicate)
+public inline fun <reified R : Any> DataSet<*>.filterByType(
+    noinline predicate: (name: Name, meta: Meta) -> Boolean = { _, _ -> true },
+): DataSet<R> = filterByType(typeOf<R>(), predicate)
 
 /**
  * Select a single datum if it is present and of given [type]
  */
-public fun <R> DataTree<*>.getByType(type: KType, name: Name): NamedData<R>? =
+public fun <R : Any> DataSet<*>.getByType(type: KType, name: Name): NamedData<R>? =
     get(name)?.castOrNull<R>(type)?.named(name)
 
-public inline fun <reified R : Any> DataTree<*>.getByType(name: Name): NamedData<R>? =
+public inline fun <reified R : Any> DataSet<*>.getByType(name: Name): NamedData<R>? =
     this@getByType.getByType(typeOf<R>(), name)
 
-public inline fun <reified R : Any> DataTree<*>.getByType(name: String): NamedData<R>? =
+public inline fun <reified R : Any> DataSet<*>.getByType(name: String): NamedData<R>? =
     this@getByType.getByType(typeOf<R>(), Name.parse(name))
-
-/**
- * Select all data matching given type and filters. Does not modify paths
- *
- * @param predicate additional filtering condition based on item name and meta. By default, accepts all
- */
-@DFInternal
-public fun <R> ObservableDataTree<*>.filterByType(
-    type: KType,
-    scope: CoroutineScope,
-    predicate: DataFilter = DataFilter.EMPTY,
-): ObservableDataTree<R> = asSequence()
-    .filterByDataType<R>(type)
-    .filterData(predicate)
-    .toObservableTree(type, scope, updates().filterByDataType<R>(type).filterData(predicate))
-
-
-@OptIn(DFInternal::class)
-public inline fun <reified R> ObservableDataTree<*>.filterByType(
-    scope: CoroutineScope,
-    predicate: DataFilter = DataFilter.EMPTY,
-): ObservableDataTree<R> = filterByType(typeOf<R>(),scope,predicate)

dataforge-data/src/jvmMain/kotlin/space/kscience/dataforge/data/dataSetBuilderInContext.kt

@@ -1,27 +1,40 @@
 package space.kscience.dataforge.data
 
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
 import space.kscience.dataforge.names.Name
+import space.kscience.dataforge.names.plus
 
 
 /**
  * Append data to node
  */
-context(DataSink<T>)
-public infix fun <T : Any> String.put(data: Data<T>): Unit =
-    put(Name.parse(this), data)
+context(DataSetBuilder<T>) public infix fun <T : Any> String.put(data: Data<T>): Unit =
+    data(Name.parse(this), data)
 
 /**
  * Append node
  */
-context(DataSink<T>)
-public infix fun <T : Any> String.put(dataSet: DataTree<T>): Unit =
-    branch(this, dataSet)
+context(DataSetBuilder<T>) public infix fun <T : Any> String.put(dataSet: DataSet<T>): Unit =
+    node(Name.parse(this), dataSet)
 
 /**
  * Build and append node
  */
-context(DataSink<T>)
-public infix fun <T : Any> String.put(
-    block: DataSink<T>.() -> Unit,
-): Unit = branch(Name.parse(this), block)
+context(DataSetBuilder<T>) public infix fun <T : Any> String.put(
+    block: DataSetBuilder<T>.() -> Unit,
+): Unit = node(Name.parse(this), block)
 
+/**
+ * Copy given data set and mirror its changes to this [DataTreeBuilder] in [this@setAndObserve]. Returns an update [Job]
+ */
+context(DataSetBuilder<T>) public fun <T : Any> CoroutineScope.setAndWatch(
+    name: Name,
+    dataSet: DataSet<T>,
+): Job = launch {
+    node(name, dataSet)
+    dataSet.updates.collect { nameInBranch ->
+        data(name + nameInBranch, dataSet.get(nameInBranch))
+    }
+}

dataforge-data/src/jvmTest/kotlin/space/kscience/dataforge/data/ActionsTest.kt

@@ -1,7 +1,7 @@
 package space.kscience.dataforge.data
 
+import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.test.runTest
 import org.junit.jupiter.api.Test
 import space.kscience.dataforge.actions.Action
@@ -10,13 +10,13 @@ import space.kscience.dataforge.actions.mapping
 import space.kscience.dataforge.misc.DFExperimental
 import kotlin.test.assertEquals
 
-@OptIn(DFExperimental::class)
+@OptIn(DFExperimental::class, ExperimentalCoroutinesApi::class)
 internal class ActionsTest {
     @Test
     fun testStaticMapAction() = runTest {
         val data: DataTree<Int> = DataTree {
             repeat(10) {
-                wrap(it.toString(), it)
+                static(it.toString(), it)
             }
         }
 
@@ -28,26 +28,23 @@ internal class ActionsTest {
     }
 
     @Test
-    fun testDynamicMapAction() = runBlocking {
-        val source: MutableDataTree<Int> = MutableDataTree()
+    fun testDynamicMapAction() = runTest {
+        val data: DataSourceBuilder<Int> = DataSource(this)
 
         val plusOne = Action.mapping<Int, Int> {
             result { it + 1 }
         }
 
-        val result = plusOne(source)
-
+        val result = plusOne(data)
 
         repeat(10) {
-            source.wrap(it.toString(), it)
+            data.static(it.toString(), it)
         }
 
-        delay(10)
-
-        source.close()
-        result.awaitClose()
+        delay(20)
 
         assertEquals(2, result["1"]?.await())
+        data.close()
     }
 
 }

dataforge-data/src/jvmTest/kotlin/space/kscience/dataforge/data/DataTreeBuilderTest.kt

@@ -1,8 +1,6 @@
 package space.kscience.dataforge.data
 
-import kotlinx.coroutines.delay
-import kotlinx.coroutines.runBlocking
-import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.*
 import space.kscience.dataforge.misc.DFExperimental
 import space.kscience.dataforge.names.asName
 import kotlin.test.Test
@@ -11,26 +9,27 @@ import kotlin.test.assertEquals
 
 internal class DataTreeBuilderTest {
     @Test
-    fun testTreeBuild() = runTest {
+    fun testTreeBuild() = runBlocking {
         val node = DataTree<Any> {
             "primary" put {
-                wrap("a", "a")
-                wrap("b", "b")
+                static("a", "a")
+                static("b", "b")
             }
-            wrap("c.d", "c.d")
-            wrap("c.f", "c.f")
+            static("c.d", "c.d")
+            static("c.f", "c.f")
+        }
+        runBlocking {
+            assertEquals("a", node["primary.a"]?.await())
+            assertEquals("b", node["primary.b"]?.await())
+            assertEquals("c.d", node["c.d"]?.await())
+            assertEquals("c.f", node["c.f"]?.await())
         }
-        assertEquals("a", node["primary.a"]?.await())
-        assertEquals("b", node["primary.b"]?.await())
-        assertEquals("c.d", node["c.d"]?.await())
-        assertEquals("c.f", node["c.f"]?.await())
-
     }
 
     @OptIn(DFExperimental::class)
     @Test
-    fun testDataUpdate() = runTest {
-        val updateData = DataTree<Any> {
+    fun testDataUpdate() = runBlocking {
+        val updateData: DataTree<Any> = DataTree {
             "update" put {
                 "a" put Data.static("a")
                 "b" put Data.static("b")
@@ -39,30 +38,54 @@ internal class DataTreeBuilderTest {
 
         val node = DataTree<Any> {
             "primary" put {
-                wrap("a", "a")
-                wrap("b", "b")
+                static("a", "a")
+                static("b", "b")
             }
-            wrap("root", "root")
-            putAll(updateData)
+            static("root", "root")
+            populateFrom(updateData)
         }
 
-        assertEquals("a", node["update.a"]?.await())
-        assertEquals("a", node["primary.a"]?.await())
+        runBlocking {
+            assertEquals("a", node["update.a"]?.await())
+            assertEquals("a", node["primary.a"]?.await())
+        }
     }
 
     @Test
     fun testDynamicUpdates() = runBlocking {
-        val subNode = MutableDataTree<Int>()
+        try {
+            lateinit var updateJob: Job
+            supervisorScope {
+                val subNode = DataSource<Int>(this) {
+                    updateJob = launch {
+                        repeat(10) {
+                            delay(10)
+                            static("value", it)
+                        }
+                        delay(10)
+                    }
+                }
+                launch {
+                    subNode.updatesWithData.collect {
+                        println(it)
+                    }
+                }
+                val rootNode = DataSource<Int>(this) {
+                    setAndWatch("sub".asName(), subNode)
+                }
 
-        val rootNode = MutableDataTree<Int> {
-            watchBranch("sub".asName(), subNode)
+                launch {
+                    rootNode.updatesWithData.collect {
+                        println(it)
+                    }
+                }
+                updateJob.join()
+                assertEquals(9, rootNode["sub.value"]?.await())
+                cancel()
+            }
+        } catch (t: Throwable) {
+            if (t !is CancellationException) throw t
         }
 
-        repeat(10) {
-            subNode.wrap("value[$it]", it)
-        }
-
-        delay(20)
-        assertEquals(9, rootNode["sub.value[9]"]?.await())
     }
 }

dataforge-io/build.gradle.kts

@@ -4,7 +4,7 @@ plugins {
 
 description = "IO module"
 
-val ioVersion = "0.3.1"
+val ioVersion = "0.3.0"
 
 kscience {
     jvm()

dataforge-io/src/commonMain/kotlin/space/kscience/dataforge/io/EnvelopeFormat.kt

@@ -10,7 +10,10 @@ import space.kscience.dataforge.names.asName
 import kotlin.reflect.KType
 import kotlin.reflect.typeOf
 
-public interface EnvelopeFormat : IOFormat<Envelope>
+public interface EnvelopeFormat : IOFormat<Envelope> {
+
+    override val type: KType get() = typeOf<Envelope>()
+}
 
 public fun EnvelopeFormat.read(input: Source): Envelope = readFrom(input)
 

dataforge-io/src/commonMain/kotlin/space/kscience/dataforge/io/IOFormat.kt

@@ -17,7 +17,11 @@ import kotlin.reflect.typeOf
 /**
  * Reader of a custom object from input
  */
-public fun interface IOReader<out T> {
+public interface IOReader<out T> {
+    /**
+     * The type of object being read
+     */
+    public val type: KType
 
     public fun readFrom(source: Source): T
 
@@ -28,6 +32,7 @@ public fun interface IOReader<out T> {
          * no-op reader for binaries.
          */
         public val binary: IOReader<Binary> = object : IOReader<Binary> {
+            override val type: KType = typeOf<Binary>()
 
             override fun readFrom(source: Source): Binary = source.readByteArray().asBinary()
 
@@ -37,6 +42,8 @@ public fun interface IOReader<out T> {
 }
 
 public inline fun <reified T> IOReader(crossinline read: Source.() -> T): IOReader<T> = object : IOReader<T> {
+    override val type: KType = typeOf<T>()
+
     override fun readFrom(source: Source): T = source.read()
 }
 
@@ -49,24 +56,24 @@ public fun interface IOWriter<in T> {
  */
 public interface IOFormat<T> : IOReader<T>, IOWriter<T>
 
-public fun <T> Source.readWith(format: IOReader<T>): T = format.readFrom(this)
+public fun <T : Any> Source.readWith(format: IOReader<T>): T = format.readFrom(this)
 
 /**
  * Read given binary as an object using given format
  */
-public fun <T> Binary.readWith(format: IOReader<T>): T = read {
-    this.readWith(format)
+public fun <T : Any> Binary.readWith(format: IOReader<T>): T = read {
+    readWith(format)
 }
 
 /**
  * Write an object to the [Sink] with given [format]
  */
-public fun <T> Sink.writeWith(format: IOWriter<T>, obj: T): Unit =
+public fun <T : Any> Sink.writeWith(format: IOWriter<T>, obj: T): Unit =
     format.writeTo(this, obj)
 
 
 @DfType(IO_FORMAT_TYPE)
-public interface IOFormatFactory<T> : Factory<IOFormat<T>>, Named {
+public interface IOFormatFactory<T : Any> : Factory<IOFormat<T>>, Named {
     /**
      * Explicit type for dynamic type checks
      */
@@ -79,7 +86,7 @@ public interface IOFormatFactory<T> : Factory<IOFormat<T>>, Named {
     }
 }
 
-public fun <T> Binary(obj: T, format: IOWriter<T>): Binary = Binary { format.writeTo(this, obj) }
+public fun <T : Any> Binary(obj: T, format: IOWriter<T>): Binary = Binary { format.writeTo(this, obj) }
 
 public object FloatIOFormat : IOFormat<Float>, IOFormatFactory<Float> {
     override fun build(context: Context, meta: Meta): IOFormat<Float> = this

dataforge-io/src/commonMain/kotlin/space/kscience/dataforge/io/IOPlugin.kt

@@ -5,6 +5,7 @@ import space.kscience.dataforge.io.EnvelopeFormatFactory.Companion.ENVELOPE_FORM
 import space.kscience.dataforge.io.IOFormatFactory.Companion.IO_FORMAT_TYPE
 import space.kscience.dataforge.io.MetaFormatFactory.Companion.META_FORMAT_TYPE
 import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.meta.get
 import space.kscience.dataforge.meta.string
 import space.kscience.dataforge.misc.DFInternal
 import space.kscience.dataforge.names.Name
@@ -20,11 +21,11 @@ public class IOPlugin(meta: Meta) : AbstractPlugin(meta) {
 
     @Suppress("UNCHECKED_CAST")
     @DFInternal
-    public fun <T> resolveIOFormat(type: KType, meta: Meta): IOFormat<T>? =
+    public fun <T : Any> resolveIOFormat(type: KType, meta: Meta): IOFormat<T>? =
         ioFormatFactories.singleOrNull { it.type == type }?.build(context, meta) as? IOFormat<T>
 
     @OptIn(DFInternal::class)
-    public inline fun <reified T> resolveIOFormat(meta: Meta = Meta.EMPTY): IOFormat<T>? =
+    public inline fun <reified T : Any> resolveIOFormat(meta: Meta = Meta.EMPTY): IOFormat<T>? =
         resolveIOFormat(typeOf<T>(), meta)
 
 

dataforge-io/src/commonMain/kotlin/space/kscience/dataforge/io/MetaFormat.kt

@@ -21,6 +21,8 @@ import kotlin.reflect.typeOf
  */
 public interface MetaFormat : IOFormat<Meta> {
 
+    override val type: KType get() = typeOf<Meta>()
+
     override fun writeTo(sink: Sink, obj: Meta) {
         writeMeta(sink, obj, null)
     }

dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/meta/MetaConverter.kt

@@ -6,6 +6,8 @@ import kotlinx.serialization.json.encodeToJsonElement
 import kotlinx.serialization.serializer
 import space.kscience.dataforge.meta.descriptors.MetaDescriptor
 import space.kscience.dataforge.misc.DFExperimental
+import kotlin.reflect.KType
+import kotlin.reflect.typeOf
 
 
 /**
@@ -13,10 +15,15 @@ import space.kscience.dataforge.misc.DFExperimental
  */
 public interface MetaConverter<T>: MetaSpec<T> {
 
+    /**
+     * Runtime type of [T]
+     */
+    public val type: KType
+
     /**
      * A descriptor for resulting meta
      */
-    override val descriptor: MetaDescriptor? get() = null
+    override val descriptor: MetaDescriptor get() = MetaDescriptor.EMPTY
 
     /**
      * Attempt conversion of [source] to an object or return null if conversion failed
@@ -31,16 +38,22 @@ public interface MetaConverter<T>: MetaSpec<T> {
     public companion object {
 
         public val meta: MetaConverter<Meta> = object : MetaConverter<Meta> {
+            override val type: KType = typeOf<Meta>()
+
             override fun readOrNull(source: Meta): Meta = source
             override fun convert(obj: Meta): Meta = obj
         }
 
         public val value: MetaConverter<Value> = object : MetaConverter<Value> {
+            override val type: KType = typeOf<Value>()
+
             override fun readOrNull(source: Meta): Value? = source.value
             override fun convert(obj: Value): Meta = Meta(obj)
         }
 
         public val string: MetaConverter<String> = object : MetaConverter<String> {
+            override val type: KType = typeOf<String>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.STRING)
             }
@@ -51,6 +64,8 @@ public interface MetaConverter<T>: MetaSpec<T> {
         }
 
         public val boolean: MetaConverter<Boolean> = object : MetaConverter<Boolean> {
+            override val type: KType = typeOf<Boolean>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.BOOLEAN)
             }
@@ -60,6 +75,8 @@ public interface MetaConverter<T>: MetaSpec<T> {
         }
 
         public val number: MetaConverter<Number> = object : MetaConverter<Number> {
+            override val type: KType = typeOf<Number>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.NUMBER)
             }
@@ -69,6 +86,8 @@ public interface MetaConverter<T>: MetaSpec<T> {
         }
 
         public val double: MetaConverter<Double> = object : MetaConverter<Double> {
+            override val type: KType = typeOf<Double>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.NUMBER)
             }
@@ -78,6 +97,8 @@ public interface MetaConverter<T>: MetaSpec<T> {
         }
 
         public val float: MetaConverter<Float> = object : MetaConverter<Float> {
+            override val type: KType = typeOf<Float>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.NUMBER)
             }
@@ -87,6 +108,8 @@ public interface MetaConverter<T>: MetaSpec<T> {
         }
 
         public val int: MetaConverter<Int> = object : MetaConverter<Int> {
+            override val type: KType = typeOf<Int>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.NUMBER)
             }
@@ -96,6 +119,8 @@ public interface MetaConverter<T>: MetaSpec<T> {
         }
 
         public val long: MetaConverter<Long> = object : MetaConverter<Long> {
+            override val type: KType = typeOf<Long>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.NUMBER)
             }
@@ -105,6 +130,8 @@ public interface MetaConverter<T>: MetaSpec<T> {
         }
 
         public inline fun <reified E : Enum<E>> enum(): MetaConverter<E> = object : MetaConverter<E> {
+            override val type: KType = typeOf<E>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.STRING)
                 allowedValues(enumValues<E>())
@@ -120,6 +147,8 @@ public interface MetaConverter<T>: MetaSpec<T> {
             writer: (T) -> Value = { Value.of(it) },
             reader: (Value) -> T,
         ): MetaConverter<List<T>> = object : MetaConverter<List<T>> {
+            override val type: KType = typeOf<List<T>>()
+
             override val descriptor: MetaDescriptor = MetaDescriptor {
                 valueType(ValueType.LIST)
             }
@@ -136,6 +165,7 @@ public interface MetaConverter<T>: MetaSpec<T> {
         public inline fun <reified T> serializable(
             descriptor: MetaDescriptor? = null,
         ): MetaConverter<T> = object : MetaConverter<T> {
+            override val type: KType = typeOf<T>()
             private val serializer: KSerializer<T> = serializer()
 
             override fun readOrNull(source: Meta): T? {

dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/meta/Scheme.kt

@@ -166,9 +166,9 @@ public inline fun <T : Scheme> T.copy(spec: SchemeSpec<T>, block: T.() -> Unit =
 /**
  * A specification for simplified generation of wrappers
  */
-public open class SchemeSpec<T : Scheme>(
+public open class SchemeSpec<out T : Scheme>(
     private val builder: () -> T,
-) : MetaConverter<T> {
+) : MetaSpec<T> {
 
     override val descriptor: MetaDescriptor? get() = null
 
@@ -187,8 +187,6 @@ public open class SchemeSpec<T : Scheme>(
         it.initialize(MutableMeta(), Meta.EMPTY, descriptor)
     }
 
-    override fun convert(obj: T): Meta  = obj.meta
-
     /**
      * A convenience method to use specifications in builders
      */

dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/names/Name.kt

@@ -113,13 +113,6 @@ public class Name(public val tokens: List<NameToken>) {
     }
 }
 
-/**
- * Transform this [Name] to a string without escaping special characters in tokens.
- *
- * Parsing it back will produce a valid, but different name
- */
-public fun Name.toStringUnescaped(): String = tokens.joinToString(separator = Name.NAME_SEPARATOR) { it.toStringUnescaped() }
-
 public operator fun Name.get(i: Int): NameToken = tokens[i]
 
 /**

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/EnvelopeTask.kt

@@ -0,0 +1,46 @@
+package space.kscience.dataforge.workspace
+
+import space.kscience.dataforge.data.DataTree.Companion.META_ITEM_NAME_TOKEN
+import space.kscience.dataforge.io.Envelope
+import space.kscience.dataforge.io.IOReader
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.meta.descriptors.MetaDescriptor
+import space.kscience.dataforge.names.Name
+import space.kscience.dataforge.names.asName
+import kotlin.reflect.KType
+
+public abstract class EnvelopeTask<T : Any>(
+    override val descriptor: MetaDescriptor?,
+    private val reader: IOReader<T>,
+) : Task<T> {
+
+    public abstract suspend fun produceEnvelopes(
+        workspace: Workspace,
+        taskName: Name,
+        taskMeta: Meta,
+    ): Map<Name, Envelope>
+
+    override suspend fun execute(workspace: Workspace, taskName: Name, taskMeta: Meta): TaskResult<T> =
+        Result(workspace, taskName, taskMeta, reader, produceEnvelopes(workspace, taskName, taskMeta))
+
+    private class Result<T : Any>(
+        override val workspace: Workspace,
+        override val taskName: Name,
+        override val taskMeta: Meta,
+        val reader: IOReader<T>,
+        envelopes: Map<Name, Envelope>,
+    ) : TaskResult<T> {
+
+        private val dataMap = envelopes.mapValues {
+            workspace.wrapData(it.value.toData(reader), it.key, taskName, taskMeta)
+        }
+        override val meta: Meta get() = dataMap[META_ITEM_NAME_TOKEN.asName()]?.meta ?: Meta.EMPTY
+
+        override val dataType: KType get() = reader.type
+
+        override fun iterator(): Iterator<TaskData<T>> = dataMap.values.iterator()
+
+        override fun get(name: Name): TaskData<T>? = dataMap[name]
+    }
+}
+

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/Task.kt

@@ -1,9 +1,9 @@
 package space.kscience.dataforge.workspace
 
 import kotlinx.coroutines.withContext
-import space.kscience.dataforge.data.DataSink
+import space.kscience.dataforge.data.DataSetBuilder
+import space.kscience.dataforge.data.DataTree
 import space.kscience.dataforge.data.GoalExecutionRestriction
-import space.kscience.dataforge.data.MutableDataTree
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.meta.MetaRepr
 import space.kscience.dataforge.meta.MetaSpec
@@ -20,7 +20,7 @@ import kotlin.reflect.typeOf
  * In general no computations should be made until the result is called.
  */
 @DfType(TYPE)
-public interface Task<T> : Described {
+public interface Task<out T : Any> : Described {
 
     /**
      * A task identification string used to compare tasks and check task body for change
@@ -45,7 +45,7 @@ public interface Task<T> : Described {
 /**
  * A [Task] with [MetaSpec] for wrapping and unwrapping task configuration
  */
-public interface TaskWithSpec<T, C : Any> : Task<T> {
+public interface TaskWithSpec<out T : Any, C : Any> : Task<T> {
     public val spec: MetaSpec<C>
     override val descriptor: MetaDescriptor? get() = spec.descriptor
 
@@ -61,12 +61,12 @@ public interface TaskWithSpec<T, C : Any> : Task<T> {
 //    block: C.() -> Unit = {},
 //): TaskResult<T> = execute(workspace, taskName, spec(block))
 
-public class TaskResultBuilder<T>(
+public class TaskResultBuilder<in T : Any>(
     public val workspace: Workspace,
     public val taskName: Name,
     public val taskMeta: Meta,
-    private val dataSink: DataSink<T>,
-) : DataSink<T> by dataSink
+    private val dataDrop: DataSetBuilder<T>,
+) : DataSetBuilder<T> by dataDrop
 
 /**
  * Create a [Task] that composes a result using [builder]. Only data from the workspace could be used.
@@ -88,17 +88,12 @@ public fun <T : Any> Task(
         workspace: Workspace,
         taskName: Name,
         taskMeta: Meta,
-    ): TaskResult<T> {
+    ): TaskResult<T> = withContext(GoalExecutionRestriction() + workspace.goalLogger) {
         //TODO use safe builder and check for external data on add and detects cycles
-        val dataset = MutableDataTree<T>(resultType, workspace.context).apply {
-            TaskResultBuilder(workspace, taskName, taskMeta, this).apply {
-                withContext(GoalExecutionRestriction() + workspace.goalLogger) {
-                    builder()
-                }
-            }
+        val dataset = DataTree<T>(resultType) {
+            TaskResultBuilder(workspace, taskName, taskMeta, this).apply { builder() }
         }
-        return workspace.wrapResult(dataset, taskName, taskMeta)
-
+        workspace.wrapResult(dataset, taskName, taskMeta)
     }
 }
 
@@ -116,7 +111,6 @@ public inline fun <reified T : Any> Task(
  * @param specification a specification for task configuration
  * @param builder for resulting data set
  */
-
 @Suppress("FunctionName")
 public fun <T : Any, C : MetaRepr> Task(
     resultType: KType,
@@ -132,7 +126,7 @@ public fun <T : Any, C : MetaRepr> Task(
     ): TaskResult<T> = withContext(GoalExecutionRestriction() + workspace.goalLogger) {
         //TODO use safe builder and check for external data on add and detects cycles
         val taskMeta = configuration.toMeta()
-        val dataset = MutableDataTree<T>(resultType, this).apply {
+        val dataset = DataTree<T>(resultType) {
             TaskResultBuilder(workspace, taskName, taskMeta, this).apply { builder(configuration) }
         }
         workspace.wrapResult(dataset, taskName, taskMeta)

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/TaskData.kt

@@ -0,0 +1,50 @@
+package space.kscience.dataforge.workspace
+
+import space.kscience.dataforge.data.Data
+import space.kscience.dataforge.data.NamedData
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.names.Name
+
+/**
+ * A [Workspace]-locked [NamedData], that serves as a computation model.
+ */
+public interface TaskData<out T : Any> : NamedData<T> {
+    /**
+     * The [Workspace] this data belongs to
+     */
+    public val workspace: Workspace
+
+    /**
+     * The name of the stage that produced this data. [Name.EMPTY] if the workspace intrinsic data is used.
+     */
+    public val taskName: Name
+
+    /**
+     * Stage configuration used to produce this data.
+     */
+    public val taskMeta: Meta
+
+    /**
+     * Dependencies that allow to compute transitive dependencies as well.
+     */
+//    override val dependencies: Collection<TaskData<*>>
+}
+
+private class TaskDataImpl<out T : Any>(
+    override val workspace: Workspace,
+    override val data: Data<T>,
+    override val name: Name,
+    override val taskName: Name,
+    override val taskMeta: Meta,
+) : TaskData<T>, Data<T> by data {
+//    override val dependencies: Collection<TaskData<*>> = data.dependencies.map {
+//        it as? TaskData<*> ?: error("TaskData can't depend on external data")
+//    }
+}
+
+/**
+ * Adopt data into this workspace
+ */
+public fun <T : Any> Workspace.wrapData(data: Data<T>, name: Name, taskName: Name, taskMeta: Meta): TaskData<T> =
+    TaskDataImpl(this, data, name, taskName, taskMeta)
+

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/TaskResult.kt

@@ -1,41 +1,54 @@
 package space.kscience.dataforge.workspace
 
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Job
-import kotlinx.coroutines.joinAll
-import kotlinx.coroutines.launch
-import space.kscience.dataforge.data.ObservableDataTree
-import space.kscience.dataforge.data.asSequence
-import space.kscience.dataforge.data.launch
+import space.kscience.dataforge.data.DataSet
+import space.kscience.dataforge.data.forEach
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.names.Name
 
 /**
  * A result of a [Task]
- * @param workspace the [Workspace] that produced the result
- * @param taskName the name of the task that produced the result
- * @param taskMeta The configuration of the task that produced the result
  */
-public data class TaskResult<T>(
-    public val content: ObservableDataTree<T>,
-    public val workspace: Workspace,
-    public val taskName: Name,
-    public val taskMeta: Meta,
-) : ObservableDataTree<T> by content
+public interface TaskResult<out T : Any> : DataSet<T> {
+    /**
+     * The [Workspace] this [DataSet] belongs to
+     */
+    public val workspace: Workspace
+
+    /**
+     * The [Name] of the stage that produced this [DataSet]
+     */
+    public val taskName: Name
+
+    /**
+     * The configuration of the stage that produced this [DataSet]
+     */
+    public val taskMeta: Meta
+
+    override fun iterator(): Iterator<TaskData<T>>
+
+    override fun get(name: Name): TaskData<T>?
+}
+
+private class TaskResultImpl<out T : Any>(
+    override val workspace: Workspace,
+    override val taskName: Name,
+    override val taskMeta: Meta,
+    val dataSet: DataSet<T>,
+) : TaskResult<T>, DataSet<T> by dataSet {
+
+    override fun iterator(): Iterator<TaskData<T>> = iterator {
+        dataSet.forEach {
+            yield(workspace.wrapData(it, it.name, taskName, taskMeta))
+        }
+    }
+
+    override fun get(name: Name): TaskData<T>? = dataSet[name]?.let {
+        workspace.wrapData(it, name, taskName, taskMeta)
+    }
+}
 
 /**
  * Wrap data into [TaskResult]
  */
-public fun <T> Workspace.wrapResult(data: ObservableDataTree<T>, taskName: Name, taskMeta: Meta): TaskResult<T> =
-    TaskResult(data, this, taskName, taskMeta)
-
-/**
- * Start computation for all data elements of this node.
- * The resulting [Job] is completed only when all of them are completed.
- */
-public fun TaskResult<*>.launch(scope: CoroutineScope): Job {
-    val jobs = asSequence().map {
-        it.data.launch(scope)
-    }.toList()
-    return scope.launch { jobs.joinAll() }
-}
+public fun <T : Any> Workspace.wrapResult(dataSet: DataSet<T>, taskName: Name, taskMeta: Meta): TaskResult<T> =
+    TaskResultImpl(this, taskName, taskMeta, dataSet)

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/Workspace.kt

@@ -1,32 +1,29 @@
 package space.kscience.dataforge.workspace
 
-import kotlinx.coroutines.CoroutineScope
 import space.kscience.dataforge.context.ContextAware
-import space.kscience.dataforge.data.*
+import space.kscience.dataforge.data.Data
+import space.kscience.dataforge.data.DataSet
+import space.kscience.dataforge.data.asSequence
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.meta.MutableMeta
 import space.kscience.dataforge.misc.DfType
 import space.kscience.dataforge.names.Name
 import space.kscience.dataforge.provider.Provider
-import kotlin.coroutines.CoroutineContext
 
 
-public fun interface DataSelector<T> {
-    public suspend fun select(workspace: Workspace, meta: Meta): DataTree<T>
+public interface DataSelector<T: Any>{
+    public suspend fun select(workspace: Workspace, meta: Meta): DataSet<T>
 }
 
 /**
  * An environment for pull-mode computation
  */
 @DfType(Workspace.TYPE)
-public interface Workspace : ContextAware, Provider, CoroutineScope {
-
-    override val coroutineContext: CoroutineContext get() = context.coroutineContext
-
+public interface Workspace : ContextAware, Provider {
     /**
      * The whole data node for current workspace
      */
-    public val data: ObservableDataTree<*>
+    public val data: TaskResult<*>
 
     /**
      * All targets associated with the workspace
@@ -40,7 +37,7 @@ public interface Workspace : ContextAware, Provider, CoroutineScope {
 
     override fun content(target: String): Map<Name, Any> {
         return when (target) {
-            "target", Meta.TYPE -> targets.mapKeys { Name.parse(it.key) }
+            "target", Meta.TYPE -> targets.mapKeys { Name.parse(it.key)}
             Task.TYPE -> tasks
             Data.TYPE -> data.asSequence().associateBy { it.name }
             else -> emptyMap()
@@ -52,7 +49,7 @@ public interface Workspace : ContextAware, Provider, CoroutineScope {
         return task.execute(this, taskName, taskMeta)
     }
 
-    public suspend fun produceData(taskName: Name, taskMeta: Meta, name: Name): Data<*>? =
+    public suspend fun produceData(taskName: Name, taskMeta: Meta, name: Name): TaskData<*>? =
         produce(taskName, taskMeta)[name]
 
     public companion object {

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/WorkspaceBuilder.kt

@@ -5,9 +5,9 @@ import space.kscience.dataforge.actions.Action
 import space.kscience.dataforge.context.Context
 import space.kscience.dataforge.context.ContextBuilder
 import space.kscience.dataforge.context.Global
-import space.kscience.dataforge.data.DataSink
-import space.kscience.dataforge.data.DataTree
-import space.kscience.dataforge.data.MutableDataTree
+import space.kscience.dataforge.data.DataSet
+import space.kscience.dataforge.data.DataSource
+import space.kscience.dataforge.data.DataSourceBuilder
 import space.kscience.dataforge.meta.*
 import space.kscience.dataforge.meta.descriptors.MetaDescriptor
 import space.kscience.dataforge.meta.descriptors.MetaDescriptorBuilder
@@ -17,14 +17,13 @@ import space.kscience.dataforge.names.asName
 import kotlin.collections.set
 import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadOnlyProperty
-import kotlin.reflect.typeOf
 
-public data class TaskReference<T>(public val taskName: Name, public val task: Task<T>) : DataSelector<T> {
+public data class TaskReference<T : Any>(public val taskName: Name, public val task: Task<T>) : DataSelector<T> {
 
     @Suppress("UNCHECKED_CAST")
-    override suspend fun select(workspace: Workspace, meta: Meta): DataTree<T> {
+    override suspend fun select(workspace: Workspace, meta: Meta): DataSet<T> {
         if (workspace.tasks[taskName] == task) {
-            return workspace.produce(taskName, meta) as DataTree<T>
+            return workspace.produce(taskName, meta) as TaskResult<T>
         } else {
             error("Task $taskName does not belong to the workspace")
         }
@@ -46,7 +45,7 @@ public inline fun <reified T : Any> TaskContainer.registerTask(
 ): Unit = registerTask(Name.parse(name), Task(MetaDescriptor(descriptorBuilder), builder))
 
 /**
- * Create and register a new task
+ * Create a new t
  */
 public inline fun <reified T : Any> TaskContainer.buildTask(
     name: String,
@@ -110,7 +109,7 @@ public class WorkspaceBuilder(
     private val coroutineScope: CoroutineScope = parentContext,
 ) : TaskContainer {
     private var context: Context? = null
-    private val data = MutableDataTree<Any?>(typeOf<Any?>(), coroutineScope)
+    private val data = DataSource<Any>(coroutineScope)
     private val targets: HashMap<String, Meta> = HashMap()
     private val tasks = HashMap<Name, Task<*>>()
     private var cache: WorkspaceCache? = null
@@ -125,7 +124,7 @@ public class WorkspaceBuilder(
     /**
      * Define intrinsic data for the workspace
      */
-    public fun data(builder: DataSink<Any?>.() -> Unit) {
+    public fun data(builder: DataSourceBuilder<Any>.() -> Unit) {
         data.apply(builder)
     }
 
@@ -150,7 +149,7 @@ public class WorkspaceBuilder(
 
     public fun build(): Workspace {
         val postProcess: suspend (TaskResult<*>) -> TaskResult<*> = { result ->
-            cache?.cache(result) ?: result
+            cache?.evaluate(result) ?: result
         }
         return WorkspaceImpl(context ?: parentContext, data, targets, tasks, postProcess)
     }

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/WorkspaceCache.kt

@@ -1,5 +1,5 @@
 package space.kscience.dataforge.workspace
 
 public interface WorkspaceCache {
-    public suspend fun <T> cache(result: TaskResult<T>): TaskResult<T>
+    public suspend fun <T : Any> evaluate(result: TaskResult<T>): TaskResult<T>
 }

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/WorkspaceImpl.kt

@@ -2,19 +2,21 @@ package space.kscience.dataforge.workspace
 
 import space.kscience.dataforge.context.Context
 import space.kscience.dataforge.context.gather
-import space.kscience.dataforge.data.ObservableDataTree
+import space.kscience.dataforge.data.DataSet
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.names.Name
 
 
 internal class WorkspaceImpl internal constructor(
     override val context: Context,
-    override val data: ObservableDataTree<*>,
+    data: DataSet<*>,
     override val targets: Map<String, Meta>,
     tasks: Map<Name, Task<*>>,
     private val postProcess: suspend (TaskResult<*>) -> TaskResult<*>,
 ) : Workspace {
 
+    override val data: TaskResult<*> = wrapResult(data, Name.EMPTY, Meta.EMPTY)
+
     override val tasks: Map<Name, Task<*>> by lazy { context.gather<Task<*>>(Task.TYPE) + tasks }
 
     override suspend fun produce(taskName: Name, taskMeta: Meta): TaskResult<*> {

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/envelopeData.kt

@@ -4,14 +4,13 @@ import space.kscience.dataforge.data.Data
 import space.kscience.dataforge.data.await
 import space.kscience.dataforge.io.*
 import space.kscience.dataforge.misc.DFInternal
-import kotlin.reflect.typeOf
 
 
 /**
  * Convert an [Envelope] to a data via given format. The actual parsing is done lazily.
  */
 @OptIn(DFInternal::class)
-public inline fun <reified T : Any> Envelope.toData(format: IOReader<T>): Data<T> = Data(typeOf<T>(), meta) {
+public fun <T : Any> Envelope.toData(format: IOReader<T>): Data<T> = Data(format.type, meta) {
     data?.readWith(format) ?: error("Can't convert envelope without data to Data")
 }
 

dataforge-workspace/src/commonMain/kotlin/space/kscience/dataforge/workspace/taskBuilders.kt

@@ -2,10 +2,9 @@ package space.kscience.dataforge.workspace
 
 import space.kscience.dataforge.actions.Action
 import space.kscience.dataforge.context.PluginFactory
-import space.kscience.dataforge.data.DataTree
-import space.kscience.dataforge.data.branch
+import space.kscience.dataforge.data.DataSet
 import space.kscience.dataforge.data.forEach
-import space.kscience.dataforge.data.transform
+import space.kscience.dataforge.data.map
 import space.kscience.dataforge.meta.*
 import space.kscience.dataforge.misc.DFExperimental
 import space.kscience.dataforge.names.Name
@@ -25,22 +24,22 @@ public val TaskResultBuilder<*>.defaultDependencyMeta: Meta
  * @param selector a workspace data selector. Could be either task selector or initial data selector.
  * @param dependencyMeta meta used for selector. The same meta is used for caching. By default, uses [defaultDependencyMeta].
  */
-public suspend fun <T> TaskResultBuilder<*>.from(
+public suspend fun <T : Any> TaskResultBuilder<*>.from(
     selector: DataSelector<T>,
     dependencyMeta: Meta = defaultDependencyMeta,
-): DataTree<T> = selector.select(workspace, dependencyMeta)
+): DataSet<T> = selector.select(workspace, dependencyMeta)
 
-public suspend inline fun <T, reified P : WorkspacePlugin> TaskResultBuilder<*>.from(
+public suspend inline fun <T : Any, reified P : WorkspacePlugin> TaskResultBuilder<*>.from(
     plugin: P,
     dependencyMeta: Meta = defaultDependencyMeta,
     selectorBuilder: P.() -> TaskReference<T>,
-): TaskResult<T> {
+): DataSet<T> {
     require(workspace.context.plugins.contains(plugin)) { "Plugin $plugin is not loaded into $workspace" }
     val taskReference: TaskReference<T> = plugin.selectorBuilder()
     val res = workspace.produce(plugin.name + taskReference.taskName, dependencyMeta)
     //TODO add explicit check after https://youtrack.jetbrains.com/issue/KT-32956
     @Suppress("UNCHECKED_CAST")
-    return res as TaskResult<T>
+    return  res as TaskResult<T>
 }
 
 /**
@@ -50,11 +49,11 @@ public suspend inline fun <T, reified P : WorkspacePlugin> TaskResultBuilder<*>.
  * @param dependencyMeta meta used for selector. The same meta is used for caching. By default, uses [defaultDependencyMeta].
  * @param selectorBuilder a builder of task from the plugin.
  */
-public suspend inline fun <reified T, reified P : WorkspacePlugin> TaskResultBuilder<*>.from(
+public suspend inline fun <reified T : Any, reified P : WorkspacePlugin> TaskResultBuilder<*>.from(
     pluginFactory: PluginFactory<P>,
     dependencyMeta: Meta = defaultDependencyMeta,
     selectorBuilder: P.() -> TaskReference<T>,
-): TaskResult<T> {
+): DataSet<T> {
     val plugin = workspace.context.plugins[pluginFactory]
         ?: error("Plugin ${pluginFactory.tag} not loaded into workspace context")
     val taskReference: TaskReference<T> = plugin.selectorBuilder()
@@ -65,7 +64,9 @@ public suspend inline fun <reified T, reified P : WorkspacePlugin> TaskResultBui
 }
 
 public val TaskResultBuilder<*>.allData: DataSelector<*>
-    get() = DataSelector { workspace, _ -> workspace.data }
+    get() = object : DataSelector<Any> {
+        override suspend fun select(workspace: Workspace, meta: Meta): DataSet<Any> = workspace.data
+    }
 
 /**
  * Perform a lazy mapping task using given [selector] and one-to-one [action].
@@ -77,7 +78,7 @@ public val TaskResultBuilder<*>.allData: DataSelector<*>
  * @param action process individual data asynchronously.
  */
 @DFExperimental
-public suspend inline fun <T, reified R> TaskResultBuilder<R>.transformEach(
+public suspend inline fun <T : Any, reified R : Any> TaskResultBuilder<R>.transformEach(
     selector: DataSelector<T>,
     dependencyMeta: Meta = defaultDependencyMeta,
     dataMetaTransform: MutableMeta.(name: Name) -> Unit = {},
@@ -89,31 +90,31 @@ public suspend inline fun <T, reified R> TaskResultBuilder<R>.transformEach(
             dataMetaTransform(data.name)
         }
 
-        val res = data.transform(meta, workspace.context.coroutineContext) {
+        val res = data.map(meta, workspace.context.coroutineContext) {
             action(it, data.name, meta)
         }
 
-        put(data.name, res)
+        data(data.name, res)
     }
 }
 
 /**
  * Set given [dataSet] as a task result.
  */
-public fun <T> TaskResultBuilder<T>.result(dataSet: DataTree<T>) {
-    branch(dataSet)
+public fun <T : Any> TaskResultBuilder<T>.result(dataSet: DataSet<T>) {
+    node(Name.EMPTY, dataSet)
 }
 
 /**
  * Use provided [action] to fill the result
  */
 @DFExperimental
-public suspend inline fun <T, reified R> TaskResultBuilder<R>.actionFrom(
+public suspend inline fun <T : Any, reified R : Any> TaskResultBuilder<R>.actionFrom(
     selector: DataSelector<T>,
-    action: Action<T, R>,
+    action: Action<T,R>,
     dependencyMeta: Meta = defaultDependencyMeta,
 ) {
-    branch(action.execute(from(selector, dependencyMeta), dependencyMeta))
+    node(Name.EMPTY, action.execute(from(selector,dependencyMeta), dependencyMeta))
 }
 
 

dataforge-workspace/src/jvmMain/kotlin/space/kscience/dataforge/workspace/FileWorkspaceCache.kt

@@ -1,6 +1,5 @@
 package space.kscience.dataforge.workspace
 
-import kotlinx.coroutines.flow.map
 import kotlinx.io.*
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.KSerializer
@@ -10,10 +9,12 @@ import kotlinx.serialization.serializer
 import space.kscience.dataforge.context.error
 import space.kscience.dataforge.context.logger
 import space.kscience.dataforge.context.request
-import space.kscience.dataforge.data.*
+import space.kscience.dataforge.data.Data
+import space.kscience.dataforge.data.await
 import space.kscience.dataforge.io.*
 import space.kscience.dataforge.misc.DFExperimental
 import space.kscience.dataforge.misc.DFInternal
+import space.kscience.dataforge.names.Name
 import space.kscience.dataforge.names.withIndex
 import java.nio.file.Path
 import kotlin.io.path.deleteIfExists
@@ -21,7 +22,7 @@ import kotlin.io.path.div
 import kotlin.io.path.exists
 import kotlin.reflect.KType
 
-public class JsonIOFormat<T>(private val type: KType) : IOFormat<T> {
+public class JsonIOFormat<T : Any>(override val type: KType) : IOFormat<T> {
 
     @Suppress("UNCHECKED_CAST")
     private val serializer: KSerializer<T> = serializer(type) as KSerializer<T>
@@ -34,7 +35,7 @@ public class JsonIOFormat<T>(private val type: KType) : IOFormat<T> {
 }
 
 @OptIn(ExperimentalSerializationApi::class)
-public class ProtobufIOFormat<T>(private val type: KType) : IOFormat<T> {
+public class ProtobufIOFormat<T : Any>(override val type: KType) : IOFormat<T> {
 
     @Suppress("UNCHECKED_CAST")
     private val serializer: KSerializer<T> = serializer(type) as KSerializer<T>
@@ -52,14 +53,14 @@ public class FileWorkspaceCache(public val cacheDirectory: Path) : WorkspaceCach
     //    private fun <T : Any> TaskData<*>.checkType(taskType: KType): TaskData<T> = this as TaskData<T>
 
     @OptIn(DFExperimental::class, DFInternal::class)
-    override suspend fun <T> cache(result: TaskResult<T>): TaskResult<T> {
+    override suspend fun <T : Any> evaluate(result: TaskResult<T>): TaskResult<T> {
         val io = result.workspace.context.request(IOPlugin)
 
         val format: IOFormat<T> = io.resolveIOFormat(result.dataType, result.taskMeta)
             ?: ProtobufIOFormat(result.dataType)
             ?: error("Can't resolve IOFormat for ${result.dataType}")
 
-        fun cacheOne(data: NamedData<T>): NamedData<T> {
+        fun evaluateDatum(data: TaskData<T>): TaskData<T> {
 
             val path = cacheDirectory /
                     result.taskName.withIndex(result.taskMeta.hashCode().toString(16)).toString() /
@@ -91,14 +92,15 @@ public class FileWorkspaceCache(public val cacheDirectory: Path) : WorkspaceCach
                 }
 
             }
-            return datum.named(data.name)
+            return data.workspace.wrapData(datum, data.name, data.taskName, data.taskMeta)
         }
 
+        return object : TaskResult<T> by result {
+            override fun iterator(): Iterator<TaskData<T>> =
+                result.iterator().asSequence().map { evaluateDatum(it) }.iterator()
 
-        val cachedTree = result.asSequence().map { cacheOne(it) }
-            .toObservableTree(result.dataType, result.workspace, result.updates().map { cacheOne(it) })
-
-        return result.workspace.wrapResult(cachedTree, result.taskName, result.taskMeta)
+            override fun get(name: Name): TaskData<T>? = result[name]?.let { evaluateDatum(it) }
+        }
     }
 }
 

dataforge-workspace/src/jvmMain/kotlin/space/kscience/dataforge/workspace/InMemoryWorkspaceCache.kt

@@ -1,39 +1,39 @@
 package space.kscience.dataforge.workspace
 
-import kotlinx.coroutines.flow.map
-import space.kscience.dataforge.data.*
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.names.Name
 import kotlin.reflect.KType
 import kotlin.reflect.full.isSubtypeOf
 
-private data class TaskResultId(val name: Name, val meta: Meta)
+private typealias TaskResultId = Pair<Name, Meta>
 
 
 public class InMemoryWorkspaceCache : WorkspaceCache {
 
-    private val cache = HashMap<TaskResultId, HashMap<Name, Data<*>>>()
+    // never do that at home!
+    private val cache = HashMap<TaskResultId, HashMap<Name, TaskData<*>>>()
 
     @Suppress("UNCHECKED_CAST")
-    private fun <T> Data<*>.checkType(taskType: KType): Data<T> =
-        if (type.isSubtypeOf(taskType)) this as Data<T>
+    private fun <T : Any> TaskData<*>.checkType(taskType: KType): TaskData<T> =
+        if (type.isSubtypeOf(taskType)) this as TaskData<T>
         else error("Cached data type mismatch: expected $taskType but got $type")
 
-    override suspend fun <T> cache(result: TaskResult<T>): TaskResult<T> {
-        fun cacheOne(data: NamedData<T>): NamedData<T> {
-            val cachedData =  cache.getOrPut(TaskResultId(result.taskName, result.taskMeta)){
-                HashMap()
-            }.getOrPut(data.name){
-                data.data
-            }
-            return cachedData.checkType<T>(result.dataType).named(data.name)
+    override suspend fun <T : Any> evaluate(result: TaskResult<T>): TaskResult<T> {
+        for (d: TaskData<T> in result) {
+            cache.getOrPut(result.taskName to result.taskMeta) { HashMap() }.getOrPut(d.name) { d }
         }
 
+        return object : TaskResult<T> by result {
+            override fun iterator(): Iterator<TaskData<T>> = (cache[result.taskName to result.taskMeta]
+                ?.values?.map { it.checkType<T>(result.dataType) }
+                ?: emptyList()).iterator()
 
-        val cachedTree = result.asSequence().map { cacheOne(it) }
-            .toObservableTree(result.dataType, result.workspace, result.updates().map { cacheOne(it) })
-
-        return result.workspace.wrapResult(cachedTree, result.taskName, result.taskMeta)
+            override fun get(name: Name): TaskData<T>? {
+                val cached: TaskData<*> = cache[result.taskName to result.taskMeta]?.get(name) ?: return null
+                //TODO check types
+                return cached.checkType(result.dataType)
+            }
+        }
     }
 }
 

dataforge-workspace/src/jvmMain/kotlin/space/kscience/dataforge/workspace/fileData.kt

@@ -0,0 +1,318 @@
+package space.kscience.dataforge.workspace
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import space.kscience.dataforge.context.error
+import space.kscience.dataforge.context.logger
+import space.kscience.dataforge.context.warn
+import space.kscience.dataforge.data.*
+import space.kscience.dataforge.io.*
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.meta.copy
+import space.kscience.dataforge.meta.string
+import space.kscience.dataforge.misc.DFExperimental
+import space.kscience.dataforge.misc.DFInternal
+import space.kscience.dataforge.names.Name
+import space.kscience.dataforge.names.NameToken
+import space.kscience.dataforge.names.asName
+import space.kscience.dataforge.names.plus
+import space.kscience.dataforge.workspace.FileData.Companion.DEFAULT_IGNORE_EXTENSIONS
+import java.nio.file.Files
+import java.nio.file.Path
+import java.nio.file.StandardWatchEventKinds
+import java.nio.file.WatchEvent
+import java.nio.file.attribute.BasicFileAttributes
+import java.nio.file.spi.FileSystemProvider
+import java.time.Instant
+import kotlin.io.path.*
+import kotlin.reflect.KType
+import kotlin.reflect.typeOf
+
+
+//public typealias FileFormatResolver<T> = (Path, Meta) -> IOFormat<T>
+
+public typealias FileFormatResolver<T> = (path: Path, meta: Meta) -> IOReader<T>?
+
+/**
+ * A data based on a filesystem [Path]
+ */
+public class FileData<T> internal constructor(private val data: Data<T>, public val path: Path) : Data<T> by data {
+
+    //    public val path: String? get() = meta[META_FILE_PATH_KEY].string
+//    public val extension: String? get() = meta[META_FILE_EXTENSION_KEY].string
+//
+    public val createdTime: Instant? get() = meta[FILE_CREATE_TIME_KEY].string?.let { Instant.parse(it) }
+    public val updatedTime: Instant? get() = meta[FILE_UPDATE_TIME_KEY].string?.let { Instant.parse(it) }
+
+    public companion object {
+        public val FILE_KEY: Name = "file".asName()
+        public val FILE_PATH_KEY: Name = FILE_KEY + "path"
+        public val FILE_EXTENSION_KEY: Name = FILE_KEY + "extension"
+        public val FILE_CREATE_TIME_KEY: Name = FILE_KEY + "created"
+        public val FILE_UPDATE_TIME_KEY: Name = FILE_KEY + "updated"
+        public const val DF_FILE_EXTENSION: String = "df"
+        public val DEFAULT_IGNORE_EXTENSIONS: Set<String> = setOf(DF_FILE_EXTENSION)
+    }
+}
+
+
+/**
+ * Read data with supported envelope format and binary format. If envelope format is null, then read binary directly from file.
+ * The operation is blocking since it must read meta header. The reading of envelope body is lazy
+ */
+@OptIn(DFInternal::class)
+@DFExperimental
+public fun <T : Any> IOPlugin.readDataFile(
+    path: Path,
+    formatResolver: FileFormatResolver<T>,
+): FileData<T>? {
+    val envelope = readEnvelopeFile(path, true)
+    val format = formatResolver(path, envelope.meta) ?: return null
+    val updatedMeta = envelope.meta.copy {
+        FileData.FILE_PATH_KEY put path.toString()
+        FileData.FILE_EXTENSION_KEY put path.extension
+
+        val attributes = path.readAttributes<BasicFileAttributes>()
+        FileData.FILE_UPDATE_TIME_KEY put attributes.lastModifiedTime().toInstant().toString()
+        FileData.FILE_CREATE_TIME_KEY put attributes.creationTime().toInstant().toString()
+    }
+    return FileData(
+        Data(format.type, updatedMeta) {
+            (envelope.data ?: Binary.EMPTY).readWith(format)
+        },
+        path
+    )
+}
+
+
+context(IOPlugin) @DFExperimental
+public fun <T : Any> DataSetBuilder<T>.directory(
+    path: Path,
+    ignoreExtensions: Set<String>,
+    formatResolver: FileFormatResolver<T>,
+) {
+    Files.list(path).forEach { childPath ->
+        val fileName = childPath.fileName.toString()
+        if (fileName.startsWith(IOPlugin.META_FILE_NAME)) {
+            meta(readMetaFile(childPath))
+        } else if (!fileName.startsWith("@")) {
+            file(childPath, ignoreExtensions, formatResolver)
+        }
+    }
+}
+
+/**
+ * Read the directory as a data node. If [path] is a zip archive, read it as directory
+ */
+@DFExperimental
+@DFInternal
+public fun <T : Any> IOPlugin.readDataDirectory(
+    type: KType,
+    path: Path,
+    ignoreExtensions: Set<String> = DEFAULT_IGNORE_EXTENSIONS,
+    formatResolver: FileFormatResolver<T>,
+): DataTree<T> {
+    //read zipped data node
+    if (path.fileName != null && path.fileName.toString().endsWith(".zip")) {
+        //Using explicit Zip file system to avoid bizarre compatibility bugs
+        val fsProvider = FileSystemProvider.installedProviders().find { it.scheme == "jar" }
+            ?: error("Zip file system provider not found")
+        val fs = fsProvider.newFileSystem(path, mapOf("create" to "true"))
+
+        return readDataDirectory(type, fs.rootDirectories.first(), ignoreExtensions, formatResolver)
+    }
+    if (!Files.isDirectory(path)) error("Provided path $path is not a directory")
+    return DataTree(type) {
+        meta {
+            FileData.FILE_PATH_KEY put path.toString()
+        }
+        directory(path, ignoreExtensions, formatResolver)
+    }
+}
+
+@OptIn(DFInternal::class)
+@DFExperimental
+public inline fun <reified T : Any> IOPlugin.readDataDirectory(
+    path: Path,
+    ignoreExtensions: Set<String> = DEFAULT_IGNORE_EXTENSIONS,
+    noinline formatResolver: FileFormatResolver<T>,
+): DataTree<T> = readDataDirectory(typeOf<T>(), path, ignoreExtensions, formatResolver)
+
+/**
+ * Read a raw binary data tree from the directory. All files are read as-is (save for meta files).
+ */
+@DFExperimental
+public fun IOPlugin.readRawDirectory(
+    path: Path,
+    ignoreExtensions: Set<String> = emptySet(),
+): DataTree<Binary> = readDataDirectory(path, ignoreExtensions) { _, _ -> IOReader.binary }
+
+
+private fun Path.toName() = Name(map { NameToken.parse(it.nameWithoutExtension) })
+
+@DFInternal
+@DFExperimental
+public fun <T : Any> IOPlugin.monitorDataDirectory(
+    type: KType,
+    path: Path,
+    ignoreExtensions: Set<String> = DEFAULT_IGNORE_EXTENSIONS,
+    formatResolver: FileFormatResolver<T>,
+): DataSource<T> {
+    if (path.fileName.toString().endsWith(".zip")) error("Monitoring not supported for ZipFS")
+    if (!Files.isDirectory(path)) error("Provided path $path is not a directory")
+    return DataSource(type, context) {
+        directory(path, ignoreExtensions, formatResolver)
+        launch(Dispatchers.IO) {
+            val watchService = path.fileSystem.newWatchService()
+
+            path.register(
+                watchService,
+                StandardWatchEventKinds.ENTRY_DELETE,
+                StandardWatchEventKinds.ENTRY_MODIFY,
+                StandardWatchEventKinds.ENTRY_CREATE
+            )
+
+            do {
+                val key = watchService.take()
+                if (key != null) {
+                    for (event: WatchEvent<*> in key.pollEvents()) {
+                        val eventPath = event.context() as Path
+                        if (event.kind() == StandardWatchEventKinds.ENTRY_DELETE) {
+                            remove(eventPath.toName())
+                        } else {
+                            val fileName = eventPath.fileName.toString()
+                            if (fileName.startsWith(IOPlugin.META_FILE_NAME)) {
+                                meta(readMetaFile(eventPath))
+                            } else if (!fileName.startsWith("@")) {
+                                file(eventPath, ignoreExtensions, formatResolver)
+                            }
+                        }
+                    }
+                    key.reset()
+                }
+            } while (isActive && key != null)
+        }
+    }
+}
+
+
+/**
+ * Start monitoring given directory ([path]) as a [DataSource].
+ */
+@OptIn(DFInternal::class)
+@DFExperimental
+public inline fun <reified T : Any> IOPlugin.monitorDataDirectory(
+    path: Path,
+    ignoreExtensions: Set<String> = DEFAULT_IGNORE_EXTENSIONS,
+    noinline formatResolver: FileFormatResolver<T>,
+): DataSource<T> = monitorDataDirectory(typeOf<T>(), path, ignoreExtensions, formatResolver)
+
+/**
+ * Read and monitor raw binary data tree from the directory. All files are read as-is (save for meta files).
+ */
+@DFExperimental
+public fun IOPlugin.monitorRawDirectory(
+    path: Path,
+    ignoreExtensions: Set<String> = DEFAULT_IGNORE_EXTENSIONS,
+): DataSource<Binary> = monitorDataDirectory(path, ignoreExtensions) { _, _ -> IOReader.binary }
+
+/**
+ * Write data tree to existing directory or create a new one using default [java.nio.file.FileSystem] provider
+ */
+@DFExperimental
+public suspend fun <T : Any> IOPlugin.writeDataDirectory(
+    path: Path,
+    tree: DataTree<T>,
+    format: IOWriter<T>,
+    envelopeFormat: EnvelopeFormat? = null,
+) {
+    withContext(Dispatchers.IO) {
+        if (!Files.exists(path)) {
+            Files.createDirectories(path)
+        } else if (!Files.isDirectory(path)) {
+            error("Can't write a node into file")
+        }
+        tree.items.forEach { (token, item) ->
+            val childPath = path.resolve(token.toString())
+            when (item) {
+                is DataTreeItem.Node -> {
+                    writeDataDirectory(childPath, item.tree, format, envelopeFormat)
+                }
+
+                is DataTreeItem.Leaf -> {
+                    val envelope = item.data.toEnvelope(format)
+                    if (envelopeFormat != null) {
+                        writeEnvelopeFile(childPath, envelope, envelopeFormat)
+                    } else {
+                        writeEnvelopeDirectory(childPath, envelope)
+                    }
+                }
+            }
+        }
+        val treeMeta = tree.meta
+        writeMetaFile(path, treeMeta)
+    }
+}
+
+/**
+ * Reads the specified resources and returns a [DataTree] containing the data.
+ *
+ * @param resources The names of the resources to read.
+ * @param classLoader The class loader to use for loading the resources. By default, it uses the current thread's context class loader.
+ * @return A DataTree containing the data read from the resources.
+ */
+@DFExperimental
+private fun IOPlugin.readResources(
+    vararg resources: String,
+    classLoader: ClassLoader = Thread.currentThread().contextClassLoader,
+): DataTree<Binary> {
+//    require(resource.isNotBlank()) {"Can't mount root resource tree as data root"}
+    return DataTree {
+        resources.forEach { resource ->
+            val path = classLoader.getResource(resource)?.toURI()?.toPath() ?: error(
+                "Resource with name $resource is not resolved"
+            )
+            node(resource, readRawDirectory(path))
+        }
+    }
+}
+
+/**
+ * Add file/directory-based data tree item
+ *
+ * @param ignoreExtensions a list of file extensions for which extension should be cut from the resulting item name
+ */
+context(IOPlugin)
+@OptIn(DFInternal::class)
+@DFExperimental
+public fun <T : Any> DataSetBuilder<T>.file(
+    path: Path,
+    ignoreExtensions: Set<String> = DEFAULT_IGNORE_EXTENSIONS,
+    formatResolver: FileFormatResolver<out T>,
+) {
+
+    fun defaultPath() = if (path.extension in ignoreExtensions) path.nameWithoutExtension else path.name
+
+    try {
+        //If path is a single file or a special directory, read it as single datum
+        if (!Files.isDirectory(path) || Files.list(path).allMatch { it.fileName.toString().startsWith("@") }) {
+            val data = readDataFile(path, formatResolver)
+            if (data == null) {
+                logger.warn { "File format is not resolved for $path. Skipping." }
+                return
+            }
+            val name: String = data.meta[Envelope.ENVELOPE_NAME_KEY].string ?: defaultPath()
+            data(name.asName(), data)
+        } else {
+            //otherwise, read as directory
+            val data: DataTree<T> = readDataDirectory(dataType, path, ignoreExtensions, formatResolver)
+            val name = data.meta[Envelope.ENVELOPE_NAME_KEY].string ?: defaultPath()
+            node(name.asName(), data)
+        }
+    } catch (ex: Exception) {
+        logger.error { "Failed to read file or directory at $path: ${ex.message}" }
+    }
+}
+

dataforge-workspace/src/jvmMain/kotlin/space/kscience/dataforge/workspace/readFileData.kt

@@ -1,186 +0,0 @@
-package space.kscience.dataforge.workspace
-
-import kotlinx.coroutines.*
-import space.kscience.dataforge.data.Data
-import space.kscience.dataforge.data.DataSink
-import space.kscience.dataforge.data.StaticData
-import space.kscience.dataforge.io.*
-import space.kscience.dataforge.meta.Meta
-import space.kscience.dataforge.meta.copy
-import space.kscience.dataforge.misc.DFExperimental
-import space.kscience.dataforge.misc.DFInternal
-import space.kscience.dataforge.names.Name
-import space.kscience.dataforge.names.NameToken
-import space.kscience.dataforge.names.asName
-import space.kscience.dataforge.names.plus
-import java.nio.file.Files
-import java.nio.file.Path
-import java.nio.file.StandardWatchEventKinds
-import java.nio.file.WatchEvent
-import java.nio.file.attribute.BasicFileAttributes
-import java.nio.file.spi.FileSystemProvider
-import kotlin.io.path.*
-import kotlin.reflect.typeOf
-
-
-public object FileData {
-    public val FILE_KEY: Name = "file".asName()
-    public val FILE_PATH_KEY: Name = FILE_KEY + "path"
-    public val FILE_EXTENSION_KEY: Name = FILE_KEY + "extension"
-    public val FILE_CREATE_TIME_KEY: Name = FILE_KEY + "created"
-    public val FILE_UPDATE_TIME_KEY: Name = FILE_KEY + "updated"
-    public const val DF_FILE_EXTENSION: String = "df"
-    public val DEFAULT_IGNORE_EXTENSIONS: Set<String> = setOf(DF_FILE_EXTENSION)
-
-}
-
-
-/**
- * Read data with supported envelope format and binary format. If the envelope format is null, then read binary directly from file.
- * The operation is blocking since it must read the meta header. The reading of envelope body is lazy
- */
-@OptIn(DFExperimental::class)
-public fun IOPlugin.readFileData(
-    path: Path,
-): Data<Binary> {
-    val envelope = readEnvelopeFile(path, true)
-    val updatedMeta = envelope.meta.copy {
-        FileData.FILE_PATH_KEY put path.toString()
-        FileData.FILE_EXTENSION_KEY put path.extension
-
-        val attributes = path.readAttributes<BasicFileAttributes>()
-        FileData.FILE_UPDATE_TIME_KEY put attributes.lastModifiedTime().toInstant().toString()
-        FileData.FILE_CREATE_TIME_KEY put attributes.creationTime().toInstant().toString()
-    }
-    return StaticData(
-        typeOf<Binary>(),
-        envelope.data ?: Binary.EMPTY,
-        updatedMeta
-    )
-}
-
-public fun DataSink<Binary>.file(io: IOPlugin, name: Name, path: Path) {
-    if (!path.isRegularFile()) error("Only regular files could be handled by this function")
-    put(name, io.readFileData(path))
-}
-
-public fun DataSink<Binary>.directory(
-    io: IOPlugin,
-    name: Name,
-    path: Path,
-) {
-    if (!path.isDirectory()) error("Only directories could be handled by this function")
-    //process root data
-
-    var dataBinary: Binary? = null
-    var meta: Meta? = null
-    Files.list(path).forEach { childPath ->
-        val fileName = childPath.fileName.toString()
-        if (fileName == IOPlugin.DATA_FILE_NAME) {
-            dataBinary = childPath.asBinary()
-        } else if (fileName.startsWith(IOPlugin.META_FILE_NAME)) {
-            meta = io.readMetaFileOrNull(childPath)
-        } else if (!fileName.startsWith("@")) {
-            val token = if (childPath.isRegularFile() && childPath.extension in FileData.DEFAULT_IGNORE_EXTENSIONS) {
-                NameToken(childPath.nameWithoutExtension)
-            } else {
-                NameToken(childPath.name)
-            }
-
-            files(io, name + token, childPath)
-        }
-    }
-
-    //set data if it is relevant
-    if (dataBinary != null || meta != null) {
-        put(
-            name,
-            StaticData(
-                typeOf<Binary>(),
-                dataBinary ?: Binary.EMPTY,
-                meta ?: Meta.EMPTY
-            )
-        )
-    }
-}
-
-public fun DataSink<Binary>.files(
-    io: IOPlugin,
-    name: Name,
-    path: Path,
-) {
-    if (path.isRegularFile() && path.extension == "zip") {
-        //Using explicit Zip file system to avoid bizarre compatibility bugs
-        val fsProvider = FileSystemProvider.installedProviders().find { it.scheme == "jar" }
-            ?: error("Zip file system provider not found")
-        val fs = fsProvider.newFileSystem(path, emptyMap<String, Any>())
-
-        files(io, name, fs.rootDirectories.first())
-    }
-    if (path.isRegularFile()) {
-        file(io, name, path)
-    } else {
-        directory(io, name, path)
-    }
-}
-
-
-private fun Path.toName() = Name(map { NameToken.parse(it.nameWithoutExtension) })
-
-@DFInternal
-@DFExperimental
-public fun DataSink<Binary>.monitorFiles(
-    io: IOPlugin,
-    name: Name,
-    path: Path,
-    scope: CoroutineScope = io.context,
-): Job {
-    files(io, name, path)
-    return scope.launch(Dispatchers.IO) {
-        val watchService = path.fileSystem.newWatchService()
-
-        path.register(
-            watchService,
-            StandardWatchEventKinds.ENTRY_DELETE,
-            StandardWatchEventKinds.ENTRY_MODIFY,
-            StandardWatchEventKinds.ENTRY_CREATE
-        )
-
-        do {
-            val key = watchService.take()
-            if (key != null) {
-                for (event: WatchEvent<*> in key.pollEvents()) {
-                    val eventPath = event.context() as Path
-                    if (event.kind() == StandardWatchEventKinds.ENTRY_DELETE) {
-                        put(eventPath.toName(), null)
-                    } else {
-                        val fileName = eventPath.fileName.toString()
-                        if (!fileName.startsWith("@")) {
-                            files(io, name, eventPath)
-                        }
-                    }
-                }
-                key.reset()
-            }
-        } while (isActive && key != null)
-    }
-
-}
-
-/**
- * @param resources The names of the resources to read.
- * @param classLoader The class loader to use for loading the resources. By default, it uses the current thread's context class loader.
- */
-@DFExperimental
-public fun DataSink<Binary>.resources(
-    io: IOPlugin,
-    vararg resources: String,
-    classLoader: ClassLoader = Thread.currentThread().contextClassLoader,
-) {
-    resources.forEach { resource ->
-        val path = classLoader.getResource(resource)?.toURI()?.toPath() ?: error(
-            "Resource with name $resource is not resolved"
-        )
-        files(io, resource.asName(), path)
-    }
-}

dataforge-workspace/src/jvmMain/kotlin/space/kscience/dataforge/workspace/workspaceJvm.kt

@@ -1,6 +1,6 @@
 package space.kscience.dataforge.workspace
 
-import space.kscience.dataforge.data.DataTree
+import space.kscience.dataforge.data.DataSet
 import space.kscience.dataforge.data.filterByType
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.misc.DFExperimental
@@ -16,13 +16,14 @@ import space.kscience.dataforge.names.matches
  */
 @OptIn(DFExperimental::class)
 public inline fun <reified T : Any> TaskResultBuilder<*>.dataByType(namePattern: Name? = null): DataSelector<T> =
-    DataSelector<T> { workspace, _ ->
-        workspace.data.filterByType { name, _, _ ->
-            namePattern == null || name.matches(namePattern)
-        }
+    object : DataSelector<T> {
+        override suspend fun select(workspace: Workspace, meta: Meta): DataSet<T> =
+            workspace.data.filterByType { name, _ ->
+                namePattern == null || name.matches(namePattern)
+            }
     }
 
 public suspend inline fun <reified T : Any> TaskResultBuilder<*>.fromTask(
     task: Name,
     taskMeta: Meta = Meta.EMPTY,
-): DataTree<T> = workspace.produce(task, taskMeta).filterByType()
+): DataSet<T> = workspace.produce(task, taskMeta).filterByType()

dataforge-workspace/src/jvmMain/kotlin/space/kscience/dataforge/workspace/writeFileData.kt

@@ -1,72 +0,0 @@
-package space.kscience.dataforge.workspace
-
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.withContext
-import space.kscience.dataforge.data.*
-import space.kscience.dataforge.io.*
-import space.kscience.dataforge.misc.DFExperimental
-import space.kscience.dataforge.names.Name
-import java.nio.file.Files
-import java.nio.file.Path
-import java.nio.file.spi.FileSystemProvider
-import kotlin.io.path.Path
-import kotlin.io.path.createDirectories
-import kotlin.io.path.exists
-import kotlin.io.path.extension
-
-
-/**
- * Write the data tree to existing directory or create a new one using default [java.nio.file.FileSystem] provider
- *
- * @param nameToPath a [Name] to [Path] converter used to create
- */
-@DFExperimental
-public suspend fun <T : Any> IOPlugin.writeDataDirectory(
-    path: Path,
-    dataSet: DataTree<T>,
-    format: IOWriter<T>,
-    envelopeFormat: EnvelopeFormat? = null,
-): Unit = withContext(Dispatchers.IO) {
-    if (!Files.exists(path)) {
-        Files.createDirectories(path)
-    } else if (!Files.isDirectory(path)) {
-        error("Can't write a node into file")
-    }
-    dataSet.forEach { (name, data) ->
-        val childPath = path.resolve(name.tokens.joinToString("/") { token -> token.toStringUnescaped() })
-        childPath.parent.createDirectories()
-        val envelope = data.toEnvelope(format)
-        if (envelopeFormat != null) {
-            writeEnvelopeFile(childPath, envelope, envelopeFormat)
-        } else {
-            writeEnvelopeDirectory(childPath, envelope)
-        }
-    }
-    dataSet.meta?.let { writeMetaFile(path, it) }
-
-}
-
-/**
- * Write this [DataTree] as a zip archive
- */
-@DFExperimental
-public suspend fun <T : Any> IOPlugin.writeZip(
-    path: Path,
-    dataSet: DataTree<T>,
-    format: IOWriter<T>,
-    envelopeFormat: EnvelopeFormat? = null,
-): Unit = withContext(Dispatchers.IO) {
-    if (path.exists()) error("Can't override existing zip data file $path")
-    val actualFile = if (path.extension == "zip") {
-        path
-    } else {
-        path.resolveSibling(path.fileName.toString() + ".zip")
-    }
-    val fsProvider = FileSystemProvider.installedProviders().find { it.scheme == "jar" }
-        ?: error("Zip file system provider not found")
-    //val fs = FileSystems.newFileSystem(actualFile, mapOf("create" to true))
-    val fs = fsProvider.newFileSystem(actualFile, mapOf("create" to true))
-    fs.use {
-        writeDataDirectory(fs.rootDirectories.first(), dataSet, format, envelopeFormat)
-    }
-}

dataforge-workspace/src/jvmMain/kotlin/space/kscience/dataforge/workspace/zipData.kt

@@ -0,0 +1,73 @@
+package space.kscience.dataforge.workspace
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import space.kscience.dataforge.data.DataTree
+import space.kscience.dataforge.data.DataTreeItem
+import space.kscience.dataforge.io.*
+import space.kscience.dataforge.misc.DFExperimental
+import java.nio.file.Files
+import java.nio.file.Path
+import java.nio.file.StandardOpenOption
+import java.util.zip.ZipEntry
+import java.util.zip.ZipOutputStream
+
+
+private suspend fun <T : Any> ZipOutputStream.writeNode(
+    name: String,
+    treeItem: DataTreeItem<T>,
+    dataFormat: IOFormat<T>,
+    envelopeFormat: EnvelopeFormat = TaggedEnvelopeFormat,
+): Unit = withContext(Dispatchers.IO) {
+    when (treeItem) {
+        is DataTreeItem.Leaf -> {
+            //TODO add directory-based envelope writer
+            val envelope = treeItem.data.toEnvelope(dataFormat)
+            val entry = ZipEntry(name)
+            putNextEntry(entry)
+
+            //TODO remove additional copy
+            val bytes = ByteArray {
+                writeWith(envelopeFormat, envelope)
+            }
+            write(bytes)
+
+        }
+
+        is DataTreeItem.Node -> {
+            val entry = ZipEntry("$name/")
+            putNextEntry(entry)
+            closeEntry()
+            treeItem.tree.items.forEach { (token, item) ->
+                val childName = "$name/$token"
+                writeNode(childName, item, dataFormat, envelopeFormat)
+            }
+        }
+    }
+}
+
+/**
+ * Write this [DataTree] as a zip archive
+ */
+@DFExperimental
+public suspend fun <T : Any> DataTree<T>.writeZip(
+    path: Path,
+    format: IOFormat<T>,
+    envelopeFormat: EnvelopeFormat = TaggedEnvelopeFormat,
+): Unit = withContext(Dispatchers.IO) {
+    val actualFile = if (path.toString().endsWith(".zip")) {
+        path
+    } else {
+        path.resolveSibling(path.fileName.toString() + ".zip")
+    }
+    val fos = Files.newOutputStream(
+        actualFile,
+        StandardOpenOption.WRITE,
+        StandardOpenOption.CREATE,
+        StandardOpenOption.TRUNCATE_EXISTING
+    )
+    val zos = ZipOutputStream(fos)
+    zos.use {
+        it.writeNode("", DataTreeItem.Node(this@writeZip), format, envelopeFormat)
+    }
+}

dataforge-workspace/src/jvmTest/kotlin/space/kscience/dataforge/workspace/CachingWorkspaceTest.kt

@@ -1,16 +1,18 @@
 package space.kscience.dataforge.workspace
 
+import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.test.runTest
 import org.junit.jupiter.api.Test
-import space.kscience.dataforge.data.wrap
+import space.kscience.dataforge.data.startAll
+import space.kscience.dataforge.data.static
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.meta.boolean
 import space.kscience.dataforge.meta.get
 import space.kscience.dataforge.misc.DFExperimental
 import kotlin.test.assertEquals
 
-@OptIn(DFExperimental::class)
+@OptIn(ExperimentalCoroutinesApi::class, DFExperimental::class)
 internal class CachingWorkspaceTest {
 
     @Test
@@ -22,7 +24,7 @@ internal class CachingWorkspaceTest {
             data {
                 //statically initialize data
                 repeat(5) {
-                    wrap("myData[$it]", it)
+                    static("myData[$it]", it)
                 }
             }
 
@@ -35,10 +37,11 @@ internal class CachingWorkspaceTest {
                 }
             }
 
+            @Suppress("UNUSED_VARIABLE")
             val doSecond by task<Any> {
                 transformEach(
                     doFirst,
-                    dependencyMeta = if (taskMeta["flag"].boolean == true) taskMeta else Meta.EMPTY
+                    dependencyMeta = if(taskMeta["flag"].boolean == true) taskMeta else Meta.EMPTY
                 ) { _, name, _ ->
                     secondCounter++
                     println("Done second on $name with flag=${taskMeta["flag"].boolean ?: false}")
@@ -50,15 +53,13 @@ internal class CachingWorkspaceTest {
         val secondA = workspace.produce("doSecond")
         val secondB = workspace.produce("doSecond", Meta { "flag" put true })
         val secondC = workspace.produce("doSecond")
-        //use coroutineScope to wait for the result
         coroutineScope {
-            first.launch(this)
-            secondA.launch(this)
-            secondB.launch(this)
+            first.startAll(this)
+            secondA.startAll(this)
+            secondB.startAll(this)
             //repeat to check caching
-            secondC.launch(this)
+            secondC.startAll(this)
         }
-
         assertEquals(10, firstCounter)
         assertEquals(10, secondCounter)
     }

dataforge-workspace/src/jvmTest/kotlin/space/kscience/dataforge/workspace/DataPropagationTest.kt

@@ -20,13 +20,13 @@ class DataPropagationTestPlugin : WorkspacePlugin() {
         val result: Data<Int> = selectedData.foldToData(0) { result, data ->
             result + data.value
         }
-        put("result", result)
+        data("result", result)
     }
 
 
     val singleData by task<Int> {
         workspace.data.filterByType<Int>()["myData[12]"]?.let {
-            put("result", it)
+            data("result", it)
         }
     }
 
@@ -47,7 +47,7 @@ class DataPropagationTest {
         }
         data {
             repeat(100) {
-                wrap("myData[$it]", it)
+                static("myData[$it]", it)
             }
         }
     }
@@ -55,12 +55,12 @@ class DataPropagationTest {
     @Test
     fun testAllData() = runTest {
         val node = testWorkspace.produce("Test.allData")
-        assertEquals(4950, node.content.asSequence().single().await())
+        assertEquals(4950, node.asSequence().single().await())
     }
 
     @Test
     fun testSingleData() = runTest {
         val node = testWorkspace.produce("Test.singleData")
-        assertEquals(12, node.content.asSequence().single().await())
+        assertEquals(12, node.asSequence().single().await())
     }
 }

dataforge-workspace/src/jvmTest/kotlin/space/kscience/dataforge/workspace/FileDataTest.kt

@@ -1,5 +1,6 @@
 package space.kscience.dataforge.workspace
 
+import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.test.runTest
 import kotlinx.io.Sink
 import kotlinx.io.Source
@@ -8,34 +9,38 @@ import kotlinx.io.writeString
 import space.kscience.dataforge.context.Context
 import space.kscience.dataforge.context.Global
 import space.kscience.dataforge.data.*
-import space.kscience.dataforge.io.*
+import space.kscience.dataforge.io.Envelope
+import space.kscience.dataforge.io.IOFormat
+import space.kscience.dataforge.io.io
+import space.kscience.dataforge.io.readEnvelopeFile
 import space.kscience.dataforge.io.yaml.YamlPlugin
 import space.kscience.dataforge.meta.get
 import space.kscience.dataforge.misc.DFExperimental
-import space.kscience.dataforge.names.Name
 import java.nio.file.Files
-import kotlin.io.path.deleteExisting
 import kotlin.io.path.fileSize
 import kotlin.io.path.toPath
+import kotlin.reflect.KType
+import kotlin.reflect.typeOf
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
 
 class FileDataTest {
     val dataNode = DataTree<String> {
-        branch("dir") {
-            wrap("a", "Some string") {
+        node("dir") {
+            static("a", "Some string") {
                 "content" put "Some string"
             }
         }
-        wrap("b", "root data")
-//        meta {
-//            "content" put "This is root meta node"
-//        }
+        static("b", "root data")
+        meta {
+            "content" put "This is root meta node"
+        }
     }
 
 
     object StringIOFormat : IOFormat<String> {
+        override val type: KType get() = typeOf<String>()
 
         override fun writeTo(sink: Sink, obj: String) {
             sink.writeString(obj)
@@ -46,33 +51,29 @@ class FileDataTest {
 
     @Test
     @DFExperimental
-    fun testDataWriteRead() = runTest {
-        val io = Global.io
+    fun testDataWriteRead() = with(Global.io) {
         val dir = Files.createTempDirectory("df_data_node")
-        io.writeDataDirectory(dir, dataNode, StringIOFormat)
-        println(dir.toUri().toString())
-        val data = DataTree {
-            files(io, Name.EMPTY, dir)
+        runBlocking {
+            writeDataDirectory(dir, dataNode, StringIOFormat)
+            println(dir.toUri().toString())
+            val reconstructed = readDataDirectory(dir) { _, _ -> StringIOFormat }
+            assertEquals(dataNode["dir.a"]?.meta?.get("content"), reconstructed["dir.a"]?.meta?.get("content"))
+            assertEquals(dataNode["b"]?.await(), reconstructed["b"]?.await())
         }
-        val reconstructed = data.transform { (_, value) -> value.toByteArray().decodeToString() }
-        assertEquals(dataNode["dir.a"]?.meta?.get("content"), reconstructed["dir.a"]?.meta?.get("content"))
-        assertEquals(dataNode["b"]?.await(), reconstructed["b"]?.await())
     }
 
 
     @Test
     @DFExperimental
     fun testZipWriteRead() = runTest {
-        val io = Global.io
-        val zip = Files.createTempFile("df_data_node", ".zip")
-        zip.deleteExisting()
-        io.writeZip(zip, dataNode, StringIOFormat)
-        println(zip.toUri().toString())
-        val reconstructed = DataTree { files(io, Name.EMPTY, zip) }
-            .transform { (_, value) -> value.toByteArray().decodeToString() }
-        assertEquals(dataNode["dir.a"]?.meta?.get("content"), reconstructed["dir.a"]?.meta?.get("content"))
-        assertEquals(dataNode["b"]?.await(), reconstructed["b"]?.await())
-
+        with(Global.io) {
+            val zip = Files.createTempFile("df_data_node", ".zip")
+            dataNode.writeZip(zip, StringIOFormat)
+            println(zip.toUri().toString())
+            val reconstructed = readDataDirectory(zip) { _, _ -> StringIOFormat }
+            assertEquals(dataNode["dir.a"]?.meta?.get("content"), reconstructed["dir.a"]?.meta?.get("content"))
+            assertEquals(dataNode["b"]?.await(), reconstructed["b"]?.await())
+        }
     }
 
     @OptIn(DFExperimental::class)

dataforge-workspace/src/jvmTest/kotlin/space/kscience/dataforge/workspace/FileWorkspaceCacheTest.kt

@@ -3,7 +3,8 @@ package space.kscience.dataforge.workspace
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.runTest
 import org.junit.jupiter.api.Test
-import space.kscience.dataforge.data.wrap
+import space.kscience.dataforge.data.startAll
+import space.kscience.dataforge.data.static
 import space.kscience.dataforge.misc.DFExperimental
 import java.nio.file.Files
 
@@ -16,17 +17,18 @@ class FileWorkspaceCacheTest {
             data {
                 //statically initialize data
                 repeat(5) {
-                    wrap("myData[$it]", it)
+                    static("myData[$it]", it)
                 }
             }
             fileCache(Files.createTempDirectory("dataforge-temporary-cache"))
 
+            @Suppress("UNUSED_VARIABLE")
             val echo by task<String> {
                 transformEach(dataByType<String>()) { arg, _, _ -> arg }
             }
         }
 
-        workspace.produce("echo").launch(this)
+        workspace.produce("echo").startAll(this)
 
     }
 }

dataforge-workspace/src/jvmTest/kotlin/space/kscience/dataforge/workspace/SimpleWorkspaceTest.kt

@@ -27,8 +27,8 @@ public fun <P : Plugin> P.toFactory(): PluginFactory<P> = object : PluginFactory
     override val tag: PluginTag = this@toFactory.tag
 }
 
-public fun Workspace.produceBlocking(task: String, block: MutableMeta.() -> Unit = {}): DataTree<*> = runBlocking {
-    produce(task, block).content
+public fun Workspace.produceBlocking(task: String, block: MutableMeta.() -> Unit = {}): DataSet<Any> = runBlocking {
+    produce(task, block)
 }
 
 @OptIn(DFExperimental::class)
@@ -62,14 +62,14 @@ internal class SimpleWorkspaceTest {
         data {
             //statically initialize data
             repeat(100) {
-                wrap("myData[$it]", it)
+                static("myData[$it]", it)
             }
         }
 
         val filterOne by task<Int> {
             val name by taskMeta.string { error("Name field not defined") }
-            from(testPluginFactory) { test }[name]?.let { source: Data<Int> ->
-                put(name, source)
+            from(testPluginFactory) { test }.getByType<Int>(name)?.let { source ->
+                data(source.name, source.map { it })
             }
         }
 
@@ -97,7 +97,7 @@ internal class SimpleWorkspaceTest {
                 val newData: Data<Int> = data.combine(linearData[data.name]!!) { l, r ->
                     l + r
                 }
-                put(data.name, newData)
+                data(data.name, newData)
             }
         }
 
@@ -106,23 +106,23 @@ internal class SimpleWorkspaceTest {
             val res = from(square).foldToData(0) { l, r ->
                 l + r.value
             }
-            put("sum", res)
+            data("sum", res)
         }
 
         val averageByGroup by task<Int> {
-            val evenSum = workspace.data.filterByType<Int> { name, _, _ ->
+            val evenSum = workspace.data.filterByType<Int> { name, _ ->
                 name.toString().toInt() % 2 == 0
             }.foldToData(0) { l, r ->
                 l + r.value
             }
 
-            put("even", evenSum)
-            val oddSum = workspace.data.filterByType<Int> { name, _, _ ->
+            data("even", evenSum)
+            val oddSum = workspace.data.filterByType<Int> { name, _ ->
                 name.toString().toInt() % 2 == 1
             }.foldToData(0) { l, r ->
                 l + r.value
             }
-            put("odd", oddSum)
+            data("odd", oddSum)
         }
 
         val delta by task<Int> {
@@ -132,7 +132,7 @@ internal class SimpleWorkspaceTest {
             val res = even.combine(odd) { l, r ->
                 l - r
             }
-            put("res", res)
+            data("res", res)
         }
 
         val customPipe by task<Int> {
@@ -140,7 +140,7 @@ internal class SimpleWorkspaceTest {
                 val meta = data.meta.toMutableMeta().apply {
                     "newValue" put 22
                 }
-                put(data.name + "new", data.transform { (data.meta["value"].int ?: 0) + it })
+                data(data.name + "new", data.map { (data.meta["value"].int ?: 0) + it })
             }
         }
 
@@ -159,7 +159,7 @@ internal class SimpleWorkspaceTest {
     @Timeout(1)
     fun testMetaPropagation() = runTest {
         val node = workspace.produce("sum") { "testFlag" put true }
-        val res = node.single().await()
+        val res = node.asSequence().single().await()
     }
 
     @Test
@@ -170,25 +170,20 @@ internal class SimpleWorkspaceTest {
     }
 
     @Test
-    fun testFullSquare() = runTest {
-        val result = workspace.produce("fullSquare")
-        result.forEach {
-            println(
-                """
-                Name: ${it.name}
-                Meta: ${it.meta}
-                Data: ${it.data.await()}
-            """.trimIndent()
-            )
+    fun testFullSquare() {
+        runBlocking {
+            val node = workspace.produce("fullSquare")
+            println(node.toMeta())
         }
     }
 
     @Test
-    fun testFilter() = runTest {
-        val node = workspace.produce("filterOne") {
-            "name" put "myData[12]"
+    fun testFilter() {
+        runBlocking {
+            val node = workspace.produce("filterOne") {
+                "name" put "myData[12]"
+            }
+            assertEquals(12, node.single().await())
         }
-        assertEquals(12, node.single().await())
     }
-
 }