Basic design for workspaces

dataforge-context/src/commonMain/kotlin/hep/dataforge/context/AbstractPlugin.kt

@@ -1,16 +1,16 @@
 package hep.dataforge.context
 
-import hep.dataforge.meta.EmptyMeta
-import hep.dataforge.meta.Meta
+import hep.dataforge.meta.Config
 import hep.dataforge.names.Name
 
-abstract class AbstractPlugin(override val meta: Meta = EmptyMeta) : Plugin {
-
+abstract class AbstractPlugin : Plugin {
     private var _context: Context? = null
 
     override val context: Context
         get() = _context ?: error("Plugin $tag is not attached")
 
+    override val config = Config()
+
     override fun attach(context: Context) {
         this._context = context
     }
@@ -19,6 +19,8 @@ abstract class AbstractPlugin(override val meta: Meta = EmptyMeta) : Plugin {
         this._context = null
     }
 
+    //TODO make configuration activation-safe
+
     override fun provideTop(target: String, name: Name): Any? = null
 
     override fun listTop(target: String): Sequence<Name> = emptySequence()

dataforge-context/src/commonMain/kotlin/hep/dataforge/context/Context.kt

@@ -4,12 +4,14 @@ import hep.dataforge.meta.*
 import hep.dataforge.names.Name
 import hep.dataforge.names.toName
 import hep.dataforge.provider.Provider
+import hep.dataforge.provider.provideAll
 import hep.dataforge.values.Value
 import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
 import mu.KLogger
 import mu.KotlinLogging
 import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+import kotlin.jvm.JvmName
 
 /**
  * The local environment for anything being done in DataForge framework. Contexts are organized into tree structure with [Global] at the top.
@@ -23,29 +25,36 @@ import kotlin.coroutines.CoroutineContext
  * Since plugins could contain mutable state, context has two states: active and inactive. No changes are allowed to active context.
  * @author Alexander Nozik
  */
-interface Context : Named, MetaRepr, Provider, CoroutineScope {
+open class Context(final override val name: String, val parent: Context? = Global) : Named, MetaRepr, Provider,
+    CoroutineScope {
 
-    val parent: Context?
+    private val config = Config()
 
     /**
      * Context properties. Working as substitute for environment variables
      */
-    val properties: Meta
+    val properties: Meta = if (parent == null) {
+        config
+    } else {
+        Laminate(config, parent.properties)
+    }
 
     /**
      * Context logger
      */
-    val logger: KLogger
+    val logger: KLogger = KotlinLogging.logger(name)
 
     /**
      * A [PluginManager] for current context
      */
-    val plugins: PluginManager
+    val plugins: PluginManager by lazy { PluginManager(this) }
+
+    private val activators = HashSet<Any>()
 
     /**
      * Defines if context is used in any kind of active computations. Active context properties and plugins could not be changed
      */
-    val isActive: Boolean
+    val isActive: Boolean = activators.isNotEmpty()
 
     override val defaultTarget: String get() = Plugin.PLUGIN_TARGET
 
@@ -68,20 +77,36 @@ interface Context : Named, MetaRepr, Provider, CoroutineScope {
     /**
      * Mark context as active and used by [activator]
      */
-    fun activate(activator: Any)
+    fun activate(activator: Any) {
+        activators.add(activator)
+    }
 
     /**
      * Mark context unused by [activator]
      */
-    fun deactivate(activator: Any)
+    fun deactivate(activator: Any) {
+        activators.remove(activator)
+    }
+
+    /**
+     * Change the properties of the context. If active, throw an exception
+     */
+    fun configure(action: Config.() -> Unit) {
+        if (isActive) error("Can't configure active context")
+        config.action()
+    }
 
     override val coroutineContext: CoroutineContext
-        get() = Dispatchers.Default
+        get() = EmptyCoroutineContext
 
     /**
      * Detach all plugins and terminate context
      */
-    fun close()
+    open fun close() {
+        if (isActive) error("Can't close active context")
+        //detach all plugins
+        plugins.forEach { it.detach() }
+    }
 
     override fun toMeta(): Meta = buildMeta {
         "parent" to parent?.name
@@ -90,12 +115,45 @@ interface Context : Named, MetaRepr, Provider, CoroutineScope {
     }
 }
 
+/**
+ * A sequences of all objects provided by plugins with given target and type
+ */
+fun Context.members(target: String): Sequence<Any> =
+    plugins.asSequence().flatMap { it.provideAll(target) }
+
+@JvmName("typedMembers")
+inline fun <reified T : Any> Context.members(target: String) =
+    members(target).filterIsInstance<T>()
+
 
 /**
  * A global root context. Closing [Global] terminates the framework.
  */
-expect object Global : Context {
-    fun getContext(name: String): Context
+object Global : Context("GLOBAL", null) {
+    /**
+     * Closing all contexts
+     *
+     * @throws Exception
+     */
+    override fun close() {
+        logger.info { "Shutting down GLOBAL" }
+        for (ctx in contextRegistry.values) {
+            ctx.close()
+        }
+        super.close()
+    }
+
+    private val contextRegistry = HashMap<String, Context>()
+
+    /**
+     * Get previously builder context o builder a new one
+     *
+     * @param name
+     * @return
+     */
+    fun getContext(name: String): Context {
+        return contextRegistry.getOrPut(name) { Context(name) }
+    }
 }
 
 

dataforge-context/src/commonMain/kotlin/hep/dataforge/context/ContextBuilder.kt

@@ -0,0 +1,37 @@
+package hep.dataforge.context
+
+import hep.dataforge.meta.Config
+import hep.dataforge.meta.MetaBuilder
+import hep.dataforge.meta.configure
+
+/**
+ * A convenience builder for context
+ */
+class ContextBuilder(var name: String = "@anonimous", val parent: Context = Global) {
+    private val plugins = ArrayList<Plugin>()
+    private var meta = MetaBuilder()
+
+    fun properties(action: MetaBuilder.() -> Unit) {
+        meta.action()
+    }
+
+    fun plugin(plugin: Plugin) {
+        plugins.add(plugin)
+    }
+
+    fun plugin(tag: PluginTag, action: Config.() -> Unit) {
+        plugins.add(PluginRepository.fetch(tag).configure(action))
+    }
+
+    fun plugin(name: String, group: String = "", version: String = "", action: Config.() -> Unit) {
+        plugin(PluginTag(name, group, version), action)
+    }
+
+    fun build(): Context {
+        return Context(name, parent).apply {
+            this@ContextBuilder.plugins.forEach {
+                plugins.load(it)
+            }
+        }
+    }
+}

dataforge-context/src/commonMain/kotlin/hep/dataforge/context/Plugin.kt

@@ -1,8 +1,8 @@
 package hep.dataforge.context
 
+import hep.dataforge.meta.Configurable
 import hep.dataforge.meta.Meta
 import hep.dataforge.meta.MetaRepr
-import hep.dataforge.meta.Metoid
 import hep.dataforge.meta.buildMeta
 import hep.dataforge.provider.Provider
 
@@ -22,7 +22,7 @@ import hep.dataforge.provider.Provider
  *
  * @author Alexander Nozik
  */
-interface Plugin : Named, Metoid, ContextAware, Provider, MetaRepr {
+interface Plugin : Named, ContextAware, Provider, MetaRepr, Configurable {
 
     /**
      * Get tag for this plugin
@@ -67,7 +67,7 @@ interface Plugin : Named, Metoid, ContextAware, Provider, MetaRepr {
         "context" to context.name
         "type" to this::class.simpleName
         "tag" to tag
-        "meta" to meta
+        "meta" to config
     }
 
     companion object {

dataforge-context/src/commonMain/kotlin/hep/dataforge/context/PluginManager.kt

@@ -1,9 +1,6 @@
 package hep.dataforge.context
 
-import hep.dataforge.meta.EmptyMeta
-import hep.dataforge.meta.Meta
-import hep.dataforge.meta.MetaBuilder
-import hep.dataforge.meta.buildMeta
+import hep.dataforge.meta.*
 import kotlin.reflect.KClass
 
 /**
@@ -115,8 +112,8 @@ class PluginManager(override val context: Context) : ContextAware, Iterable<Plug
     fun load(tag: PluginTag, meta: Meta = EmptyMeta): Plugin {
         val loaded = get(tag, false)
         return when {
-            loaded == null -> load(PluginRepository.fetch(tag, meta))
-            loaded.meta == meta -> loaded // if meta is the same, return existing plugin
+            loaded == null -> load(PluginRepository.fetch(tag)).configure(meta)
+            loaded.config == meta -> loaded // if meta is the same, return existing plugin
             else -> throw RuntimeException("Can't load plugin with tag $tag. Plugin with this tag and different configuration already exists in context.")
         }
     }
@@ -137,7 +134,7 @@ class PluginManager(override val context: Context) : ContextAware, Iterable<Plug
                     error("Corrupt type information in plugin repository")
                 }
             }
-            loaded.meta == meta -> loaded // if meta is the same, return existing plugin
+            loaded.config == meta -> loaded // if meta is the same, return existing plugin
             else -> throw RuntimeException("Can't load plugin with type $type. Plugin with this type and different configuration already exists in context.")
         }
     }

dataforge-context/src/commonMain/kotlin/hep/dataforge/context/PluginRepository.kt

@@ -1,14 +1,17 @@
 package hep.dataforge.context
 
 import hep.dataforge.meta.Meta
+import hep.dataforge.meta.configure
 import kotlin.reflect.KClass
 
 interface PluginFactory {
     val tag: PluginTag
     val type: KClass<out Plugin>
-    fun build(meta: Meta): Plugin
+    fun build(): Plugin
 }
 
+fun PluginFactory.build(meta: Meta) = build().configure(meta)
+
 
 expect object PluginRepository {
 
@@ -24,6 +27,22 @@ expect object PluginRepository {
 /**
  * Fetch specific plugin and instantiate it with given meta
  */
-fun PluginRepository.fetch(tag: PluginTag, meta: Meta): Plugin =
-    PluginRepository.list().find { it.tag.matches(tag) }?.build(meta)
-        ?: error("Plugin with tag $tag not found in the repository")
+fun PluginRepository.fetch(tag: PluginTag): Plugin =
+    PluginRepository.list().find { it.tag.matches(tag) }?.build()
+        ?: error("Plugin with tag $tag not found in the repository")
+
+fun PluginRepository.register(tag: PluginTag, type: KClass<out Plugin>, constructor: () -> Plugin) {
+    val factory = object : PluginFactory {
+        override val tag: PluginTag = tag
+        override val type: KClass<out Plugin> = type
+
+        override fun build(): Plugin = constructor()
+
+    }
+    PluginRepository.register(factory)
+}
+
+inline fun <reified T : Plugin> PluginRepository.register(tag: PluginTag, noinline constructor: () -> T) =
+    register(tag, T::class, constructor)
+
+fun PluginRepository.register(plugin: Plugin) = register(plugin.tag, plugin::class) { plugin }

dataforge-context/src/jsMain/kotlin/hep/dataforge/context/JSContext.kt

@@ -1,75 +0,0 @@
-package hep.dataforge.context
-
-import hep.dataforge.meta.*
-import mu.KLogger
-import mu.KotlinLogging
-import kotlin.jvm.Synchronized
-
-actual object Global : Context, JSContext("GLOBAL", null) {
-    /**
-     * Closing all contexts
-     *
-     * @throws Exception
-     */
-    override fun close() {
-        logger.info { "Shutting down GLOBAL" }
-        for (ctx in contextRegistry.values) {
-            ctx.close()
-        }
-        super.close()
-    }
-
-    private val contextRegistry = HashMap<String, Context>()
-
-    /**
-     * Get previously builder context o builder a new one
-     *
-     * @param name
-     * @return
-     */
-    @Synchronized
-    actual fun getContext(name: String): Context {
-        return contextRegistry.getOrPut(name) { JSContext(name) }
-    }
-}
-
-open class JSContext(
-    final override val name: String,
-    final override val parent: JSContext? = Global,
-    properties: Meta = EmptyMeta
-) : Context {
-
-    private val _properties = Config().apply { update(properties) }
-    override val properties: Meta
-        get() = if (parent == null) {
-            _properties
-        } else {
-            Laminate(_properties, parent.properties)
-        }
-
-    override val plugins: PluginManager by lazy { PluginManager(this) }
-    override val logger: KLogger = KotlinLogging.logger(name)
-
-    /**
-     * Free up resources associated with this context
-     *
-     * @throws Exception
-     */
-    override fun close() {
-        if (isActive) error("Can't close active context")
-        //detach all plugins
-        plugins.forEach { it.detach() }
-    }
-
-    private val activators = HashSet<Any>()
-
-    override val isActive: Boolean = !activators.isEmpty()
-
-    override fun activate(activator: Any) {
-        activators.add(activator)
-    }
-
-    override fun deactivate(activator: Any) {
-        activators.clear()
-    }
-}

dataforge-context/src/jsMain/kotlin/hep/dataforge/context/PluginRepository.kt

@@ -1,8 +1,5 @@
 package hep.dataforge.context
 
-import hep.dataforge.meta.Meta
-import kotlin.reflect.KClass
-
 
 actual object PluginRepository {
 
@@ -12,20 +9,6 @@ actual object PluginRepository {
         factories.add(factory)
     }
 
-    fun <T : Plugin> register(tag: PluginTag, type: KClass<out Plugin>, constructor: (Meta) -> T) {
-        val factory = object : PluginFactory {
-            override val tag: PluginTag = tag
-            override val type: KClass<out Plugin> = type
-
-            override fun build(meta: Meta): Plugin = constructor(meta)
-
-        }
-        register(factory)
-    }
-
-    inline fun <reified T : Plugin> register(tag: PluginTag, noinline constructor: (Meta) -> T) =
-        register(tag, T::class, constructor)
-
     /**
      * List plugins available in the repository
      */

dataforge-context/src/jvmMain/kotlin/hep/dataforge/context/ClassLoaderPlugin.kt

@@ -0,0 +1,118 @@
+/*
+ * Copyright  2018 Alexander Nozik.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package hep.dataforge.context
+
+import java.util.*
+import kotlin.reflect.KClass
+import kotlin.reflect.full.cast
+
+class ClassLoaderPlugin(val classLoader: ClassLoader) : AbstractPlugin() {
+    override val tag: PluginTag = PluginTag("classLoader", PluginTag.DATAFORGE_GROUP)
+
+    private val serviceCache: MutableMap<Class<*>, ServiceLoader<*>> = HashMap()
+
+    fun <T : Any> services(type: KClass<T>): Sequence<T> {
+        return serviceCache.getOrPut(type.java) { ServiceLoader.load(type.java, classLoader) }.asSequence()
+            .map { type.cast(it) }
+    }
+
+    companion object {
+        val DEFAULT = ClassLoaderPlugin(Global::class.java.classLoader)
+    }
+}
+
+val Context.classLoaderPlugin get() = this.plugins.get() ?: ClassLoaderPlugin.DEFAULT
+
+inline fun <reified T : Any> Context.services() = classLoaderPlugin.services(T::class)
+
+
+//open class JVMContext(
+//    final override val name: String,
+//    final override val parent: JVMContext? = Global,
+//    classLoader: ClassLoader? = null,
+//    properties: Meta = EmptyMeta
+//) : Context, AutoCloseable {
+//
+//    override val properties: Meta = if (parent == null) {
+//        properties
+//    } else {
+//        Laminate(properties, parent.properties)
+//    }
+//
+//    override val plugins: PluginManager by lazy { PluginManager(this) }
+//    override val logger: KLogger = KotlinLogging.logger(name)
+//
+//    /**
+//     * A class loader for this context. Parent class loader is used by default
+//     */
+//    open val classLoader: ClassLoader = classLoader ?: parent?.classLoader ?: Global.classLoader
+//
+//    /**
+//     * A property showing that dispatch thread is started in the context
+//     */
+//    private var started = false
+//
+//    /**
+//     * A dispatch thread executor for current context
+//     *
+//     * @return
+//     */
+//    val dispatcher: ExecutorService by lazy {
+//        logger.info("Initializing dispatch thread executor in {}", name)
+//        Executors.newSingleThreadExecutor { r ->
+//            Thread(r).apply {
+//                priority = 8 // slightly higher priority
+//                isDaemon = true
+//                name = this@JVMContext.name + "_dispatch"
+//            }.also { started = true }
+//        }
+//    }
+//
+//    private val serviceCache: MutableMap<Class<*>, ServiceLoader<*>> = HashMap()
+//
+//    fun <T : Any> services(type: KClass<T>): Sequence<T> {
+//        return serviceCache.getOrPut(type.java) { ServiceLoader.load(type.java, classLoader) }.asSequence()
+//            .map { type.cast(it) }
+//    }
+//
+//    /**
+//     * Free up resources associated with this context
+//     *
+//     * @throws Exception
+//     */
+//    override fun close() {
+//        if (isActive) error("Can't close active context")
+//        //detach all plugins
+//        plugins.forEach { it.detach() }
+//
+//        if (started) {
+//            dispatcher.shutdown()
+//        }
+//    }
+//
+//    private val activators = HashSet<WeakReference<Any>>()
+//
+//    override val isActive: Boolean = activators.all { it.get() == null }
+//
+//    override fun activate(activator: Any) {
+//        activators.add(WeakReference(activator))
+//    }
+//
+//    override fun deactivate(activator: Any) {
+//        activators.removeAll { it.get() == activator }
+//    }
+//}
+//

dataforge-context/src/jvmMain/kotlin/hep/dataforge/context/Global.kt

@@ -1,65 +0,0 @@
-/*
- * Copyright  2018 Alexander Nozik.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- */
-package hep.dataforge.context
-
-import hep.dataforge.meta.Meta
-import hep.dataforge.meta.buildMeta
-import hep.dataforge.names.toName
-import java.util.*
-import kotlin.collections.HashMap
-
-
-private fun Properties.asMeta(): Meta {
-    return buildMeta {
-        this@asMeta.forEach { key, value ->
-            set(key.toString().toName(), value)
-        }
-    }
-}
-
-/**
- * A singleton global context. Automatic root for the whole context hierarchy. Also stores the registry for active contexts.
- *
- * @author Alexander Nozik
- */
-actual object Global : Context, JVMContext("GLOBAL", null, Thread.currentThread().contextClassLoader) {
-
-    /**
-     * Closing all contexts
-     *
-     * @throws Exception
-     */
-    override fun close() {
-        logger.info("Shutting down GLOBAL")
-        for (ctx in contextRegistry.values) {
-            ctx.close()
-        }
-        super.close()
-    }
-
-    private val contextRegistry = HashMap<String, Context>()
-
-    /**
-     * Get previously builder context o builder a new one
-     *
-     * @param name
-     * @return
-     */
-    @Synchronized
-    actual fun getContext(name: String): Context {
-        return contextRegistry.getOrPut(name) { JVMContext(name) }
-    }
-}

dataforge-context/src/jvmMain/kotlin/hep/dataforge/context/JVMContext.kt

@@ -1,107 +0,0 @@
-/*
- * Copyright  2018 Alexander Nozik.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- */
-package hep.dataforge.context
-
-import hep.dataforge.meta.*
-import mu.KLogger
-import mu.KotlinLogging
-import java.lang.ref.WeakReference
-import java.util.*
-import java.util.concurrent.ExecutorService
-import java.util.concurrent.Executors
-import kotlin.collections.HashSet
-import kotlin.reflect.KClass
-import kotlin.reflect.full.cast
-
-open class JVMContext(
-    final override val name: String,
-    final override val parent: JVMContext? = Global,
-    classLoader: ClassLoader? = null,
-    properties: Meta = EmptyMeta
-) : Context, AutoCloseable {
-
-    private val _properties = Config().apply { update(properties) }
-    override val properties: Meta
-        get() = if (parent == null) {
-            _properties
-        } else {
-            Laminate(_properties, parent.properties)
-        }
-
-    override val plugins: PluginManager by lazy { PluginManager(this) }
-    override val logger: KLogger = KotlinLogging.logger(name)
-
-    /**
-     * A class loader for this context. Parent class loader is used by default
-     */
-    open val classLoader: ClassLoader = classLoader ?: parent?.classLoader ?: Global.classLoader
-
-    /**
-     * A property showing that dispatch thread is started in the context
-     */
-    private var started = false
-
-    /**
-     * A dispatch thread executor for current context
-     *
-     * @return
-     */
-    val dispatcher: ExecutorService by lazy {
-        logger.info("Initializing dispatch thread executor in {}", name)
-        Executors.newSingleThreadExecutor { r ->
-            Thread(r).apply {
-                priority = 8 // slightly higher priority
-                isDaemon = true
-                name = this@JVMContext.name + "_dispatch"
-            }.also { started = true }
-        }
-    }
-
-    private val serviceCache: MutableMap<Class<*>, ServiceLoader<*>> = HashMap()
-
-    fun <T : Any> services(type: KClass<T>): Sequence<T> {
-        return serviceCache.getOrPut(type.java) { ServiceLoader.load(type.java, classLoader) }.asSequence()
-            .map { type.cast(it) }
-    }
-
-    /**
-     * Free up resources associated with this context
-     *
-     * @throws Exception
-     */
-    override fun close() {
-        if (isActive) error("Can't close active context")
-        //detach all plugins
-        plugins.forEach { it.detach() }
-
-        if (started) {
-            dispatcher.shutdown()
-        }
-    }
-
-    private val activators = HashSet<WeakReference<Any>>()
-
-    override val isActive: Boolean = activators.all { it.get() == null }
-
-    override fun activate(activator: Any) {
-        activators.add(WeakReference(activator))
-    }
-
-    override fun deactivate(activator: Any) {
-        activators.removeAll { it.get() == activator }
-    }
-}
-

dataforge-context/src/jvmMain/kotlin/hep/dataforge/context/PluginRepository.kt

@@ -12,6 +12,6 @@ actual object PluginRepository {
      * List plugins available in the repository
      */
     actual fun list(): Sequence<PluginFactory> =
-        factories.asSequence() + Global.services(PluginFactory::class)
+        factories.asSequence() + Global.services()
 
 }

dataforge-context/src/jvmMain/kotlin/hep/dataforge/provider/Types.kt

@@ -1,6 +1,7 @@
 package hep.dataforge.provider
 
 import hep.dataforge.context.Context
+import hep.dataforge.context.members
 import kotlin.reflect.KClass
 import kotlin.reflect.full.findAnnotation
 
@@ -31,7 +32,5 @@ inline fun <reified T : Any> Provider.provideAllByType(): Sequence<T> {
 /**
  * A sequences of all objects provided by plugins with given target and type
  */
-inline fun <reified T : Any> Context.components(): Sequence<T> {
-    return plugins.asSequence().flatMap { it.provideAll(Types[T::class]) }.filterIsInstance<T>()
-}
+inline fun <reified T : Any> Context.members(): Sequence<T> = members<T>(Types[T::class])
 

dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/Meta.kt

@@ -179,4 +179,6 @@ interface Metoid {
     val meta: Meta
 }
 
-fun Value.toMeta() = buildMeta { Meta.VALUE_KEY to this }
+fun Value.toMeta() = buildMeta { Meta.VALUE_KEY to this }
+
+fun Meta.isEmpty() = this === EmptyMeta || this.items.isEmpty()

dataforge-workspace/src/commonMain/kotlin/hep/dataforge/workspace/Dependency.kt

@@ -31,12 +31,9 @@ class DataDependency(val filter: DataFilter) : Dependency() {
 
 class TaskModelDependency(val name: String, val meta: Meta, val placement: Name = EmptyName) : Dependency() {
     override fun apply(workspace: Workspace): DataNode<Any> {
-        val model =
-            workspace.tasks[name]?.build(workspace, meta) ?: error("Task with name $name not found in $workspace")
-
-        val task = workspace.tasks[model.name] ?: error("Task with name ${model.name} is not found in the workspace")
+        val task = workspace.tasks[name] ?: error("Task with name ${name} is not found in the workspace")
         if (task.isTerminal) TODO("Support terminal task")
-        val result = task.run(model)
+        val result = with(workspace) { task(meta) }
         return if (placement.isEmpty()) {
             result
         } else {

dataforge-workspace/src/commonMain/kotlin/hep/dataforge/workspace/Workspace.kt

@@ -1,7 +1,8 @@
 package hep.dataforge.workspace
 
+import hep.dataforge.context.Context
 import hep.dataforge.context.ContextAware
-import hep.dataforge.context.Named
+import hep.dataforge.context.members
 import hep.dataforge.data.Data
 import hep.dataforge.data.DataNode
 import hep.dataforge.meta.Meta
@@ -12,7 +13,7 @@ import hep.dataforge.provider.Type
 
 
 @Type(Workspace.TYPE)
-interface Workspace : ContextAware, Named, Provider {
+interface Workspace : ContextAware, Provider {
     /**
      * The whole data node for current workspace
      */
@@ -48,8 +49,40 @@ interface Workspace : ContextAware, Named, Provider {
         }
     }
 
+    operator fun <R : Any> Task<R>.invoke(config: Meta): DataNode<R> {
+        context.activate(this)
+        try {
+            val model = build(this@Workspace, config)
+            validate(model)
+            return run(model)
+        } finally {
+            context.deactivate(this)
+        }
+    }
+
+    /**
+     * Invoke a task in the workspace utilizing caching if possible
+     */
+    operator fun <R : Any> Task<R>.invoke(targetName: String): DataNode<R> {
+        val target = targets[targetName] ?: error("A target with name $targetName not found in ${this@Workspace}")
+        return invoke(target)
+    }
+
     companion object {
         const val TYPE = "workspace"
     }
 }
 
+class SimpleWorkspace(
+    override val context: Context,
+    override val data: DataNode<Any>,
+    override val targets: Map<String, Meta>,
+    tasks: Collection<Task<Any>>
+) : Workspace {
+
+    override val tasks: Map<String, Task<*>> by lazy {
+        (context.members<Task<*>>(Task.TYPE) + tasks).associate { it.name to it }
+    }
+
+}
+

dataforge-workspace/src/commonMain/kotlin/hep/dataforge/workspace/WorkspaceBuilder.kt

@@ -0,0 +1,40 @@
+package hep.dataforge.workspace
+
+import hep.dataforge.context.Context
+import hep.dataforge.context.ContextBuilder
+import hep.dataforge.data.DataTreeBuilder
+import hep.dataforge.meta.Meta
+import hep.dataforge.meta.MetaBuilder
+import hep.dataforge.meta.buildMeta
+
+/**
+ * A builder for a workspace
+ */
+class WorkspaceBuilder(var context: Context) {
+    val data = DataTreeBuilder<Any>()
+    val targets = HashMap<String, Meta>()
+    val tasks = HashSet<Task<Any>>()
+
+    fun context(action: ContextBuilder.() -> Unit) {
+        this.context = ContextBuilder().apply(action).build()
+    }
+
+    fun data(action: DataTreeBuilder<Any>.() -> Unit) = data.apply(action)
+
+    fun target(name: String, meta: Meta) {
+        targets[name] = meta
+    }
+
+    fun target(name: String, action: MetaBuilder.() -> Unit) = target(name, buildMeta(action))
+
+    fun task(task: Task<*>) {
+        tasks.add(task)
+    }
+
+    fun build(): Workspace = SimpleWorkspace(
+        context,
+        data.build(),
+        targets,
+        tasks
+    )
+}