From 1414cf5a2f074a941999a2f5989bc0551a413f32 Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Mon, 30 Oct 2023 21:35:46 +0300
Subject: [PATCH] implement constructor

---
 CHANGELOG.md                                  |   1 +
 .../controls/constructor/DeviceGroup.kt       | 258 ++++++++++++++++++
 .../controls/constructor/DeviceState.kt       | 108 +++++++-
 .../controls/constructor/DeviceTree.kt        |  33 ---
 .../kscience/controls/constructor/Drive.kt    |  27 +-
 .../controls/constructor/LimitSwitch.kt       |  10 +-
 .../controls/constructor/PidRegulator.kt      |  31 ++-
 .../controls/constructor/Regulator.kt         |   3 +-
 .../controls/constructor/customState.kt       |  41 +++
 .../space/kscience/controls/api/Device.kt     |  52 ++--
 .../kscience/controls/api/DeviceMessage.kt    |   2 +-
 .../kscience/controls/manager/ClockManager.kt |  25 ++
 .../controls/manager/respondMessage.kt        |  10 +-
 .../kscience/controls/spec/DeviceBase.kt      |  10 +-
 .../controls/spec/DevicePropertySpec.kt       |  18 +-
 .../kscience/controls/spec/DeviceSpec.kt      |  14 +-
 .../controls/spec/propertySpecDelegates.kt    |  10 +-
 .../kscience/controls/client/DeviceClient.kt  |   2 +-
 .../kscience/controls/client/tangoMagix.kt    |   6 +-
 .../controls/modbus/DeviceProcessImage.kt     |  19 +-
 .../controls/opcua/server/DeviceNameSpace.kt  |  15 +-
 controls-vision/build.gradle.kts              |  13 +-
 .../controls/vision/plotExtensions.kt         |  56 ++++
 .../kscience/controls/demo/car/VirtualCar.kt  |   8 +-
 demo/constructor/build.gradle.kts             |  20 ++
 .../src/jsMain/kotlin/constructorJs.kt        |   6 +
 demo/constructor/src/jvmMain/kotlin/Main.kt   | 103 +++++++
 .../src/jvmMain/resources/logback.xml         |  11 +
 .../sciprog/devices/mks/MksPdr900Device.kt    |   2 +-
 .../pimotionmaster/fxDeviceProperties.kt      |   4 +-
 settings.gradle.kts                           |   3 +-
 31 files changed, 770 insertions(+), 151 deletions(-)
 create mode 100644 controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceGroup.kt
 delete mode 100644 controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceTree.kt
 create mode 100644 controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/customState.kt
 create mode 100644 controls-core/src/commonMain/kotlin/space/kscience/controls/manager/ClockManager.kt
 create mode 100644 controls-vision/src/commonMain/kotlin/space/kscience/controls/vision/plotExtensions.kt
 create mode 100644 demo/constructor/build.gradle.kts
 create mode 100644 demo/constructor/src/jsMain/kotlin/constructorJs.kt
 create mode 100644 demo/constructor/src/jvmMain/kotlin/Main.kt
 create mode 100644 demo/constructor/src/jvmMain/resources/logback.xml

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4f3b5a9..4083a94 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 - Low-code constructor
 
 ### Changed
+- Property caching moved from core `Device` to the `CachingDevice`
 
 ### Deprecated
 
diff --git a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceGroup.kt b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceGroup.kt
new file mode 100644
index 0000000..f7bf494
--- /dev/null
+++ b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceGroup.kt
@@ -0,0 +1,258 @@
+package space.kscience.controls.constructor
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableSharedFlow
+import space.kscience.controls.api.*
+import space.kscience.controls.manager.DeviceManager
+import space.kscience.controls.manager.install
+import space.kscience.dataforge.context.Context
+import space.kscience.dataforge.context.Factory
+import space.kscience.dataforge.meta.Laminate
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.meta.MutableMeta
+import space.kscience.dataforge.meta.get
+import space.kscience.dataforge.meta.transformations.MetaConverter
+import space.kscience.dataforge.misc.DFExperimental
+import space.kscience.dataforge.names.*
+import kotlin.collections.set
+import kotlin.coroutines.CoroutineContext
+
+
+/**
+ * A mutable group of devices and properties to be used for lightweight design and simulations.
+ */
+public class DeviceGroup(
+    public val deviceManager: DeviceManager,
+    override val meta: Meta,
+) : DeviceHub, CachingDevice {
+
+    internal class Property(
+        val state: DeviceState<out Any>,
+        val descriptor: PropertyDescriptor,
+    )
+
+    internal class Action(
+        val invoke: suspend (Meta?) -> Meta?,
+        val descriptor: ActionDescriptor,
+    )
+
+
+    override val context: Context get() = deviceManager.context
+
+    override val coroutineContext: CoroutineContext by lazy {
+        context.newCoroutineContext(
+            SupervisorJob(context.coroutineContext[Job]) +
+                    CoroutineName("Device $this") +
+                    CoroutineExceptionHandler { _, throwable ->
+                        launch {
+                            sharedMessageFlow.emit(
+                                DeviceErrorMessage(
+                                    errorMessage = throwable.message,
+                                    errorType = throwable::class.simpleName,
+                                    errorStackTrace = throwable.stackTraceToString()
+                                )
+                            )
+                        }
+                    }
+        )
+    }
+
+    private val _devices = hashMapOf<NameToken, Device>()
+
+    override val devices: Map<NameToken, Device> = _devices
+
+    public fun <D : Device> device(token: NameToken, device: D): D {
+        check(_devices[token] == null) { "A child device with name $token already exists" }
+        _devices[token] = device
+        return device
+    }
+
+    private val properties: MutableMap<Name, Property> = hashMapOf()
+
+    public fun property(descriptor: PropertyDescriptor, state: DeviceState<out Any>) {
+        val name = descriptor.name.parseAsName()
+        require(properties[name] == null) { "Can't add property with name $name. It already exists." }
+        properties[name] = Property(state, descriptor)
+    }
+
+    private val actions: MutableMap<Name, Action> = hashMapOf()
+
+    override val propertyDescriptors: Collection<PropertyDescriptor>
+        get() = properties.values.map { it.descriptor }
+
+    override val actionDescriptors: Collection<ActionDescriptor>
+        get() = actions.values.map { it.descriptor }
+
+    override suspend fun readProperty(propertyName: String): Meta =
+        properties[propertyName.parseAsName()]?.state?.valueAsMeta
+            ?: error("Property with name $propertyName not found")
+
+    override fun getProperty(propertyName: String): Meta? = properties[propertyName.parseAsName()]?.state?.valueAsMeta
+
+    override suspend fun invalidate(propertyName: String) {
+        //does nothing for this implementation
+    }
+
+    override suspend fun writeProperty(propertyName: String, value: Meta) {
+        val property = (properties[propertyName.parseAsName()]?.state as? MutableDeviceState)
+            ?: error("Property with name $propertyName not found")
+        property.valueAsMeta = value
+    }
+
+    private val sharedMessageFlow = MutableSharedFlow<DeviceMessage>()
+
+    override val messageFlow: Flow<DeviceMessage>
+        get() = sharedMessageFlow
+
+    override suspend fun execute(actionName: String, argument: Meta?): Meta? {
+        val action = actions[actionName] ?: error("Action with name $actionName not found")
+        return action.invoke(argument)
+    }
+
+    @DFExperimental
+    override var lifecycleState: DeviceLifecycleState = DeviceLifecycleState.STOPPED
+        private set(value) {
+            if (field != value) {
+                launch {
+                    sharedMessageFlow.emit(
+                        DeviceLifeCycleMessage(value)
+                    )
+                }
+            }
+            field = value
+        }
+
+
+    @OptIn(DFExperimental::class)
+    override suspend fun start() {
+        lifecycleState = DeviceLifecycleState.STARTING
+        super.start()
+        devices.values.forEach {
+            it.start()
+        }
+        lifecycleState = DeviceLifecycleState.STARTED
+    }
+
+    @OptIn(DFExperimental::class)
+    override fun stop() {
+        devices.values.forEach {
+            it.stop()
+        }
+        super.stop()
+        lifecycleState = DeviceLifecycleState.STOPPED
+    }
+
+    public companion object {
+
+    }
+}
+
+public fun DeviceManager.deviceGroup(
+    name: String = "@group",
+    meta: Meta = Meta.EMPTY,
+    block: DeviceGroup.() -> Unit,
+): DeviceGroup {
+    val group = DeviceGroup(this, meta).apply(block)
+    install(name, group)
+    return group
+}
+
+private fun DeviceGroup.getOrCreateGroup(name: Name): DeviceGroup {
+    return when (name.length) {
+        0 -> this
+        1 -> {
+            val token = name.first()
+            when (val d = devices[token]) {
+                null -> device(
+                    token,
+                    DeviceGroup(deviceManager, meta[token] ?: Meta.EMPTY)
+                )
+
+                else -> (d as? DeviceGroup) ?: error("Device $name is not a DeviceGroup")
+            }
+        }
+
+        else -> getOrCreateGroup(name.first().asName()).getOrCreateGroup(name.cutFirst())
+    }
+}
+
+/**
+ * Register a device at given [name] path
+ */
+public fun <D : Device> DeviceGroup.device(name: Name, device: D): D {
+    return when (name.length) {
+        0 -> error("Can't use empty name for a child device")
+        1 -> device(name.first(), device)
+        else -> getOrCreateGroup(name.cutLast()).device(name.tokens.last(), device)
+    }
+}
+
+public fun <D: Device> DeviceGroup.device(name: String, device: D): D = device(name.parseAsName(), device)
+
+/**
+ * Add a device creating intermediate groups if necessary. If device with given [name] already exists, throws an error.
+ */
+public fun DeviceGroup.device(name: Name, factory: Factory<Device>, deviceMeta: Meta? = null): Device {
+    val newDevice = factory.build(deviceManager.context, Laminate(deviceMeta, meta[name]))
+    device(name, newDevice)
+    return newDevice
+}
+
+public fun DeviceGroup.device(
+    name: String,
+    factory: Factory<Device>,
+    metaBuilder: (MutableMeta.() -> Unit)? = null,
+): Device = device(name.parseAsName(), factory, metaBuilder?.let { Meta(it) })
+
+/**
+ * Create or edit a group with a given [name].
+ */
+public fun DeviceGroup.deviceGroup(name: Name, block: DeviceGroup.() -> Unit): DeviceGroup =
+    getOrCreateGroup(name).apply(block)
+
+public fun DeviceGroup.deviceGroup(name: String, block: DeviceGroup.() -> Unit): DeviceGroup =
+    deviceGroup(name.parseAsName(), block)
+
+public fun <T : Any> DeviceGroup.property(
+    name: String,
+    state: DeviceState<T>,
+    descriptorBuilder: PropertyDescriptor.() -> Unit = {},
+): DeviceState<T> {
+    property(
+        PropertyDescriptor(name).apply(descriptorBuilder),
+        state
+    )
+    return state
+}
+
+public fun <T : Any> DeviceGroup.mutableProperty(
+    name: String,
+    state: MutableDeviceState<T>,
+    descriptorBuilder: PropertyDescriptor.() -> Unit = {},
+): MutableDeviceState<T> {
+    property(
+        PropertyDescriptor(name).apply(descriptorBuilder),
+        state
+    )
+    return state
+}
+
+public fun <T : Any> DeviceGroup.virtualProperty(
+    name: String,
+    initialValue: T,
+    converter: MetaConverter<T>,
+    descriptorBuilder: PropertyDescriptor.() -> Unit = {},
+): MutableDeviceState<T> {
+    val state = VirtualDeviceState<T>(converter, initialValue)
+    return mutableProperty(name, state, descriptorBuilder)
+}
+
+/**
+ * Create a virtual [MutableDeviceState], but do not register it to a device
+ */
+@Suppress("UnusedReceiverParameter")
+public fun <T : Any> DeviceGroup.standAloneProperty(
+    initialValue: T,
+    converter: MetaConverter<T>,
+): MutableDeviceState<T> = VirtualDeviceState<T>(converter, initialValue)
\ No newline at end of file
diff --git a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceState.kt b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceState.kt
index 2e6461f..783752a 100644
--- a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceState.kt
+++ b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceState.kt
@@ -1,6 +1,12 @@
 package space.kscience.controls.constructor
 
-import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.launch
+import space.kscience.controls.api.Device
+import space.kscience.controls.api.PropertyChangedMessage
+import space.kscience.controls.spec.DevicePropertySpec
+import space.kscience.controls.spec.MutableDevicePropertySpec
+import space.kscience.controls.spec.name
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.meta.transformations.MetaConverter
 
@@ -12,14 +18,106 @@ public interface DeviceState<T> {
     public val value: T
 
     public val valueFlow: Flow<T>
-
-    public val metaFlow: Flow<Meta>
 }
 
+public val <T> DeviceState<T>.metaFlow: Flow<Meta> get() = valueFlow.map(converter::objectToMeta)
+
+public val <T> DeviceState<T>.valueAsMeta: Meta get() = converter.objectToMeta(value)
+
 
 /**
  * A mutable state of a device
  */
-public interface MutableDeviceState<T> : DeviceState<T>{
+public interface MutableDeviceState<T> : DeviceState<T> {
     override var value: T
-}
\ No newline at end of file
+}
+
+public var <T : Any> MutableDeviceState<T>.valueAsMeta: Meta
+    get() = converter.objectToMeta(value)
+    set(arg) {
+        value = converter.metaToObject(arg) ?: error("Conversion for meta $arg to property type with $converter failed")
+    }
+
+/**
+ * A [MutableDeviceState] that does not correspond to a physical state
+ */
+public class VirtualDeviceState<T>(
+    override val converter: MetaConverter<T>,
+    initialValue: T,
+) : MutableDeviceState<T> {
+    private val flow = MutableStateFlow(initialValue)
+    override val valueFlow: Flow<T> get() = flow
+
+    override var value: T by flow::value
+}
+
+private open class BoundDeviceState<T>(
+    override val converter: MetaConverter<T>,
+    val device: Device,
+    val propertyName: String,
+    private val initialValue: T,
+) : DeviceState<T> {
+
+    override val valueFlow: StateFlow<T> = device.messageFlow.filterIsInstance<PropertyChangedMessage>().filter {
+        it.property == propertyName
+    }.mapNotNull {
+        converter.metaToObject(it.value)
+    }.stateIn(device.context, SharingStarted.Eagerly, initialValue)
+
+    override val value: T get() = valueFlow.value
+}
+
+/**
+ * Bind a read-only [DeviceState] to a [Device] property
+ */
+public suspend fun <T> Device.bindStateToProperty(
+    propertyName: String,
+    metaConverter: MetaConverter<T>,
+): DeviceState<T> {
+    val initialValue = metaConverter.metaToObject(readProperty(propertyName)) ?: error("Conversion of property failed")
+    return BoundDeviceState(metaConverter, this, propertyName, initialValue)
+}
+
+public suspend fun <D : Device, T> D.bindStateToProperty(
+    propertySpec: DevicePropertySpec<D, T>,
+): DeviceState<T> = bindStateToProperty(propertySpec.name, propertySpec.converter)
+
+public fun <T, R> DeviceState<T>.map(
+    converter: MetaConverter<R>, mapper: (T) -> R,
+): DeviceState<R> = object : DeviceState<R> {
+    override val converter: MetaConverter<R> = converter
+    override val value: R
+        get() = mapper(this@map.value)
+
+    override val valueFlow: Flow<R> = this@map.valueFlow.map(mapper)
+}
+
+private class MutableBoundDeviceState<T>(
+    converter: MetaConverter<T>,
+    device: Device,
+    propertyName: String,
+    initialValue: T,
+) : BoundDeviceState<T>(converter, device, propertyName, initialValue), MutableDeviceState<T> {
+
+    override var value: T
+        get() = valueFlow.value
+        set(newValue) {
+            device.launch {
+                device.writeProperty(propertyName, converter.objectToMeta(newValue))
+            }
+        }
+}
+
+public suspend fun <T> Device.bindMutableStateToProperty(
+    propertyName: String,
+    metaConverter: MetaConverter<T>,
+): MutableDeviceState<T> {
+    val initialValue = metaConverter.metaToObject(readProperty(propertyName)) ?: error("Conversion of property failed")
+    return MutableBoundDeviceState(metaConverter, this, propertyName, initialValue)
+}
+
+public suspend fun <D : Device, T> D.bindMutableStateToProperty(
+    propertySpec: MutableDevicePropertySpec<D, T>,
+): MutableDeviceState<T> = bindMutableStateToProperty(propertySpec.name, propertySpec.converter)
+
+
diff --git a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceTree.kt b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceTree.kt
deleted file mode 100644
index 8d971bb..0000000
--- a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/DeviceTree.kt
+++ /dev/null
@@ -1,33 +0,0 @@
-package space.kscience.controls.constructor
-
-import space.kscience.controls.api.Device
-import space.kscience.controls.api.DeviceHub
-import space.kscience.controls.manager.DeviceManager
-import space.kscience.dataforge.context.Factory
-import space.kscience.dataforge.meta.Meta
-import space.kscience.dataforge.meta.get
-import space.kscience.dataforge.names.NameToken
-import kotlin.collections.component1
-import kotlin.collections.component2
-import kotlin.collections.set
-
-
-public class DeviceTree(
-    public val deviceManager: DeviceManager,
-    public val meta: Meta,
-    builder: Builder,
-) : DeviceHub {
-    public class Builder(public val manager: DeviceManager) {
-        internal val childrenFactories = mutableMapOf<NameToken, Factory<Device>>()
-
-        public fun <D : Device> device(name: String, factory: Factory<Device>) {
-            childrenFactories[NameToken.parse(name)] = factory
-        }
-    }
-
-    override val devices: Map<NameToken, Device> = builder.childrenFactories.mapValues { (token, factory) ->
-        val devicesMeta = meta["devices"]
-        factory.build(deviceManager.context, devicesMeta?.get(token) ?: Meta.EMPTY)
-    }
-
-}
\ No newline at end of file
diff --git a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/Drive.kt b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/Drive.kt
index 6ac5a07..8111ff6 100644
--- a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/Drive.kt
+++ b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/Drive.kt
@@ -4,12 +4,9 @@ import kotlinx.coroutines.Job
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
-import kotlinx.datetime.Clock
 import space.kscience.controls.api.Device
-import space.kscience.controls.spec.DeviceBySpec
-import space.kscience.controls.spec.DevicePropertySpec
-import space.kscience.controls.spec.DeviceSpec
-import space.kscience.controls.spec.doubleProperty
+import space.kscience.controls.manager.clock
+import space.kscience.controls.spec.*
 import space.kscience.dataforge.context.Context
 import space.kscience.dataforge.meta.double
 import space.kscience.dataforge.meta.get
@@ -33,7 +30,7 @@ public interface Drive : Device {
     public val position: Double
 
     public companion object : DeviceSpec<Drive>() {
-        public val force: DevicePropertySpec<Drive, Double> by Drive.property(
+        public val force: MutableDevicePropertySpec<Drive, Double> by Drive.mutableProperty(
             MetaConverter.double,
             Drive::force
         )
@@ -48,16 +45,15 @@ public interface Drive : Device {
 public class VirtualDrive(
     context: Context,
     private val mass: Double,
-    position: Double,
+    public val positionState: MutableDeviceState<Double>,
 ) : Drive, DeviceBySpec<Drive>(Drive, context) {
 
     private val dt = meta["time.step"].double?.milliseconds ?: 5.milliseconds
-    private val clock = Clock.System
+    private val clock = context.clock
 
     override var force: Double = 0.0
 
-    override var position: Double = position
-        private set
+    override val position: Double get() = positionState.value
 
     public var velocity: Double = 0.0
         private set
@@ -76,10 +72,10 @@ public class VirtualDrive(
                 lastTime = realTime
 
                 // compute new value based on velocity and acceleration from the previous step
-                position += velocity * dtSeconds + force/mass * dtSeconds.pow(2) / 2
+                positionState.value += velocity * dtSeconds + force / mass * dtSeconds.pow(2) / 2
 
                 // compute new velocity based on acceleration on the previous step
-                velocity += force/mass * dtSeconds
+                velocity += force / mass * dtSeconds
             }
         }
     }
@@ -89,3 +85,10 @@ public class VirtualDrive(
     }
 }
 
+public suspend fun Drive.stateOfForce(): MutableDeviceState<Double> = bindMutableStateToProperty(Drive.force)
+
+public fun DeviceGroup.virtualDrive(
+    name: String,
+    mass: Double,
+    positionState: MutableDeviceState<Double>,
+): VirtualDrive = device(name, VirtualDrive(context, mass, positionState))
\ No newline at end of file
diff --git a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/LimitSwitch.kt b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/LimitSwitch.kt
index dd0dfed..f692e00 100644
--- a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/LimitSwitch.kt
+++ b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/LimitSwitch.kt
@@ -6,6 +6,7 @@ import space.kscience.controls.spec.DevicePropertySpec
 import space.kscience.controls.spec.DeviceSpec
 import space.kscience.controls.spec.booleanProperty
 import space.kscience.dataforge.context.Context
+import space.kscience.dataforge.names.parseAsName
 
 
 /**
@@ -25,7 +26,10 @@ public interface LimitSwitch : Device {
  */
 public class VirtualLimitSwitch(
     context: Context,
-    private val lockedFunction: () -> Boolean,
+    public val lockedState: DeviceState<Boolean>,
 ) : DeviceBySpec<LimitSwitch>(LimitSwitch, context), LimitSwitch {
-    override val locked: Boolean get() = lockedFunction()
-}
\ No newline at end of file
+    override val locked: Boolean get() = lockedState.value
+}
+
+public fun DeviceGroup.virtualLimitSwitch(name: String, lockedState: DeviceState<Boolean>): VirtualLimitSwitch =
+    device(name.parseAsName(), VirtualLimitSwitch(context, lockedState))
\ No newline at end of file
diff --git a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/PidRegulator.kt b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/PidRegulator.kt
index 4a4d0f3..e8e2ec3 100644
--- a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/PidRegulator.kt
+++ b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/PidRegulator.kt
@@ -6,25 +6,33 @@ import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
-import kotlinx.datetime.Clock
 import kotlinx.datetime.Instant
+import space.kscience.controls.manager.clock
 import space.kscience.controls.spec.DeviceBySpec
 import kotlin.time.Duration
 import kotlin.time.Duration.Companion.milliseconds
 import kotlin.time.DurationUnit
 
+/**
+ * Pid regulator parameters
+ */
+public data class PidParameters(
+    public val kp: Double,
+    public val ki: Double,
+    public val kd: Double,
+    public val timeStep: Duration = 1.milliseconds,
+)
+
 /**
  * A drive with PID regulator
  */
 public class PidRegulator(
     public val drive: Drive,
-    public val kp: Double,
-    public val ki: Double,
-    public val kd: Double,
-    private val dt: Duration = 1.milliseconds,
-    private val clock: Clock = Clock.System,
+    public val pidParameters: PidParameters,
 ) : DeviceBySpec<Regulator>(Regulator, drive.context), Regulator {
 
+    private val clock = drive.context.clock
+
     override var target: Double = drive.position
 
     private var lastTime: Instant = clock.now()
@@ -41,7 +49,7 @@ public class PidRegulator(
         drive.start()
         updateJob = launch {
             while (isActive) {
-                delay(dt)
+                delay(pidParameters.timeStep)
                 mutex.withLock {
                     val realTime = clock.now()
                     val delta = target - position
@@ -53,7 +61,7 @@ public class PidRegulator(
                     lastTime = realTime
                     lastPosition = drive.position
 
-                    drive.force = kp * delta + ki * integral + kd * derivative
+                    drive.force = pidParameters.kp * delta + pidParameters.ki * integral + pidParameters.kd * derivative
                 }
             }
         }
@@ -64,5 +72,10 @@ public class PidRegulator(
     }
 
     override val position: Double get() = drive.position
+}
 
-}
\ No newline at end of file
+public fun DeviceGroup.pid(
+    name: String,
+    drive: Drive,
+    pidParameters: PidParameters,
+): PidRegulator = device(name, PidRegulator(drive, pidParameters))
\ No newline at end of file
diff --git a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/Regulator.kt b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/Regulator.kt
index fa43b57..71cb3b0 100644
--- a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/Regulator.kt
+++ b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/Regulator.kt
@@ -3,6 +3,7 @@ package space.kscience.controls.constructor
 import space.kscience.controls.api.Device
 import space.kscience.controls.spec.DevicePropertySpec
 import space.kscience.controls.spec.DeviceSpec
+import space.kscience.controls.spec.MutableDevicePropertySpec
 import space.kscience.controls.spec.doubleProperty
 import space.kscience.dataforge.meta.transformations.MetaConverter
 
@@ -22,7 +23,7 @@ public interface Regulator : Device {
     public val position: Double
 
     public companion object : DeviceSpec<Regulator>() {
-        public val target: DevicePropertySpec<Regulator, Double> by property(MetaConverter.double, Regulator::target)
+        public val target: MutableDevicePropertySpec<Regulator, Double> by mutableProperty(MetaConverter.double, Regulator::target)
 
         public val position: DevicePropertySpec<Regulator, Double> by doubleProperty { position }
     }
diff --git a/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/customState.kt b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/customState.kt
new file mode 100644
index 0000000..e6a29a5
--- /dev/null
+++ b/controls-constructor/src/commonMain/kotlin/space/kscience/controls/constructor/customState.kt
@@ -0,0 +1,41 @@
+package space.kscience.controls.constructor
+
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import space.kscience.dataforge.meta.transformations.MetaConverter
+
+
+/**
+ *  A state describing a [Double] value in the [range]
+ */
+public class DoubleRangeState(
+    initialValue: Double,
+    public val range: ClosedFloatingPointRange<Double>,
+) : MutableDeviceState<Double> {
+
+    init {
+        require(initialValue in range) { "Initial value should be in range" }
+    }
+
+    override val converter: MetaConverter<Double> = MetaConverter.double
+
+    private val _valueFlow = MutableStateFlow(initialValue)
+
+    override var value: Double
+        get() = _valueFlow.value
+        set(newValue) {
+            _valueFlow.value = newValue.coerceIn(range)
+        }
+
+    override val valueFlow: StateFlow<Double> get() = _valueFlow
+
+    /**
+     * A state showing that the range is on its lower boundary
+     */
+    public val atStartState: DeviceState<Boolean> = map(MetaConverter.boolean) { it == range.start }
+
+    /**
+     * A state showing that the range is on its higher boundary
+     */
+    public val atEndState: DeviceState<Boolean> = map(MetaConverter.boolean) { it == range.endInclusive }
+}
\ No newline at end of file
diff --git a/controls-core/src/commonMain/kotlin/space/kscience/controls/api/Device.kt b/controls-core/src/commonMain/kotlin/space/kscience/controls/api/Device.kt
index 872a5e6..f967c89 100644
--- a/controls-core/src/commonMain/kotlin/space/kscience/controls/api/Device.kt
+++ b/controls-core/src/commonMain/kotlin/space/kscience/controls/api/Device.kt
@@ -3,10 +3,7 @@ package space.kscience.controls.api
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.cancel
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.filterIsInstance
-import kotlinx.coroutines.flow.launchIn
-import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.flow.*
 import kotlinx.serialization.Serializable
 import space.kscience.controls.api.Device.Companion.DEVICE_TARGET
 import space.kscience.dataforge.context.ContextAware
@@ -74,18 +71,6 @@ public interface Device : ContextAware, CoroutineScope {
      */
     public suspend fun readProperty(propertyName: String): Meta
 
-    /**
-     * Get the logical state of property or return null if it is invalid
-     */
-    public fun getProperty(propertyName: String): Meta?
-
-    /**
-     * Invalidate property (set logical state to invalid)
-     *
-     * This message is suspended to provide lock-free local property changes (they require coroutine context).
-     */
-    public suspend fun invalidate(propertyName: String)
-
     /**
      * Set property [value] for a property with name [propertyName].
      * In rare cases could suspend if the [Device] supports command queue, and it is full at the moment.
@@ -126,17 +111,38 @@ public interface Device : ContextAware, CoroutineScope {
     }
 }
 
+/**
+ * Device that caches properties values
+ */
+public interface CachingDevice : Device {
+
+    /**
+     * Immediately (without waiting) get the cached (logical) state of property or return null if it is invalid
+     */
+    public fun getProperty(propertyName: String): Meta?
+
+    /**
+     * Invalidate property (set logical state to invalid).
+     *
+     * This message is suspended to provide lock-free local property changes (they require coroutine context).
+     */
+    public suspend fun invalidate(propertyName: String)
+}
+
 /**
  * Get the logical state of property or suspend to read the physical value.
  */
-public suspend fun Device.getOrReadProperty(propertyName: String): Meta =
+public suspend fun Device.requestProperty(propertyName: String): Meta = if (this is CachingDevice) {
     getProperty(propertyName) ?: readProperty(propertyName)
+} else {
+    readProperty(propertyName)
+}
 
 /**
  * Get a snapshot of the device logical state
  *
  */
-public fun Device.getAllProperties(): Meta = Meta {
+public fun CachingDevice.getAllProperties(): Meta = Meta {
     for (descriptor in propertyDescriptors) {
         setMeta(Name.parse(descriptor.name), getProperty(descriptor.name))
     }
@@ -148,5 +154,11 @@ public fun Device.getAllProperties(): Meta = Meta {
 public fun Device.onPropertyChange(
     scope: CoroutineScope = this,
     callback: suspend PropertyChangedMessage.() -> Unit,
-): Job =
-    messageFlow.filterIsInstance<PropertyChangedMessage>().onEach(callback).launchIn(scope)
+): Job = messageFlow.filterIsInstance<PropertyChangedMessage>().onEach(callback).launchIn(scope)
+
+/**
+ * A [Flow] of property change messages for specific property.
+ */
+public fun Device.propertyMessageFlow(propertyName: String): Flow<PropertyChangedMessage> = messageFlow
+    .filterIsInstance<PropertyChangedMessage>()
+    .filter { it.property == propertyName }
diff --git a/controls-core/src/commonMain/kotlin/space/kscience/controls/api/DeviceMessage.kt b/controls-core/src/commonMain/kotlin/space/kscience/controls/api/DeviceMessage.kt
index 32df1bb..b3436e9 100644
--- a/controls-core/src/commonMain/kotlin/space/kscience/controls/api/DeviceMessage.kt
+++ b/controls-core/src/commonMain/kotlin/space/kscience/controls/api/DeviceMessage.kt
@@ -71,7 +71,7 @@ public data class PropertyChangedMessage(
 @SerialName("property.set")
 public data class PropertySetMessage(
     public val property: String,
-    public val value: Meta?,
+    public val value: Meta,
     override val sourceDevice: Name? = null,
     override val targetDevice: Name,
     override val comment: String? = null,
diff --git a/controls-core/src/commonMain/kotlin/space/kscience/controls/manager/ClockManager.kt b/controls-core/src/commonMain/kotlin/space/kscience/controls/manager/ClockManager.kt
new file mode 100644
index 0000000..ca69b91
--- /dev/null
+++ b/controls-core/src/commonMain/kotlin/space/kscience/controls/manager/ClockManager.kt
@@ -0,0 +1,25 @@
+package space.kscience.controls.manager
+
+import kotlinx.datetime.Clock
+import space.kscience.dataforge.context.AbstractPlugin
+import space.kscience.dataforge.context.Context
+import space.kscience.dataforge.context.PluginFactory
+import space.kscience.dataforge.context.PluginTag
+import space.kscience.dataforge.meta.Meta
+
+public class ClockManager : AbstractPlugin() {
+    override val tag: PluginTag get() = DeviceManager.tag
+
+    public val clock: Clock by lazy {
+        //TODO add clock customization
+        Clock.System
+    }
+
+    public companion object : PluginFactory<ClockManager> {
+        override val tag: PluginTag = PluginTag("clock", group = PluginTag.DATAFORGE_GROUP)
+
+        override fun build(context: Context, meta: Meta): ClockManager = ClockManager()
+    }
+}
+
+public val Context.clock: Clock get() = plugins[ClockManager]?.clock ?: Clock.System
\ No newline at end of file
diff --git a/controls-core/src/commonMain/kotlin/space/kscience/controls/manager/respondMessage.kt b/controls-core/src/commonMain/kotlin/space/kscience/controls/manager/respondMessage.kt
index d3abc03..4d319af 100644
--- a/controls-core/src/commonMain/kotlin/space/kscience/controls/manager/respondMessage.kt
+++ b/controls-core/src/commonMain/kotlin/space/kscience/controls/manager/respondMessage.kt
@@ -17,21 +17,17 @@ public suspend fun Device.respondMessage(deviceTarget: Name, request: DeviceMess
         is PropertyGetMessage -> {
             PropertyChangedMessage(
                 property = request.property,
-                value = getOrReadProperty(request.property),
+                value = requestProperty(request.property),
                 sourceDevice = deviceTarget,
                 targetDevice = request.sourceDevice
             )
         }
 
         is PropertySetMessage -> {
-            if (request.value == null) {
-                invalidate(request.property)
-            } else {
-                writeProperty(request.property, request.value)
-            }
+            writeProperty(request.property, request.value)
             PropertyChangedMessage(
                 property = request.property,
-                value = getOrReadProperty(request.property),
+                value = requestProperty(request.property),
                 sourceDevice = deviceTarget,
                 targetDevice = request.sourceDevice
             )
diff --git a/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DeviceBase.kt b/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DeviceBase.kt
index da730f8..43574cf 100644
--- a/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DeviceBase.kt
+++ b/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DeviceBase.kt
@@ -20,7 +20,7 @@ import kotlin.coroutines.CoroutineContext
  * Write a meta [item] to [device]
  */
 @OptIn(InternalDeviceAPI::class)
-private suspend fun <D : Device, T> WritableDevicePropertySpec<D, T>.writeMeta(device: D, item: Meta) {
+private suspend fun <D : Device, T> MutableDevicePropertySpec<D, T>.writeMeta(device: D, item: Meta) {
     write(device, converter.metaToObject(item) ?: error("Meta $item could not be read with $converter"))
 }
 
@@ -48,7 +48,7 @@ private suspend fun <D : Device, I, O> DeviceActionSpec<D, I, O>.executeWithMeta
 public abstract class DeviceBase<D : Device>(
     final override val context: Context,
     final override val meta: Meta = Meta.EMPTY,
-) : Device {
+) : CachingDevice {
 
     /**
      * Collection of property specifications
@@ -166,7 +166,7 @@ public abstract class DeviceBase<D : Device>(
                 propertyChanged(propertyName, value)
             }
 
-            is WritableDevicePropertySpec -> {
+            is MutableDevicePropertySpec -> {
                 //if there is a writeable property with a given name, invalidate logical and write physical
                 invalidate(propertyName)
                 property.writeMeta(self, value)
@@ -189,8 +189,8 @@ public abstract class DeviceBase<D : Device>(
     }
 
     @DFExperimental
-    override var lifecycleState: DeviceLifecycleState = DeviceLifecycleState.STOPPED
-        protected set(value) {
+    final override var lifecycleState: DeviceLifecycleState = DeviceLifecycleState.STOPPED
+        private set(value) {
             if (field != value) {
                 launch {
                     sharedMessageFlow.emit(
diff --git a/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DevicePropertySpec.kt b/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DevicePropertySpec.kt
index c42a23e..cb511ea 100644
--- a/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DevicePropertySpec.kt
+++ b/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DevicePropertySpec.kt
@@ -4,10 +4,7 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
-import space.kscience.controls.api.ActionDescriptor
-import space.kscience.controls.api.Device
-import space.kscience.controls.api.PropertyChangedMessage
-import space.kscience.controls.api.PropertyDescriptor
+import space.kscience.controls.api.*
 import space.kscience.dataforge.meta.transformations.MetaConverter
 
 
@@ -44,7 +41,7 @@ public interface DevicePropertySpec<in D, T> {
 public val DevicePropertySpec<*, *>.name: String get() = descriptor.name
 
 
-public interface WritableDevicePropertySpec<in D : Device, T> : DevicePropertySpec<D, T> {
+public interface MutableDevicePropertySpec<in D : Device, T> : DevicePropertySpec<D, T> {
     /**
      * Write physical value to a device
      */
@@ -84,21 +81,20 @@ public suspend fun <T, D : Device> D.read(propertySpec: DevicePropertySpec<D, T>
 public suspend fun <T, D : DeviceBase<D>> D.readOrNull(propertySpec: DevicePropertySpec<D, T>): T? =
     readPropertyOrNull(propertySpec.name)?.let(propertySpec.converter::metaToObject)
 
-
-public operator fun <T, D : Device> D.get(propertySpec: DevicePropertySpec<D, T>): T? =
-    getProperty(propertySpec.name)?.let(propertySpec.converter::metaToObject)
+public suspend fun <T, D : Device> D.request(propertySpec: DevicePropertySpec<D, T>): T? =
+    propertySpec.converter.metaToObject(requestProperty(propertySpec.name))
 
 /**
  * Write typed property state and invalidate logical state
  */
-public suspend fun <T, D : Device> D.write(propertySpec: WritableDevicePropertySpec<D, T>, value: T) {
+public suspend fun <T, D : Device> D.write(propertySpec: MutableDevicePropertySpec<D, T>, value: T) {
     writeProperty(propertySpec.name, propertySpec.converter.objectToMeta(value))
 }
 
 /**
  * Fire and forget variant of property writing. Actual write is performed asynchronously on a [Device] scope
  */
-public operator fun <T, D : Device> D.set(propertySpec: WritableDevicePropertySpec<D, T>, value: T): Job = launch {
+public fun <T, D : Device> D.writeAsync(propertySpec: MutableDevicePropertySpec<D, T>, value: T): Job = launch {
     write(propertySpec, value)
 }
 
@@ -151,7 +147,7 @@ public fun <D : Device, T> D.useProperty(
 /**
  * Reset the logical state of a property
  */
-public suspend fun <D : Device> D.invalidate(propertySpec: DevicePropertySpec<D, *>) {
+public suspend fun <D : CachingDevice> D.invalidate(propertySpec: DevicePropertySpec<D, *>) {
     invalidate(propertySpec.name)
 }
 
diff --git a/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DeviceSpec.kt b/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DeviceSpec.kt
index 14966ca..55122d9 100644
--- a/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DeviceSpec.kt
+++ b/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/DeviceSpec.kt
@@ -72,9 +72,9 @@ public abstract class DeviceSpec<D : Device> {
         converter: MetaConverter<T>,
         readWriteProperty: KMutableProperty1<D, T>,
         descriptorBuilder: PropertyDescriptor.() -> Unit = {},
-    ): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<Any?, WritableDevicePropertySpec<D, T>>> =
+    ): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<Any?, MutableDevicePropertySpec<D, T>>> =
         PropertyDelegateProvider { _, property ->
-            val deviceProperty = object : WritableDevicePropertySpec<D, T> {
+            val deviceProperty = object : MutableDevicePropertySpec<D, T> {
 
                 override val descriptor: PropertyDescriptor = PropertyDescriptor(property.name).apply {
                     //TODO add the type from converter
@@ -123,10 +123,10 @@ public abstract class DeviceSpec<D : Device> {
         name: String? = null,
         read: suspend D.() -> T?,
         write: suspend D.(T) -> Unit,
-    ): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, WritableDevicePropertySpec<D, T>>> =
+    ): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, MutableDevicePropertySpec<D, T>>> =
         PropertyDelegateProvider { _: DeviceSpec<D>, property: KProperty<*> ->
             val propertyName = name ?: property.name
-            val deviceProperty = object : WritableDevicePropertySpec<D, T> {
+            val deviceProperty = object : MutableDevicePropertySpec<D, T> {
                 override val descriptor: PropertyDescriptor = PropertyDescriptor(propertyName, mutable = true)
                     .apply(descriptorBuilder)
                 override val converter: MetaConverter<T> = converter
@@ -138,7 +138,7 @@ public abstract class DeviceSpec<D : Device> {
                 }
             }
             _properties[propertyName] = deviceProperty
-            ReadOnlyProperty<DeviceSpec<D>, WritableDevicePropertySpec<D, T>> { _, _ ->
+            ReadOnlyProperty<DeviceSpec<D>, MutableDevicePropertySpec<D, T>> { _, _ ->
                 deviceProperty
             }
         }
@@ -218,9 +218,9 @@ public fun <T, D : DeviceBase<D>> DeviceSpec<D>.logicalProperty(
     converter: MetaConverter<T>,
     descriptorBuilder: PropertyDescriptor.() -> Unit = {},
     name: String? = null,
-): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<Any?, WritableDevicePropertySpec<D, T>>> =
+): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<Any?, MutableDevicePropertySpec<D, T>>> =
     PropertyDelegateProvider { _, property ->
-        val deviceProperty = object : WritableDevicePropertySpec<D, T> {
+        val deviceProperty = object : MutableDevicePropertySpec<D, T> {
             val propertyName = name ?: property.name
             override val descriptor: PropertyDescriptor = PropertyDescriptor(propertyName).apply {
                 //TODO add type from converter
diff --git a/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/propertySpecDelegates.kt b/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/propertySpecDelegates.kt
index ff89662..70ef94a 100644
--- a/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/propertySpecDelegates.kt
+++ b/controls-core/src/commonMain/kotlin/space/kscience/controls/spec/propertySpecDelegates.kt
@@ -97,7 +97,7 @@ public fun <D : Device> DeviceSpec<D>.booleanProperty(
     name: String? = null,
     read: suspend D.() -> Boolean?,
     write: suspend D.(Boolean) -> Unit
-): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, WritableDevicePropertySpec<D, Boolean>>> =
+): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, MutableDevicePropertySpec<D, Boolean>>> =
     mutableProperty(
         MetaConverter.boolean,
         {
@@ -117,7 +117,7 @@ public fun <D : Device> DeviceSpec<D>.numberProperty(
     name: String? = null,
     read: suspend D.() -> Number,
     write: suspend D.(Number) -> Unit
-): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, WritableDevicePropertySpec<D, Number>>> =
+): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, MutableDevicePropertySpec<D, Number>>> =
     mutableProperty(MetaConverter.number, numberDescriptor(descriptorBuilder), name, read, write)
 
 public fun <D : Device> DeviceSpec<D>.doubleProperty(
@@ -125,7 +125,7 @@ public fun <D : Device> DeviceSpec<D>.doubleProperty(
     name: String? = null,
     read: suspend D.() -> Double,
     write: suspend D.(Double) -> Unit
-): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, WritableDevicePropertySpec<D, Double>>> =
+): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, MutableDevicePropertySpec<D, Double>>> =
     mutableProperty(MetaConverter.double, numberDescriptor(descriptorBuilder), name, read, write)
 
 public fun <D : Device> DeviceSpec<D>.stringProperty(
@@ -133,7 +133,7 @@ public fun <D : Device> DeviceSpec<D>.stringProperty(
     name: String? = null,
     read: suspend D.() -> String,
     write: suspend D.(String) -> Unit
-): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, WritableDevicePropertySpec<D, String>>> =
+): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, MutableDevicePropertySpec<D, String>>> =
     mutableProperty(MetaConverter.string, descriptorBuilder, name, read, write)
 
 public fun <D : Device> DeviceSpec<D>.metaProperty(
@@ -141,5 +141,5 @@ public fun <D : Device> DeviceSpec<D>.metaProperty(
     name: String? = null,
     read: suspend D.() -> Meta,
     write: suspend D.(Meta) -> Unit
-): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, WritableDevicePropertySpec<D, Meta>>> =
+): PropertyDelegateProvider<DeviceSpec<D>, ReadOnlyProperty<DeviceSpec<D>, MutableDevicePropertySpec<D, Meta>>> =
     mutableProperty(MetaConverter.meta, descriptorBuilder, name, read, write)
\ No newline at end of file
diff --git a/controls-magix/src/commonMain/kotlin/space/kscience/controls/client/DeviceClient.kt b/controls-magix/src/commonMain/kotlin/space/kscience/controls/client/DeviceClient.kt
index 2fcecff..474f86a 100644
--- a/controls-magix/src/commonMain/kotlin/space/kscience/controls/client/DeviceClient.kt
+++ b/controls-magix/src/commonMain/kotlin/space/kscience/controls/client/DeviceClient.kt
@@ -26,7 +26,7 @@ public class DeviceClient(
     private val deviceName: Name,
     incomingFlow: Flow<DeviceMessage>,
     private val send: suspend (DeviceMessage) -> Unit,
-) : Device {
+) : CachingDevice {
 
     @OptIn(kotlinx.coroutines.ExperimentalCoroutinesApi::class)
     override val coroutineContext: CoroutineContext = newCoroutineContext(context.coroutineContext)
diff --git a/controls-magix/src/commonMain/kotlin/space/kscience/controls/client/tangoMagix.kt b/controls-magix/src/commonMain/kotlin/space/kscience/controls/client/tangoMagix.kt
index d0bdda4..9c30f8c 100644
--- a/controls-magix/src/commonMain/kotlin/space/kscience/controls/client/tangoMagix.kt
+++ b/controls-magix/src/commonMain/kotlin/space/kscience/controls/client/tangoMagix.kt
@@ -6,7 +6,7 @@ import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import kotlinx.serialization.Serializable
 import space.kscience.controls.api.get
-import space.kscience.controls.api.getOrReadProperty
+import space.kscience.controls.api.requestProperty
 import space.kscience.controls.manager.DeviceManager
 import space.kscience.dataforge.context.error
 import space.kscience.dataforge.context.logger
@@ -91,7 +91,7 @@ public fun DeviceManager.launchTangoMagix(
                 val device = get(payload.device)
                 when (payload.action) {
                     TangoAction.read -> {
-                        val value = device.getOrReadProperty(payload.name)
+                        val value = device.requestProperty(payload.name)
                         respond(request, payload) { requestPayload ->
                             requestPayload.copy(
                                 value = value,
@@ -104,7 +104,7 @@ public fun DeviceManager.launchTangoMagix(
                             device.writeProperty(payload.name, value)
                         }
                         //wait for value to be written and return final state
-                        val value = device.getOrReadProperty(payload.name)
+                        val value = device.requestProperty(payload.name)
                         respond(request, payload) { requestPayload ->
                             requestPayload.copy(
                                 value = value,
diff --git a/controls-modbus/src/main/kotlin/space/kscience/controls/modbus/DeviceProcessImage.kt b/controls-modbus/src/main/kotlin/space/kscience/controls/modbus/DeviceProcessImage.kt
index b4fae90..8f4a2b4 100644
--- a/controls-modbus/src/main/kotlin/space/kscience/controls/modbus/DeviceProcessImage.kt
+++ b/controls-modbus/src/main/kotlin/space/kscience/controls/modbus/DeviceProcessImage.kt
@@ -6,10 +6,7 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import space.kscience.controls.api.Device
-import space.kscience.controls.spec.DevicePropertySpec
-import space.kscience.controls.spec.WritableDevicePropertySpec
-import space.kscience.controls.spec.set
-import space.kscience.controls.spec.useProperty
+import space.kscience.controls.spec.*
 
 
 public class DeviceProcessImageBuilder<D : Device> internal constructor(
@@ -29,10 +26,10 @@ public class DeviceProcessImageBuilder<D : Device> internal constructor(
 
     public fun bind(
         key: ModbusRegistryKey.Coil,
-        propertySpec: WritableDevicePropertySpec<D, Boolean>,
+        propertySpec: MutableDevicePropertySpec<D, Boolean>,
     ): ObservableDigitalOut = bind(key) { coil ->
         coil.addObserver { _, _ ->
-            device[propertySpec] = coil.isSet
+            device.writeAsync(propertySpec, coil.isSet)
         }
         device.useProperty(propertySpec) { value ->
             coil.set(value)
@@ -89,10 +86,10 @@ public class DeviceProcessImageBuilder<D : Device> internal constructor(
 
     public fun bind(
         key: ModbusRegistryKey.HoldingRegister,
-        propertySpec: WritableDevicePropertySpec<D, Short>,
+        propertySpec: MutableDevicePropertySpec<D, Short>,
     ): ObservableRegister = bind(key) { register ->
         register.addObserver { _, _ ->
-            device[propertySpec] = register.toShort()
+            device.writeAsync(propertySpec, register.toShort())
         }
         device.useProperty(propertySpec) { value ->
             register.setValue(value)
@@ -121,7 +118,7 @@ public class DeviceProcessImageBuilder<D : Device> internal constructor(
     /**
      * Trigger [block] if one of register changes.
      */
-    private fun List<ObservableRegister>.onChange(block: (ByteReadPacket) -> Unit) {
+    private fun List<ObservableRegister>.onChange(block: suspend (ByteReadPacket) -> Unit) {
         var ready = false
 
         forEach { register ->
@@ -147,7 +144,7 @@ public class DeviceProcessImageBuilder<D : Device> internal constructor(
         }
     }
 
-    public fun <T> bind(key: ModbusRegistryKey.HoldingRange<T>, propertySpec: WritableDevicePropertySpec<D, T>) {
+    public fun <T> bind(key: ModbusRegistryKey.HoldingRange<T>, propertySpec: MutableDevicePropertySpec<D, T>) {
         val registers = List(key.count) {
             ObservableRegister()
         }
@@ -157,7 +154,7 @@ public class DeviceProcessImageBuilder<D : Device> internal constructor(
         }
 
         registers.onChange { packet ->
-            device[propertySpec] = key.format.readObject(packet)
+            device.write(propertySpec, key.format.readObject(packet))
         }
 
         device.useProperty(propertySpec) { value ->
diff --git a/controls-opcua/src/main/kotlin/space/kscience/controls/opcua/server/DeviceNameSpace.kt b/controls-opcua/src/main/kotlin/space/kscience/controls/opcua/server/DeviceNameSpace.kt
index a05a81d..05fc3c6 100644
--- a/controls-opcua/src/main/kotlin/space/kscience/controls/opcua/server/DeviceNameSpace.kt
+++ b/controls-opcua/src/main/kotlin/space/kscience/controls/opcua/server/DeviceNameSpace.kt
@@ -19,10 +19,7 @@ import org.eclipse.milo.opcua.stack.core.AttributeId
 import org.eclipse.milo.opcua.stack.core.Identifiers
 import org.eclipse.milo.opcua.stack.core.types.builtin.DateTime
 import org.eclipse.milo.opcua.stack.core.types.builtin.LocalizedText
-import space.kscience.controls.api.Device
-import space.kscience.controls.api.DeviceHub
-import space.kscience.controls.api.PropertyDescriptor
-import space.kscience.controls.api.onPropertyChange
+import space.kscience.controls.api.*
 import space.kscience.controls.manager.DeviceManager
 import space.kscience.dataforge.meta.Meta
 import space.kscience.dataforge.meta.MetaSerializer
@@ -31,7 +28,7 @@ import space.kscience.dataforge.names.Name
 import space.kscience.dataforge.names.plus
 
 
-public operator fun Device.get(propertyDescriptor: PropertyDescriptor): Meta? = getProperty(propertyDescriptor.name)
+public operator fun CachingDevice.get(propertyDescriptor: PropertyDescriptor): Meta? = getProperty(propertyDescriptor.name)
 
 public suspend fun Device.read(propertyDescriptor: PropertyDescriptor): Meta = readProperty(propertyDescriptor.name)
 
@@ -106,9 +103,11 @@ public class DeviceNameSpace(
                 setTypeDefinition(Identifiers.BaseDataVariableType)
             }.build()
 
-
-            device[descriptor]?.toOpc(sourceTime = null, serverTime = null)?.let {
-                node.value = it
+            // Update initial value, but only if it is cached
+            if(device is CachingDevice) {
+                device[descriptor]?.toOpc(sourceTime = null, serverTime = null)?.let {
+                    node.value = it
+                }
             }
 
             /**
diff --git a/controls-vision/build.gradle.kts b/controls-vision/build.gradle.kts
index 0b3e9f1..e1401d9 100644
--- a/controls-vision/build.gradle.kts
+++ b/controls-vision/build.gradle.kts
@@ -7,14 +7,23 @@ description = """
     Dashboard and visualization extensions for devices
 """.trimIndent()
 
-kscience{
+val visionforgeVersion = "0.3.0-dev-10"
+
+kscience {
     jvm()
     js()
     dependencies {
         api(projects.controlsCore)
+        api(projects.controlsConstructor)
+        api("space.kscience:visionforge-plotly:$visionforgeVersion")
+        api("space.kscience:visionforge-markdown:$visionforgeVersion")
+    }
+
+    jvmMain{
+        api("space.kscience:visionforge-server:$visionforgeVersion")
     }
 }
 
-readme{
+readme {
     maturity = space.kscience.gradle.Maturity.PROTOTYPE
 }
diff --git a/controls-vision/src/commonMain/kotlin/space/kscience/controls/vision/plotExtensions.kt b/controls-vision/src/commonMain/kotlin/space/kscience/controls/vision/plotExtensions.kt
new file mode 100644
index 0000000..392930c
--- /dev/null
+++ b/controls-vision/src/commonMain/kotlin/space/kscience/controls/vision/plotExtensions.kt
@@ -0,0 +1,56 @@
+package space.kscience.controls.vision
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
+import kotlinx.datetime.Clock
+import space.kscience.controls.api.Device
+import space.kscience.controls.api.propertyMessageFlow
+import space.kscience.controls.constructor.DeviceState
+import space.kscience.controls.manager.clock
+import space.kscience.dataforge.meta.ListValue
+import space.kscience.dataforge.meta.Meta
+import space.kscience.dataforge.meta.Null
+import space.kscience.dataforge.meta.Value
+import space.kscience.plotly.Plot
+import space.kscience.plotly.models.Scatter
+import space.kscience.plotly.models.TraceValues
+import space.kscience.plotly.scatter
+
+private var TraceValues.values: List<Value>
+    get() = value?.list ?: emptyList()
+    set(newValues) {
+        value = ListValue(newValues)
+    }
+
+/**
+ * Add a trace that shows a [Device] property change over time. Show only latest [pointsNumber] .
+ * @return a [Job] that handles the listener
+ */
+public fun Plot.plotDeviceProperty(
+    device: Device,
+    propertyName: String,
+    extractValue: Meta.() -> Value = { value ?: Null },
+    pointsNumber: Int = 400,
+    coroutineScope: CoroutineScope = device,
+    configuration: Scatter.() -> Unit = {},
+): Job = scatter(configuration).run {
+    val clock = device.context.clock
+    device.propertyMessageFlow(propertyName).onEach { message ->
+        x.strings = (x.strings + (message.time ?: clock.now()).toString()).takeLast(pointsNumber)
+        y.values = (y.values + message.value.extractValue()).takeLast(pointsNumber)
+    }.launchIn(coroutineScope)
+}
+
+public fun Plot.plotDeviceState(
+    scope: CoroutineScope,
+    state: DeviceState<out Number>,
+    pointsNumber: Int = 400,
+    configuration: Scatter.() -> Unit = {},
+): Job = scatter(configuration).run {
+    state.valueFlow.onEach {
+        x.strings = (x.strings + Clock.System.now().toString()).takeLast(pointsNumber)
+        y.numbers = (y.numbers + it).takeLast(pointsNumber)
+    }.launchIn(scope)
+}
\ No newline at end of file
diff --git a/demo/car/src/main/kotlin/space/kscience/controls/demo/car/VirtualCar.kt b/demo/car/src/main/kotlin/space/kscience/controls/demo/car/VirtualCar.kt
index 2ba0fdb..8ccb8a4 100644
--- a/demo/car/src/main/kotlin/space/kscience/controls/demo/car/VirtualCar.kt
+++ b/demo/car/src/main/kotlin/space/kscience/controls/demo/car/VirtualCar.kt
@@ -4,8 +4,8 @@ package space.kscience.controls.demo.car
 
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
-import kotlinx.datetime.Clock
 import kotlinx.datetime.Instant
+import space.kscience.controls.manager.clock
 import space.kscience.controls.spec.DeviceBySpec
 import space.kscience.controls.spec.doRecurring
 import space.kscience.controls.spec.read
@@ -41,6 +41,8 @@ data class Vector2D(var x: Double = 0.0, var y: Double = 0.0) : MetaRepr {
 }
 
 open class VirtualCar(context: Context, meta: Meta) : DeviceBySpec<VirtualCar>(IVirtualCar, context, meta), IVirtualCar {
+    private val clock = context.clock
+
     private val timeScale = 1e-3
 
     private val mass by meta.double(1000.0) // mass in kilograms
@@ -57,7 +59,7 @@ open class VirtualCar(context: Context, meta: Meta) : DeviceBySpec<VirtualCar>(I
 
     private var timeState: Instant? = null
 
-    private fun update(newTime: Instant = Clock.System.now()) {
+    private fun update(newTime: Instant = clock.now()) {
         //initialize time if it is not initialized
         if (timeState == null) {
             timeState = newTime
@@ -102,7 +104,7 @@ open class VirtualCar(context: Context, meta: Meta) : DeviceBySpec<VirtualCar>(I
     @OptIn(ExperimentalTime::class)
     override suspend fun onStart() {
         //initializing the clock
-        timeState = Clock.System.now()
+        timeState = clock.now()
         //starting regular updates
         doRecurring(100.milliseconds) {
             update()
diff --git a/demo/constructor/build.gradle.kts b/demo/constructor/build.gradle.kts
new file mode 100644
index 0000000..031c3a0
--- /dev/null
+++ b/demo/constructor/build.gradle.kts
@@ -0,0 +1,20 @@
+plugins {
+    id("space.kscience.gradle.mpp")
+    application
+}
+
+kscience {
+    fullStack("js/constructor.js")
+    useKtor()
+    dependencies {
+        api(projects.controlsVision)
+    }
+    jvmMain {
+        implementation("io.ktor:ktor-server-cio")
+        implementation(spclibs.logback.classic)
+    }
+}
+
+application {
+    mainClass.set("space.kscience.controls.demo.constructor.MainKt")
+}
\ No newline at end of file
diff --git a/demo/constructor/src/jsMain/kotlin/constructorJs.kt b/demo/constructor/src/jsMain/kotlin/constructorJs.kt
new file mode 100644
index 0000000..27bbc28
--- /dev/null
+++ b/demo/constructor/src/jsMain/kotlin/constructorJs.kt
@@ -0,0 +1,6 @@
+import space.kscience.visionforge.plotly.PlotlyPlugin
+import space.kscience.visionforge.runVisionClient
+
+public fun main(): Unit = runVisionClient {
+    plugin(PlotlyPlugin)
+}
\ No newline at end of file
diff --git a/demo/constructor/src/jvmMain/kotlin/Main.kt b/demo/constructor/src/jvmMain/kotlin/Main.kt
new file mode 100644
index 0000000..fdba90c
--- /dev/null
+++ b/demo/constructor/src/jvmMain/kotlin/Main.kt
@@ -0,0 +1,103 @@
+package space.kscience.controls.demo.constructor
+
+import io.ktor.server.cio.CIO
+import io.ktor.server.engine.embeddedServer
+import io.ktor.server.http.content.staticResources
+import io.ktor.server.routing.routing
+import space.kscience.controls.api.get
+import space.kscience.controls.constructor.*
+import space.kscience.controls.manager.ClockManager
+import space.kscience.controls.manager.DeviceManager
+import space.kscience.controls.manager.clock
+import space.kscience.controls.spec.doRecurring
+import space.kscience.controls.spec.name
+import space.kscience.controls.spec.write
+import space.kscience.controls.vision.plotDeviceProperty
+import space.kscience.controls.vision.plotDeviceState
+import space.kscience.dataforge.context.Context
+import space.kscience.dataforge.context.request
+import space.kscience.visionforge.VisionManager
+import space.kscience.visionforge.html.VisionPage
+import space.kscience.visionforge.plotly.PlotlyPlugin
+import space.kscience.visionforge.plotly.plotly
+import space.kscience.visionforge.server.close
+import space.kscience.visionforge.server.openInBrowser
+import space.kscience.visionforge.server.visionPage
+import kotlin.math.PI
+import kotlin.math.sin
+import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.DurationUnit
+
+@Suppress("ExtractKtorModule")
+public fun main() {
+    val context = Context {
+        plugin(DeviceManager)
+        plugin(PlotlyPlugin)
+        plugin(ClockManager)
+    }
+
+    val deviceManager = context.request(DeviceManager)
+    val visionManager = context.request(VisionManager)
+
+    val state = DoubleRangeState(0.0, -100.0..100.0)
+
+    val pidParameters = PidParameters(
+        kp = 2.5,
+        ki = 0.0,
+        kd = -0.1,
+        timeStep = 0.005.seconds
+    )
+
+    val device = deviceManager.deviceGroup {
+        val drive = virtualDrive("drive", 0.005, state)
+        val pid = pid("pid", drive, pidParameters)
+        virtualLimitSwitch("start", state.atStartState)
+        virtualLimitSwitch("end", state.atEndState)
+
+        val clock = context.clock
+        val clockStart = clock.now()
+
+        doRecurring(10.milliseconds) {
+            val timeFromStart = clock.now() - clockStart
+            val t = timeFromStart.toDouble(DurationUnit.SECONDS)
+            val freq = 0.1
+            val target = 5 * sin(2.0 * PI * freq * t) +
+                    sin(2 * PI * 21 * freq * t + 0.1 * (timeFromStart / pidParameters.timeStep))
+            pid.write(Regulator.target, target)
+        }
+    }
+
+    val server = embeddedServer(CIO, port = 7777) {
+        routing {
+            staticResources("", null, null)
+        }
+
+        visionPage(
+            visionManager,
+            VisionPage.scriptHeader("js/constructor.js")
+        ) {
+            vision {
+                plotly {
+                    plotDeviceState(this@embeddedServer, state){
+                        name = "value"
+                    }
+                    plotDeviceProperty(device["pid"], Regulator.target.name){
+                        name = "target"
+                    }
+                }
+            }
+        }
+
+    }.start(false)
+
+    server.openInBrowser()
+
+
+    println("Enter 'exit' to close server")
+    while (readlnOrNull() != "exit") {
+        //
+    }
+
+    server.close()
+}
\ No newline at end of file
diff --git a/demo/constructor/src/jvmMain/resources/logback.xml b/demo/constructor/src/jvmMain/resources/logback.xml
new file mode 100644
index 0000000..3865b14
--- /dev/null
+++ b/demo/constructor/src/jvmMain/resources/logback.xml
@@ -0,0 +1,11 @@
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT"/>
+    </root>
+</configuration>
\ No newline at end of file
diff --git a/demo/mks-pdr900/src/main/kotlin/center/sciprog/devices/mks/MksPdr900Device.kt b/demo/mks-pdr900/src/main/kotlin/center/sciprog/devices/mks/MksPdr900Device.kt
index 7771709..df54bfa 100644
--- a/demo/mks-pdr900/src/main/kotlin/center/sciprog/devices/mks/MksPdr900Device.kt
+++ b/demo/mks-pdr900/src/main/kotlin/center/sciprog/devices/mks/MksPdr900Device.kt
@@ -94,7 +94,7 @@ class MksPdr900Device(context: Context, meta: Meta) : DeviceBySpec<MksPdr900Devi
         val channel by logicalProperty(MetaConverter.int)
 
         val value by doubleProperty(read = {
-            readChannelData(get(channel) ?: DEFAULT_CHANNEL)
+            readChannelData(request(channel) ?: DEFAULT_CHANNEL)
         })
 
         val error by logicalProperty(MetaConverter.string)
diff --git a/demo/motors/src/main/kotlin/ru/mipt/npm/devices/pimotionmaster/fxDeviceProperties.kt b/demo/motors/src/main/kotlin/ru/mipt/npm/devices/pimotionmaster/fxDeviceProperties.kt
index 0328631..adef540 100644
--- a/demo/motors/src/main/kotlin/ru/mipt/npm/devices/pimotionmaster/fxDeviceProperties.kt
+++ b/demo/motors/src/main/kotlin/ru/mipt/npm/devices/pimotionmaster/fxDeviceProperties.kt
@@ -32,7 +32,7 @@ fun <D : Device, T : Any> D.fxProperty(
     }
 }
 
-fun <D : Device, T : Any> D.fxProperty(spec: WritableDevicePropertySpec<D, T>): Property<T> =
+fun <D : Device, T : Any> D.fxProperty(spec: MutableDevicePropertySpec<D, T>): Property<T> =
     object : ObjectPropertyBase<T>() {
         override fun getBean(): Any = this
         override fun getName(): String = spec.name
@@ -51,7 +51,7 @@ fun <D : Device, T : Any> D.fxProperty(spec: WritableDevicePropertySpec<D, T>):
 
             onChange { newValue ->
                 if (newValue != null) {
-                    set(spec, newValue)
+                    writeAsync(spec, newValue)
                 }
             }
         }
diff --git a/settings.gradle.kts b/settings.gradle.kts
index ee40d35..453519f 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -69,5 +69,6 @@ include(
     ":demo:car",
     ":demo:motors",
     ":demo:echo",
-    ":demo:mks-pdr900"
+    ":demo:mks-pdr900",
+    ":demo:constructor"
 )