diff --git a/java/com/engflow/notificationqueue/Client.java b/java/com/engflow/notificationqueue/Client.java
index a0e5b99e..fdae5f52 100644
--- a/java/com/engflow/notificationqueue/Client.java
+++ b/java/com/engflow/notificationqueue/Client.java
@@ -22,6 +22,8 @@
 import io.grpc.netty.GrpcSslContexts;
 import io.grpc.netty.NegotiationType;
 import io.grpc.netty.NettyChannelBuilder;
+import io.grpc.stub.ClientCallStreamObserver;
+import io.grpc.stub.ClientResponseObserver;
 import io.grpc.stub.MetadataUtils;
 import io.grpc.stub.StreamObserver;
 import io.netty.handler.ssl.SslContextBuilder;
@@ -121,71 +123,79 @@ private static void pull(
     asyncStub = asyncStub.withInterceptors(MetadataUtils.newAttachHeadersInterceptor(header));
     final CountDownLatch finishLatch = new CountDownLatch(1);
     System.out.println("Listening for build events...");
-    StreamObserver<PullNotificationRequest> requestObserver =
-        asyncStub.pull(
-            new StreamObserver<PullNotificationResponse>() {
-              @Override
-              public void onNext(PullNotificationResponse response) {
-                Notification streamedNotification = response.getNotification().getNotification();
-                System.out.println("Notification: " + streamedNotification.toString());
-                try {
-                  /** Forward notification data to external server */
-                  forwardToBESStub(
-                      forwardChannel,
-                      streamedNotification.getId().toString(),
-                      streamedNotification.getPayload().toString());
-                } catch (Exception e) {
-                  System.err.println("Could not forward notification to external sever...");
-                }
-                Any notificationContent = streamedNotification.getPayload();
+    var observer =
+        new ClientResponseObserver<PullNotificationRequest, PullNotificationResponse>() {
+          private ClientCallStreamObserver<PullNotificationRequest> requestStream;
+
+          @Override
+          public void beforeStart(ClientCallStreamObserver<PullNotificationRequest> requestStream) {
+            this.requestStream = requestStream;
+          }
+
+          @Override
+          public void onNext(PullNotificationResponse response) {
+            if (!response.hasNotification()) {
+              return;
+            }
+            Notification streamedNotification = response.getNotification().getNotification();
+            System.out.println("Notification: " + streamedNotification.toString());
+            try {
+              /** Forward notification data to external server */
+              forwardToBESStub(
+                  forwardChannel,
+                  streamedNotification.getId().toString(),
+                  streamedNotification.getPayload().toString());
+            } catch (Exception e) {
+              System.err.println("Could not forward notification to external sever...");
+            }
+            Any notificationContent = streamedNotification.getPayload();
+            try {
+              BuildLifecycleEventNotification lifeCycleEvent =
+                  notificationContent.unpack(BuildLifecycleEventNotification.class);
+              /**
+               * Check if this is an invocation started event. Options are INVOCATION_STARTED and
+               * INVOCATION_FINISHED
+               */
+              if (lifeCycleEvent.getKindCase().name().equals("INVOCATION_STARTED")) {
+                String invocation = lifeCycleEvent.getInvocationStarted().getInvocationId();
                 try {
-                  BuildLifecycleEventNotification lifeCycleEvent =
-                      notificationContent.unpack(BuildLifecycleEventNotification.class);
                   /**
-                   * Check if this is an invocation started event. Options are INVOCATION_STARTED
-                   * and INVOCATION_FINISHED
+                   * Fetch the invocation using the grpc {@link EventStoreGrpc} stub using the
+                   * acquired invocation id
                    */
-                  if (lifeCycleEvent.getKindCase().name().equals("INVOCATION_STARTED")) {
-                    String invocation = lifeCycleEvent.getInvocationStarted().getInvocationId();
-                    try {
-                      /**
-                       * Fetch the invocation using the grpc {@link EventStoreGrpc} stub using the
-                       * acquired invocation id
-                       */
-                      getInvocations(channel, invocation, header, forwardChannel);
-                    } catch (InterruptedException e) {
-                      System.err.println("Could not get invocation with uuid " + invocation);
-                    }
-                  }
-
-                } catch (InvalidProtocolBufferException e) {
-                  throw new RuntimeException(e);
+                  getInvocations(channel, invocation, header, forwardChannel);
+                } catch (InterruptedException e) {
+                  System.err.println("Could not get invocation with uuid " + invocation);
                 }
               }
 
-              @Override
-              public void onError(Throwable t) {
-                System.err.println("Error on request: " + t.getMessage());
-                finishLatch.countDown();
-              }
+            } catch (InvalidProtocolBufferException e) {
+              throw new RuntimeException(e);
+            }
+            requestStream.onNext(
+                PullNotificationRequest.newBuilder()
+                    .addAcknowledgementTokens(response.getNotification().getToken())
+                    .build());
+          }
 
-              @Override
-              public void onCompleted() {
-                System.out.println("Finished pulling notifications");
-                finishLatch.countDown();
-              }
-            });
+          @Override
+          public void onError(Throwable t) {
+            System.err.println("Error on request: " + t.getMessage());
+            finishLatch.countDown();
+          }
 
-    try {
-      requestObserver.onNext(
-          PullNotificationRequest.newBuilder()
-              .setQueue(QueueId.newBuilder().setName(queueName).build())
-              .build());
-    } catch (RuntimeException e) {
-      // Cancel RPC
-      requestObserver.onError(e);
-      throw e;
-    }
+          @Override
+          public void onCompleted() {
+            System.out.println("Finished pulling notifications");
+            finishLatch.countDown();
+          }
+        };
+    asyncStub.pull(observer);
+
+    observer.requestStream.onNext(
+        PullNotificationRequest.newBuilder()
+            .setQueue(QueueId.newBuilder().setName(queueName).build())
+            .build());
 
     finishLatch.await();
   }