diff --git a/build.gradle.kts b/build.gradle.kts
index d73b0e60..43ea9882 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -6,7 +6,7 @@ plugins {
     id("scientifik.publish") version toolsVersion apply false
 }
 
-val dataforgeVersion by extra("0.1.7")
+val dataforgeVersion by extra("0.1.8-dev-1")
 
 val bintrayRepo by extra("dataforge")
 val githubProject by extra("dataforge-core")
diff --git a/dataforge-io/src/jvmMain/kotlin/hep/dataforge/io/tcp/EnvelopeServer.kt b/dataforge-io/src/jvmMain/kotlin/hep/dataforge/io/tcp/EnvelopeServer.kt
index fc61ee49..b9569279 100644
--- a/dataforge-io/src/jvmMain/kotlin/hep/dataforge/io/tcp/EnvelopeServer.kt
+++ b/dataforge-io/src/jvmMain/kotlin/hep/dataforge/io/tcp/EnvelopeServer.kt
@@ -28,7 +28,7 @@ class EnvelopeServer(
     fun start() {
         if (job == null) {
             logger.info { "Starting envelope server on port $port" }
-            val job = scope.launch(Dispatchers.IO) {
+            job = scope.launch(Dispatchers.IO) {
                 val serverSocket = ServerSocket(port)
                 //TODO add handshake and format negotiation
                 while (isActive && !serverSocket.isClosed) {
diff --git a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/JsonMeta.kt b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/JsonMeta.kt
index 89ab1b3e..48ef6c4e 100644
--- a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/JsonMeta.kt
+++ b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/JsonMeta.kt
@@ -28,7 +28,7 @@ fun Value.toJson(descriptor: ValueDescriptor? = null): JsonElement {
 }
 
 //Use these methods to customize JSON key mapping
-private fun String.toJsonKey(descriptor: ItemDescriptor?) = descriptor?.getProperty("jsonName").string ?: toString()
+private fun String.toJsonKey(descriptor: ItemDescriptor?) = descriptor?.attributes["jsonName"].string ?: toString()
 
 //private fun NodeDescriptor?.getDescriptor(key: String) = this?.items?.get(key)
 
@@ -146,7 +146,7 @@ class JsonMeta(val json: JsonObject, val descriptor: NodeDescriptor? = null) : M
     @Suppress("UNCHECKED_CAST")
     private operator fun MutableMap<String, MetaItem<JsonMeta>>.set(key: String, value: JsonElement): Unit {
         val itemDescriptor = descriptor?.items?.get(key)
-        return when (value) {
+        when (value) {
             is JsonPrimitive -> {
                 this[key] =
                     MetaItem.ValueItem(value.toValue(itemDescriptor as? ValueDescriptor)) as MetaItem<JsonMeta>
diff --git a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/Meta.kt b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/Meta.kt
index 9650b04e..3aa5b848 100644
--- a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/Meta.kt
+++ b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/Meta.kt
@@ -170,8 +170,12 @@ interface MetaNode<out M : MetaNode<M>> : Meta {
 /**
  * The same as [Meta.get], but with specific node type
  */
-@Suppress("UNCHECKED_CAST")
-operator fun <M : MetaNode<M>> M?.get(name: Name): MetaItem<M>? = (this as Meta)[name] as MetaItem<M>?
+operator fun <M : MetaNode<M>> M?.get(name: Name): MetaItem<M>? = if( this == null) {
+    null
+} else {
+    @Suppress("UNCHECKED_CAST")
+    (this as Meta).get(name) as MetaItem<M>?
+}
 
 operator fun <M : MetaNode<M>> M?.get(key: String): MetaItem<M>? = this[key.toName()]
 
diff --git a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/MutableMetaDelegate.kt b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/MutableMetaDelegate.kt
index 0cffb3a3..39a022f4 100644
--- a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/MutableMetaDelegate.kt
+++ b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/MutableMetaDelegate.kt
@@ -99,6 +99,10 @@ fun <M : MutableMeta<M>> M.boolean(default: Boolean, key: Name? = null) =
 fun <M : MutableMeta<M>> M.number(default: Number, key: Name? = null) =
     item(default, key).transform { it.number!! }
 
+@JvmName("lazyValue")
+fun <M : MutableMeta<M>> M.string(key: Name? = null, default: () -> Value) =
+    lazyItem(key, default).transform { it.value!! }
+
 @JvmName("lazyString")
 fun <M : MutableMeta<M>> M.string(key: Name? = null, default: () -> String) =
     lazyItem(key, default).transform { it.string!! }
diff --git a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/descriptors/ItemDescriptor.kt b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/descriptors/ItemDescriptor.kt
index e025cbb1..02af4374 100644
--- a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/descriptors/ItemDescriptor.kt
+++ b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/descriptors/ItemDescriptor.kt
@@ -8,28 +8,28 @@ import hep.dataforge.values.Value
 import hep.dataforge.values.ValueType
 
 @DFBuilder
-sealed class ItemDescriptor : Scheme() {
+sealed class ItemDescriptor(val config: Config) {
 
     /**
      * True if same name siblings with this name are allowed
      *
      * @return
      */
-    var multiple: Boolean by boolean(false)
+    var multiple: Boolean by config.boolean(false)
 
     /**
      * The item description
      *
      * @return
      */
-    var info: String? by string()
+    var info: String? by config.string()
 
     /**
      * Additional attributes of an item. For example validation and widget parameters
      *
      * @return
      */
-    var attributes by config()
+    var attributes by config.node()
 
     /**
      * True if the item is required
@@ -43,7 +43,7 @@ sealed class ItemDescriptor : Scheme() {
  * Configure attributes of the descriptor
  */
 fun ItemDescriptor.attributes(block: Config.() -> Unit) {
-    (attributes ?: Config().also { this.config = it }).apply(block)
+    (attributes ?: Config().also { this.attributes = it }).apply(block)
 }
 
 /**
@@ -65,28 +65,32 @@ fun ItemDescriptor.validateItem(item: MetaItem<*>?): Boolean {
  * @author Alexander Nozik
  */
 @DFBuilder
-class NodeDescriptor private constructor() : ItemDescriptor() {
+class NodeDescriptor(config: Config = Config()) : ItemDescriptor(config) {
+    init {
+        config[IS_NODE_KEY] = true
+    }
+
     /**
      * True if the node is required
      *
      * @return
      */
-    override var required: Boolean by boolean { default == null }
+    override var required: Boolean by config.boolean { default == null }
 
     /**
      * The default for this node. Null if there is no default.
      *
      * @return
      */
-    var default by node()
+    var default by config.node()
 
     val items: Map<String, ItemDescriptor>
         get() = config.getIndexed(ITEM_KEY).mapValues { (_, item) ->
             val node = item.node ?: error("Node descriptor must be a node")
             if (node[IS_NODE_KEY].boolean == true) {
-                NodeDescriptor.wrap(node)
+                NodeDescriptor(node)
             } else {
-                ValueDescriptor.wrap(node)
+                ValueDescriptor(node)
             }
         }
 
@@ -99,7 +103,7 @@ class NodeDescriptor private constructor() : ItemDescriptor() {
             it.value.node[IS_NODE_KEY].boolean == true
         }.associate { (name, item) ->
             val node = item.node ?: error("Node descriptor must be a node")
-            name to NodeDescriptor.wrap(node)
+            name to NodeDescriptor(node)
         }
 
     /**
@@ -110,7 +114,7 @@ class NodeDescriptor private constructor() : ItemDescriptor() {
             it.value.node[IS_NODE_KEY].boolean != true
         }.associate { (name, item) ->
             val node = item.node ?: error("Node descriptor must be a node")
-            name to ValueDescriptor.wrap(node)
+            name to ValueDescriptor(node)
         }
 
     private fun buildNode(name: Name): NodeDescriptor {
@@ -122,7 +126,7 @@ class NodeDescriptor private constructor() : ItemDescriptor() {
                     it[IS_NODE_KEY] = true
                     config[token] = it
                 }
-                wrap(config)
+                NodeDescriptor(config)
             }
             else -> buildNode(name.first()?.asName()!!).buildNode(name.cutFirst())
         }
@@ -137,41 +141,37 @@ class NodeDescriptor private constructor() : ItemDescriptor() {
         config[token] = descriptor.config
     }
 
-    fun defineItem(name: Name, descriptor: ItemDescriptor) {
+    fun item(name: Name, descriptor: ItemDescriptor) {
         buildNode(name.cutLast()).newItem(name.last().toString(), descriptor)
     }
 
-    fun defineItem(name: String, descriptor: ItemDescriptor) {
-        defineItem(name.toName(), descriptor)
+    fun item(name: String, descriptor: ItemDescriptor) {
+        item(name.toName(), descriptor)
     }
 
-    fun defineNode(name: Name, block: NodeDescriptor.() -> Unit) {
-        defineItem(name, NodeDescriptor(block))
+    fun node(name: Name, block: NodeDescriptor.() -> Unit) {
+        item(name, NodeDescriptor().apply(block))
     }
 
-    fun defineNode(name: String, block: NodeDescriptor.() -> Unit) {
-        defineNode(name.toName(), block)
+    fun node(name: String, block: NodeDescriptor.() -> Unit) {
+        node(name.toName(), block)
     }
 
-    fun defineValue(name: Name, block: ValueDescriptor.() -> Unit) {
+    fun value(name: Name, block: ValueDescriptor.() -> Unit) {
         require(name.length >= 1) { "Name length for value descriptor must be non-empty" }
-        defineItem(name, ValueDescriptor(block))
+        item(name, ValueDescriptor().apply(block))
     }
 
-    fun defineValue(name: String, block: ValueDescriptor.() -> Unit) {
-        defineValue(name.toName(), block)
+    fun value(name: String, block: ValueDescriptor.() -> Unit) {
+        value(name.toName(), block)
     }
 
-    companion object : SchemeSpec<NodeDescriptor>(::NodeDescriptor) {
+    companion object{
 
         val ITEM_KEY = "item".asName()
         val IS_NODE_KEY = "@isNode".asName()
 
-        override fun empty(): NodeDescriptor {
-            return super.empty().apply {
-                config[IS_NODE_KEY] = true
-            }
-        }
+        inline operator fun invoke(block: NodeDescriptor.()->Unit) = NodeDescriptor().apply(block)
 
         //TODO infer descriptor from spec
     }
@@ -188,6 +188,8 @@ operator fun ItemDescriptor.get(name: Name): ItemDescriptor? {
     }
 }
 
+operator fun ItemDescriptor.get(name: String): ItemDescriptor? = get(name.toName())
+
 /**
  * A descriptor for meta value
  *
@@ -196,21 +198,21 @@ operator fun ItemDescriptor.get(name: Name): ItemDescriptor? {
  * @author Alexander Nozik
  */
 @DFBuilder
-class ValueDescriptor : ItemDescriptor() {
+class ValueDescriptor(config: Config = Config()) : ItemDescriptor(config) {
 
     /**
      * True if the value is required
      *
      * @return
      */
-    override var required: Boolean by boolean { default == null }
+    override var required: Boolean by config.boolean { default == null }
 
     /**
      * The default for this value. Null if there is no default.
      *
      * @return
      */
-    var default: Value? by value()
+    var default: Value? by config.value()
 
     fun default(v: Any) {
         this.default = Value.of(v)
@@ -221,7 +223,7 @@ class ValueDescriptor : ItemDescriptor() {
      *
      * @return
      */
-    var type: List<ValueType> by item {
+    var type: List<ValueType> by config.item().transform {
         it?.value?.list?.map { v -> ValueType.valueOf(v.string) } ?: emptyList()
     }
 
@@ -248,11 +250,11 @@ class ValueDescriptor : ItemDescriptor() {
      *
      * @return
      */
-    var allowedValues: List<Value> by value {
-        it?.list ?: if (type.size == 1 && type[0] === ValueType.BOOLEAN) {
-            listOf(True, False)
-        } else {
-            emptyList()
+    var allowedValues: List<Value> by config.value().transform {
+        when{
+            it?.list != null -> it.list
+            type.size == 1 && type[0] === ValueType.BOOLEAN ->    listOf(True, False)
+            else -> emptyList()
         }
     }
 
@@ -262,6 +264,4 @@ class ValueDescriptor : ItemDescriptor() {
     fun allow(vararg v: Any) {
         this.allowedValues = v.map { Value.of(it) }
     }
-
-    companion object : SchemeSpec<ValueDescriptor>(::ValueDescriptor)
 }
\ No newline at end of file
diff --git a/dataforge-meta/src/commonTest/kotlin/hep/dataforge/meta/descriptors/DescriptorTest.kt b/dataforge-meta/src/commonTest/kotlin/hep/dataforge/meta/descriptors/DescriptorTest.kt
index 77e670c8..9c022637 100644
--- a/dataforge-meta/src/commonTest/kotlin/hep/dataforge/meta/descriptors/DescriptorTest.kt
+++ b/dataforge-meta/src/commonTest/kotlin/hep/dataforge/meta/descriptors/DescriptorTest.kt
@@ -3,18 +3,19 @@ package hep.dataforge.meta.descriptors
 import hep.dataforge.values.ValueType
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
 
 class DescriptorTest {
 
     val descriptor = NodeDescriptor {
-        defineNode("aNode") {
+        node("aNode") {
             info = "A root demo node"
-            defineValue("b") {
+            value("b") {
                 info = "b number value"
                 type(ValueType.NUMBER)
             }
-            defineNode("otherNode") {
-                defineValue("otherValue") {
+            node("otherNode") {
+                value("otherValue") {
                     type(ValueType.BOOLEAN)
                     default(false)
                     info = "default value"
@@ -25,6 +26,8 @@ class DescriptorTest {
 
     @Test
     fun testAllowedValues() {
+        val child = descriptor["aNode.b"]
+        assertNotNull(child)
         val allowed = descriptor.nodes["aNode"]?.values?.get("b")?.allowedValues
         assertEquals(emptyList(), allowed)
     }
diff --git a/dataforge-workspace/src/commonMain/kotlin/hep/dataforge/workspace/TaskBuilder.kt b/dataforge-workspace/src/commonMain/kotlin/hep/dataforge/workspace/TaskBuilder.kt
index 7f359914..9ce9cf27 100644
--- a/dataforge-workspace/src/commonMain/kotlin/hep/dataforge/workspace/TaskBuilder.kt
+++ b/dataforge-workspace/src/commonMain/kotlin/hep/dataforge/workspace/TaskBuilder.kt
@@ -2,9 +2,9 @@ package hep.dataforge.workspace
 
 import hep.dataforge.context.Context
 import hep.dataforge.data.*
-import hep.dataforge.meta.descriptors.NodeDescriptor
 import hep.dataforge.meta.DFBuilder
 import hep.dataforge.meta.Meta
+import hep.dataforge.meta.descriptors.NodeDescriptor
 import hep.dataforge.meta.get
 import hep.dataforge.meta.string
 import hep.dataforge.names.Name
@@ -200,7 +200,7 @@ class TaskBuilder<R : Any>(val name: Name, val type: KClass<out R>) {
      * Use DSL to create a descriptor for this task
      */
     fun description(transform: NodeDescriptor.() -> Unit) {
-        this.descriptor = NodeDescriptor(transform)
+        this.descriptor = NodeDescriptor().apply(transform)
     }
 
     internal fun build(): GenericTask<R> {
@@ -212,7 +212,7 @@ class TaskBuilder<R : Any>(val name: Name, val type: KClass<out R>) {
         return GenericTask(
             name,
             type,
-            descriptor ?: NodeDescriptor.empty(),
+            descriptor ?: NodeDescriptor(),
             modelTransform
         ) {
             val workspace = this