diff --git a/functions/collections/impl/src/main/java/dev/restate/e2e/functions/collections/Main.java b/functions/collections/impl/src/main/java/dev/restate/e2e/functions/collections/Main.java
index 1ebe8348..16596c66 100644
--- a/functions/collections/impl/src/main/java/dev/restate/e2e/functions/collections/Main.java
+++ b/functions/collections/impl/src/main/java/dev/restate/e2e/functions/collections/Main.java
@@ -1,7 +1,6 @@
 package dev.restate.e2e.functions.collections;
 
 import dev.restate.e2e.functions.utils.ServiceRunner;
-
 import java.io.IOException;
 
 public class Main {
diff --git a/functions/coordinator/contract/src/main/proto/coordinator.proto b/functions/coordinator/contract/src/main/proto/coordinator.proto
index 818a3c9b..e20ca4ff 100644
--- a/functions/coordinator/contract/src/main/proto/coordinator.proto
+++ b/functions/coordinator/contract/src/main/proto/coordinator.proto
@@ -17,6 +17,7 @@ service Coordinator {
   rpc Complex (ComplexRequest) returns (ComplexResponse);
   rpc Timeout (Duration) returns (TimeoutResponse);
   rpc InvokeSequentially(InvokeSequentiallyRequest) returns (google.protobuf.Empty);
+  rpc InvokeSideEffects(InvokeSideEffectsRequest) returns (InvokeSideEffectsResult);
 }
 
 message Duration {
@@ -43,3 +44,11 @@ message TimeoutResponse {
 message InvokeSequentiallyRequest {
   repeated bool execute_as_background_call = 1;
 }
+
+message InvokeSideEffectsRequest {
+  bool last_is_callback = 1;
+}
+
+message InvokeSideEffectsResult {
+  int32 invoked_times = 1;
+}
\ No newline at end of file
diff --git a/functions/coordinator/impl/src/main/java/dev/restate/e2e/functions/coordinator/CoordinatorService.java b/functions/coordinator/impl/src/main/java/dev/restate/e2e/functions/coordinator/CoordinatorService.java
index 5ac37bee..f7d40d13 100644
--- a/functions/coordinator/impl/src/main/java/dev/restate/e2e/functions/coordinator/CoordinatorService.java
+++ b/functions/coordinator/impl/src/main/java/dev/restate/e2e/functions/coordinator/CoordinatorService.java
@@ -14,6 +14,7 @@
 import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicInteger;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -135,4 +136,26 @@ public void invokeSequentially(
     responseObserver.onNext(Empty.getDefaultInstance());
     responseObserver.onCompleted();
   }
+
+  @Override
+  public void invokeSideEffects(
+      InvokeSideEffectsRequest request, StreamObserver<InvokeSideEffectsResult> responseObserver) {
+    RestateContext ctx = RestateContext.current();
+
+    AtomicInteger invokedSideEffects = new AtomicInteger(0);
+
+    ctx.sideEffect(() -> invokedSideEffects.incrementAndGet());
+    ctx.sideEffect(() -> invokedSideEffects.incrementAndGet());
+    if (request.getLastIsCallback()) {
+      ctx.callback(Void.TYPE, ignored -> invokedSideEffects.incrementAndGet());
+    } else {
+      ctx.sideEffect(() -> invokedSideEffects.incrementAndGet());
+    }
+
+    responseObserver.onNext(
+        InvokeSideEffectsResult.newBuilder()
+            .setInvokedTimes(invokedSideEffects.intValue())
+            .build());
+    responseObserver.onCompleted();
+  }
 }
diff --git a/tests/src/test/kotlin/dev/restate/e2e/Containers.kt b/tests/src/test/kotlin/dev/restate/e2e/Containers.kt
index e252d678..7c55f961 100644
--- a/tests/src/test/kotlin/dev/restate/e2e/Containers.kt
+++ b/tests/src/test/kotlin/dev/restate/e2e/Containers.kt
@@ -14,10 +14,8 @@ import org.testcontainers.containers.GenericContainer
 
 object Containers {
   val COLLECTIONS_FUNCTION_SPEC =
-    FunctionSpec.builder(
-      "restatedev/e2e-collections",
-      ListServiceGrpc.getServiceDescriptor())
-      .build()
+      FunctionSpec.builder("restatedev/e2e-collections", ListServiceGrpc.getServiceDescriptor())
+          .build()
 
   val COUNTER_FUNCTION_SPEC =
       FunctionSpec.builder(
diff --git a/tests/src/test/kotlin/dev/restate/e2e/OrderingTest.kt b/tests/src/test/kotlin/dev/restate/e2e/OrderingTest.kt
index 75962cfd..f9636729 100644
--- a/tests/src/test/kotlin/dev/restate/e2e/OrderingTest.kt
+++ b/tests/src/test/kotlin/dev/restate/e2e/OrderingTest.kt
@@ -7,41 +7,45 @@ import dev.restate.e2e.functions.coordinator.InvokeSequentiallyRequest
 import dev.restate.e2e.utils.InjectBlockingStub
 import dev.restate.e2e.utils.RestateDeployer
 import dev.restate.e2e.utils.RestateDeployerExtension
+import java.util.stream.Stream
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.extension.RegisterExtension
 import org.junit.jupiter.params.ParameterizedTest
 import org.junit.jupiter.params.provider.Arguments
 import org.junit.jupiter.params.provider.MethodSource
-import java.util.stream.Stream
 
 class OrderingTest {
   companion object {
     @RegisterExtension
     val deployerExt: RestateDeployerExtension =
         RestateDeployerExtension(
-            RestateDeployer.Builder().withFunction(Containers.COORDINATOR_FUNCTION_SPEC).withFunction(Containers.COLLECTIONS_FUNCTION_SPEC).build())
+            RestateDeployer.Builder()
+                .withFunction(Containers.COORDINATOR_FUNCTION_SPEC)
+                .withFunction(Containers.COLLECTIONS_FUNCTION_SPEC)
+                .build())
 
     @JvmStatic
     fun ordering(): Stream<Arguments> {
       return Stream.of(
-        Arguments.of(booleanArrayOf(true, false, true)),
-        Arguments.of(booleanArrayOf(false, true, false))
-      )
+          Arguments.of(booleanArrayOf(true, false, true)),
+          Arguments.of(booleanArrayOf(false, true, false)))
     }
   }
 
   @ParameterizedTest
   @MethodSource
-  fun ordering(ordering: BooleanArray, @InjectBlockingStub coordinatorClient: CoordinatorBlockingStub, @InjectBlockingStub listClient: ListServiceBlockingStub) {
+  fun ordering(
+      ordering: BooleanArray,
+      @InjectBlockingStub coordinatorClient: CoordinatorBlockingStub,
+      @InjectBlockingStub listClient: ListServiceBlockingStub
+  ) {
     coordinatorClient.invokeSequentially(
-      InvokeSequentiallyRequest.newBuilder()
-        .addAllExecuteAsBackgroundCall(ordering.asIterable())
-        .build()
-    )
+        InvokeSequentiallyRequest.newBuilder()
+            .addAllExecuteAsBackgroundCall(ordering.asIterable())
+            .build())
 
     val listClientRequest = Request.newBuilder().setListName("invokeSequentially").build()
 
-    assertThat(listClient.clear(listClientRequest).valuesList)
-      .containsExactly("0", "1", "2")
+    assertThat(listClient.clear(listClientRequest).valuesList).containsExactly("0", "1", "2")
   }
 }
diff --git a/tests/src/test/kotlin/dev/restate/e2e/SideEffectTest.kt b/tests/src/test/kotlin/dev/restate/e2e/SideEffectTest.kt
new file mode 100644
index 00000000..d8d1ac84
--- /dev/null
+++ b/tests/src/test/kotlin/dev/restate/e2e/SideEffectTest.kt
@@ -0,0 +1,37 @@
+package dev.restate.e2e
+
+import dev.restate.e2e.functions.coordinator.CoordinatorGrpc.CoordinatorBlockingStub
+import dev.restate.e2e.functions.coordinator.InvokeSideEffectsRequest
+import dev.restate.e2e.utils.InjectBlockingStub
+import dev.restate.e2e.utils.RestateDeployer
+import dev.restate.e2e.utils.RestateDeployerExtension
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.RegisterExtension
+
+class SideEffectTest {
+  companion object {
+    @RegisterExtension
+    val deployerExt: RestateDeployerExtension =
+        RestateDeployerExtension(
+            RestateDeployer.Builder().withFunction(Containers.COORDINATOR_FUNCTION_SPEC).build())
+  }
+
+  @Test
+  fun sideEffectFlush(@InjectBlockingStub coordinatorClient: CoordinatorBlockingStub) {
+    assertThat(
+            coordinatorClient.invokeSideEffects(
+                InvokeSideEffectsRequest.newBuilder().setLastIsCallback(false).build()))
+        .extracting { it.invokedTimes }
+        .isEqualTo(1)
+  }
+
+  @Test
+  fun sideEffectThenCallbackFlush(@InjectBlockingStub coordinatorClient: CoordinatorBlockingStub) {
+    assertThat(
+            coordinatorClient.invokeSideEffects(
+                InvokeSideEffectsRequest.newBuilder().setLastIsCallback(true).build()))
+        .extracting { it.invokedTimes }
+        .isEqualTo(1)
+  }
+}