diff --git a/src/main/kotlin/at/ac/uibk/dps/cirrina/Runtime.kt b/src/main/kotlin/at/ac/uibk/dps/cirrina/Runtime.kt
index 5c1c6bd0..378e38b1 100644
--- a/src/main/kotlin/at/ac/uibk/dps/cirrina/Runtime.kt
+++ b/src/main/kotlin/at/ac/uibk/dps/cirrina/Runtime.kt
@@ -84,7 +84,7 @@ constructor(
     eventHandler.bind(
       graph = graph,
       instanceNames = run,
-      subscribedTo = instances.values.flatMap { it.subscriptions },
+      subscribedTo = instances.values.flatMap { it.subscriptions } /*.toSet()*/,
       handlers = instances.values.map { it::pushEvent },
     )
   }
diff --git a/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/Action.kt b/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/Action.kt
index 1ec34322..7a97df39 100644
--- a/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/Action.kt
+++ b/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/Action.kt
@@ -13,7 +13,8 @@ sealed interface Action {
             description.type,
             description.mode,
             buildVariables(description.input),
-            buildEvents(description.emits),
+            description.output,
+            buildConditionalEvents(description.emits),
           )
 
         is MatchDescription ->
@@ -57,7 +58,8 @@ sealed interface Action {
         ContextVariable.lazy(k, expression)
       }
 
-    private fun buildEvents(events: List<EventDescription>) = events.map { Event.from(it) }
+    private fun buildConditionalEvents(events: List<ConditionalEventDescription>) =
+      events.map { ConditionalEvent.from(it) }
   }
 }
 
@@ -74,12 +76,13 @@ internal constructor(
   val type: String,
   val mode: InvocationMode,
   val input: List<ContextVariable>,
-  val emits: List<Event>,
+  val output: List<String>,
+  val emits: List<ConditionalEvent>,
 ) : EventRaisingAction {
-  override fun raises(): List<Event> = emits
+  override fun raises(): List<Event> = emits.map { it.event }
 
   override fun toString() =
-    "InvokeAction(type='$type', mode='$mode', input='$input', emits='$emits')"
+    "InvokeAction(type='$type', mode='$mode', input='$input', output='$output', emits='$emits')"
 }
 
 class MatchAction
diff --git a/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/ActionCommand.kt b/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/ActionCommand.kt
index 0a115cff..acfbf249 100644
--- a/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/ActionCommand.kt
+++ b/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/ActionCommand.kt
@@ -50,12 +50,30 @@ class ActionExecutor(
       val delta = measureTime {
         runCatching { service.invoke(input) }
           .onSuccess { output ->
-            action.emits.forEach { eventTemplate ->
-              val emittedEvent = eventTemplate.copy(data = output)
-              if (emittedEvent.channel == EventChannel.INTERNAL) {
-                eventHandler.propagateToParent(emittedEvent)
-              } else {
-                eventHandler.emit(emittedEvent)
+            action.output.forEach { reference ->
+              output
+                .firstOrNull { it.name == reference }
+                ?.let {
+                  runCatching { scope.extent.set(reference, it.value) }
+                    .onFailure { e ->
+                      logger.warn(e) {
+                        "failed to assign service output to variable '${reference}'"
+                      }
+                    }
+                }
+                ?: logger.warn {
+                  "service output does not contain expected variable '${reference}'"
+                }
+            }
+
+            action.emits.forEach { conditionalEvent ->
+              if (conditionalEvent.provided?.evaluate(scope.extent) != false) {
+                val emittedEvent = conditionalEvent.event.copy(data = output)
+                if (emittedEvent.channel == EventChannel.INTERNAL) {
+                  eventHandler.propagateToParent(emittedEvent)
+                } else {
+                  eventHandler.emit(emittedEvent)
+                }
               }
             }
           }
diff --git a/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/Event.kt b/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/Event.kt
index 60ce8fa8..0facfa43 100644
--- a/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/Event.kt
+++ b/src/main/kotlin/at/ac/uibk/dps/cirrina/execution/object/Event.kt
@@ -1,5 +1,6 @@
 package at.ac.uibk.dps.cirrina.execution.`object`
 
+import at.ac.uibk.dps.cirrina.csm.Csml.ConditionalEventDescription
 import at.ac.uibk.dps.cirrina.csm.Csml.EventChannel
 import at.ac.uibk.dps.cirrina.csm.Csml.EventDescription
 import at.ac.uibk.dps.cirrina.util.getInsecureUuid
@@ -29,3 +30,17 @@ data class Event(
     }
   }
 }
+
+data class ConditionalEvent(val provided: Guard?, val event: Event) {
+  override fun toString(): String =
+    "${this::class.simpleName}(provided='$provided', event='$event')"
+
+  companion object {
+    fun from(description: ConditionalEventDescription): ConditionalEvent {
+      return ConditionalEvent(
+        description.provided?.let { Guard.from(it) },
+        Event.from(description.event),
+      )
+    }
+  }
+}
diff --git a/src/main/resources/pkl/csm/csml.pkl b/src/main/resources/pkl/csm/csml.pkl
index ec2c3b67..668f6970 100644
--- a/src/main/resources/pkl/csm/csml.pkl
+++ b/src/main/resources/pkl/csm/csml.pkl
@@ -96,7 +96,13 @@ class InvokeDescription extends ActionDescription {
   type: InvocationType
   mode: InvocationMode = "remote"
   input: Context
-  emits: Listing<EventDescription>
+  output: Listing<VariableName>
+  emits: Listing<ConditionalEventDescription>
+}
+
+class ConditionalEventDescription {
+  provided: Expression?
+  event: EventDescription
 }
 
 class EvalDescription extends ActionDescription {
@@ -187,6 +193,7 @@ typealias Transition = TransitionDescription
 typealias Action = ActionDescription
 typealias Eval = EvalDescription
 typealias Invoke = InvokeDescription
+typealias ConditionalEvent = ConditionalEventDescription
 typealias Case = CaseDescription
 typealias Match = MatchDescription
 typealias Emit = EmitDescription
diff --git a/src/test/kotlin/at/ac/uibk/dps/cirrina/InvokeTest.kt b/src/test/kotlin/at/ac/uibk/dps/cirrina/InvokeTest.kt
index af3d1741..0a8fbe9c 100644
--- a/src/test/kotlin/at/ac/uibk/dps/cirrina/InvokeTest.kt
+++ b/src/test/kotlin/at/ac/uibk/dps/cirrina/InvokeTest.kt
@@ -36,7 +36,7 @@ class InvokeTest {
           val duration = measureTime { runtime.run() }
           println("invoke execution: $duration")
 
-          assertEquals(10, context.get("v"))
+          assertEquals(100, context.get("v"))
         } finally {
           server.stop(1)
         }
diff --git a/src/test/kotlin/at/ac/uibk/dps/cirrina/LoopTest.kt b/src/test/kotlin/at/ac/uibk/dps/cirrina/LoopTest.kt
new file mode 100644
index 00000000..2f5cfce8
--- /dev/null
+++ b/src/test/kotlin/at/ac/uibk/dps/cirrina/LoopTest.kt
@@ -0,0 +1,34 @@
+package at.ac.uibk.dps.cirrina
+
+import at.ac.uibk.dps.cirrina.data.DefaultDescriptions
+import at.ac.uibk.dps.cirrina.di.DaggerTestComponent
+import at.ac.uibk.dps.cirrina.di.TestModule
+import at.ac.uibk.dps.cirrina.execution.provider.ContextInMemory
+import java.time.Duration
+import kotlin.time.measureTime
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertDoesNotThrow
+import org.junit.jupiter.api.assertTimeout
+
+class LoopTest {
+  @Test
+  fun testLoopExecute() {
+    assertTimeout(Duration.ofSeconds(10)) {
+      assertDoesNotThrow {
+        val context = ContextInMemory()
+
+        val runtime =
+          DaggerTestComponent.builder()
+            .testModule(TestModule(context, DefaultDescriptions.loop, listOf("one", "two")))
+            .build()
+            .runtime()
+
+        val duration = measureTime { runtime.run() }
+        println("loop execution: $duration")
+
+        assertEquals(1, context.get("v"))
+      }
+    }
+  }
+}
diff --git a/src/test/kotlin/at/ac/uibk/dps/cirrina/data/DefaultDescriptions.kt b/src/test/kotlin/at/ac/uibk/dps/cirrina/data/DefaultDescriptions.kt
index 0b1cdf95..6b198571 100644
--- a/src/test/kotlin/at/ac/uibk/dps/cirrina/data/DefaultDescriptions.kt
+++ b/src/test/kotlin/at/ac/uibk/dps/cirrina/data/DefaultDescriptions.kt
@@ -11,4 +11,5 @@ object DefaultDescriptions {
   val noop: URI by lazy { resourceUri("pkl/noop/main.pkl") }
   val empty: URI by lazy { resourceUri("pkl/empty/main.pkl") }
   val events: URI by lazy { resourceUri("pkl/events/main.pkl") }
+  val loop: URI by lazy { resourceUri("pkl/loop/main.pkl") }
 }
diff --git a/src/test/resources/pkl/complete/main.pkl b/src/test/resources/pkl/complete/main.pkl
index 7e007f31..4f59bba7 100644
--- a/src/test/resources/pkl/complete/main.pkl
+++ b/src/test/resources/pkl/complete/main.pkl
@@ -28,7 +28,7 @@ collaborativeStateMachine {
               type = "increment"
               mode = "local"
               input { ["v"] = "x" }
-              emits { new Internal { topic = "e2" } }
+              emits { new ConditionalEvent { event = new Internal { topic = "e2" } } }
             }
           }
           exit { new Eval { expression = "e = true" } }
diff --git a/src/test/resources/pkl/invoke/main.pkl b/src/test/resources/pkl/invoke/main.pkl
index d7785ddb..b6075472 100644
--- a/src/test/resources/pkl/invoke/main.pkl
+++ b/src/test/resources/pkl/invoke/main.pkl
@@ -7,7 +7,7 @@ collaborativeStateMachine {
         ["a"] = new Initial {
           after {
             ["timeout"] = new Timeout {
-              delay = "100"
+              delay = "1"
               triggers = new Emit { event = new Internal { topic = "update" } }
             }
           }
@@ -19,24 +19,15 @@ collaborativeStateMachine {
                   type = "increment"
                   mode = "local"
                   input { ["v"] = "v" }
-                  emits { new Internal { topic = "tob" } }
+                  output { "v" }
+                  emits { new ConditionalEvent { provided = "v >= 100"; event = new Internal { topic = "tob" } } }
                 }
-                new Eval { expression = "e = e + 1" }
               }
             }
             ["tob"] = new Transition { to = "b" }
           }
         }
-        ["b"] = new State {
-          entry { new Eval { expression = "v = $v" } }
-          always {
-            new Transition {
-              to = "a"
-              provided = "v < 10"; or = "c"
-            }
-          }
-        }
-        ["c"] = new Terminal {}
+        ["b"] = new Terminal {}
       }
     }
   }
diff --git a/src/test/resources/pkl/loop/main.pkl b/src/test/resources/pkl/loop/main.pkl
new file mode 100644
index 00000000..3e78e656
--- /dev/null
+++ b/src/test/resources/pkl/loop/main.pkl
@@ -0,0 +1,49 @@
+amends "modulepath:/pkl/csm/csml.pkl"
+
+collaborativeStateMachine {
+  stateMachines {
+    ["one"] {
+      states {
+        ["a"] = new Initial {
+          entry {
+            new Emit { event { topic = "e1" }; target = "'two'" }
+          }
+          always {
+            new Transition { to = "b" }
+          }
+        }
+        ["b"] = new Terminal {}
+      }
+    }
+    ["two"] {
+      states {
+        ["a"] = new Initial {
+          after {
+            ["t"] = new Timeout {
+              delay = "1000"
+              triggers = new Emit { event = new Internal { topic = "toc" } }
+            }
+          }
+          on {
+            ["e1"] { to = "b" }
+            ["toc"] { to = "c" }
+          }
+        }
+        ["b"] {
+          entry {
+            new Eval { expression = "v =+ 1" }
+          }
+          always {
+            new Transition { to = "a"; provided = "v < 1000" }
+          }
+        }
+        ["c"] = new Terminal {}
+      }
+    }
+  }
+  persistent { ["v"] = "0" }
+}
+instances {
+  ["one"] { stateMachineName = "one" }
+  ["two"] { stateMachineName = "two" }
+}
\ No newline at end of file