Add magix registry access service

controls-core/README.md

@@ -0,0 +1,39 @@
+# Module controls-core
+
+
+
+## Features
+
+ - [device](src/commonMain/kotlin/space/kscience/controls/api/Device.kt) : Device API with subscription (asynchronous and pseudo-synchronous properties)
+ - [deviceMessage](src/commonMain/kotlin/space/kscience/controls/api/DeviceMessage.kt) : Specification for messages used to communicate between Controls-kt devices.
+ - [deviceHub](src/commonMain/kotlin/space/kscience/controls/api/DeviceHub.kt) : Grouping of devices into local tree-like hubs.
+
+
+## Usage
+
+## Artifact:
+
+The Maven coordinates of this project are `space.kscience:controls-core:0.2.0-dev-2`.
+
+**Gradle Groovy:**
+```groovy
+repositories {
+    maven { url 'https://repo.kotlin.link' }
+    mavenCentral()
+}
+
+dependencies {
+    implementation 'space.kscience:controls-core:0.2.0-dev-2'
+}
+```
+**Gradle Kotlin DSL:**
+```kotlin
+repositories {
+    maven("https://repo.kotlin.link")
+    mavenCentral()
+}
+
+dependencies {
+    implementation("space.kscience:controls-core:0.2.0-dev-2")
+}
+```

controls-pi/README.md

@@ -0,0 +1,32 @@
+# Module controls-pi
+
+
+
+## Usage
+
+## Artifact:
+
+The Maven coordinates of this project are `space.kscience:controls-pi:0.2.0-dev-2`.
+
+**Gradle Groovy:**
+```groovy
+repositories {
+    maven { url 'https://repo.kotlin.link' }
+    mavenCentral()
+}
+
+dependencies {
+    implementation 'space.kscience:controls-pi:0.2.0-dev-2'
+}
+```
+**Gradle Kotlin DSL:**
+```kotlin
+repositories {
+    maven("https://repo.kotlin.link")
+    mavenCentral()
+}
+
+dependencies {
+    implementation("space.kscience:controls-pi:0.2.0-dev-2")
+}
+```

magix/magix-api/src/commonMain/kotlin/space/kscience/magix/services/MagixRegistry.kt

@@ -2,7 +2,9 @@ package space.kscience.magix.services
 
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.mapNotNull
 import kotlinx.coroutines.flow.onEach
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
@@ -57,6 +59,9 @@ public class MagixRegistryErrorMessage(
     public val errorMessage: String? = null,
 ) : MagixRegistryMessage()
 
+/**
+ * Launch a magix registry loop service based on local registry
+ */
 public fun CoroutineScope.launchMagixRegistry(
     endpoint: MagixEndpoint,
     registry: MagixRegistry,
@@ -79,3 +84,28 @@ public fun CoroutineScope.launchMagixRegistry(
             }
         }
     }.launchIn(this)
+
+/**
+ * Request a property with given name and return a [Flow] of pairs (sourceEndpoint, value).
+ *
+ * Flow is ordered by response receive time.
+ * The subscriber can terminate the flow at any moment to stop subscription, or use it indefinitely to continue observing changes.
+ * To request a single value, use [Flow.first] function.
+ *
+ * If [targetEndpoint] field is provided, send request only to given endpoint.
+ */
+public suspend fun MagixEndpoint.getProperty(
+    propertyName: String,
+    user: JsonElement? = null,
+    targetEndpoint: String? = null,
+): Flow<Pair<String, JsonElement>> {
+    send(MagixRegistryMessage.format, MagixRegistryRequestMessage(propertyName), target = targetEndpoint, user = user)
+    return subscribe(
+        MagixRegistryMessage.format,
+        originFilter = targetEndpoint?.let { setOf(it) }
+    ).mapNotNull { (message, response) ->
+        if (response is MagixRegistryValueMessage && response.propertyName == propertyName) {
+            message.sourceEndpoint to response.value
+        } else null
+    }
+}