Reviewing

Author: Evanthx

core/src/main/java/io/temporal/samples/nexus_messaging/README.md

@@ -20,38 +20,41 @@ There are **two caller patterns** that share the same handler workflow (`Greetin
 
 ### Running
 
-Start a Temporal server and create namespaces/endpoint:
+Start a Temporal server:
 
 ```bash
 temporal server start-dev
+```
+Create the namespaces and Nexus endpoint:
 
-temporal operator namespace create --namespace nexus-sync-operations-handler-namespace
-temporal operator namespace create --namespace nexus-sync-operations-caller-namespace
+```bash
+temporal operator namespace create --namespace nexus-messaging-handler-namespace
+temporal operator namespace create --namespace nexus-messaging-caller-namespace
 
 temporal operator nexus endpoint create \
-  --name nexus-sync-operations-nexus-endpoint \
-  --target-namespace nexus-sync-operations-handler-namespace \
-  --target-task-queue nexus-sync-operations-handler-task-queue
+  --name nexus-messaging-nexus-endpoint \
+  --target-namespace nexus-messaging-handler-namespace \
+  --target-task-queue nexus-messaging-handler-task-queue
 ```
 
 In one terminal, start the handler worker (shared by both patterns):
 
 ```bash
-./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_sync_operations.handler.HandlerWorker
+./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_messaging.handler.HandlerWorker
 ```
 
 #### Entity pattern
 
-In a second terminal, run the caller worker:
+In the second terminal, run the caller worker:
 
 ```bash
-./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_sync_operations.caller.CallerWorker
+./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_messaging.caller.CallerWorker
 ```
 
-In a third terminal, start the caller workflow:
+In the third terminal, start the caller workflow:
 
 ```bash
-./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_sync_operations.caller.CallerStarter
+./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_messaging.caller.CallerStarter
 ```
 
 Expected output:
@@ -67,19 +70,19 @@ workflow approved
 In a second terminal, run the remote caller worker:
 
 ```bash
-./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_sync_operations.caller_remote.CallerRemoteWorker
+./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_messaging.caller_remote.CallerRemoteWorker
 ```
 
 In a third terminal, start the remote caller workflow:
 
 ```bash
-./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_sync_operations.caller_remote.CallerRemoteStarter
+./gradlew -q :core:execute -PmainClass=io.temporal.samples.nexus_messaging.caller_remote.CallerRemoteStarter
 ```
 
 Expected output:
 
 ```
-started remote greeting workflow: nexus-sync-operations-remote-greeting-workflow
+started remote greeting workflow: nexus-messaging-remote-greeting-workflow
 supported languages: [CHINESE, ENGLISH]
 language changed: ENGLISH -> ARABIC
 workflow approved

core/src/main/java/io/temporal/samples/nexus_messaging/caller/CallerStarter.java

@@ -20,7 +20,7 @@ public static void main(String[] args) {
         client.newWorkflowStub(
             CallerWorkflow.class,
             WorkflowOptions.newBuilder()
-                .setWorkflowId("nexus-sync-operations-caller-" + UUID.randomUUID())
+                .setWorkflowId("nexus-messaging-caller-" + UUID.randomUUID())
                 .setTaskQueue(CallerWorker.TASK_QUEUE)
                 .build());
 

core/src/main/java/io/temporal/samples/nexus_messaging/caller/CallerWorker.java

@@ -14,9 +14,9 @@
 public class CallerWorker {
   private static final Logger logger = LoggerFactory.getLogger(CallerWorker.class);
 
-  public static final String NAMESPACE = "nexus-sync-operations-caller-namespace";
-  public static final String TASK_QUEUE = "nexus-sync-operations-caller-task-queue";
-  static final String NEXUS_ENDPOINT = "nexus-sync-operations-nexus-endpoint";
+  public static final String NAMESPACE = "nexus-messaging-caller-namespace";
+  public static final String TASK_QUEUE = "nexus-messaging-caller-task-queue";
+  static final String NEXUS_ENDPOINT = "nexus-messaging-nexus-endpoint";
 
   public static void main(String[] args) throws InterruptedException {
     WorkflowServiceStubs service = WorkflowServiceStubs.newLocalServiceStubs();
@@ -29,6 +29,7 @@ public static void main(String[] args) throws InterruptedException {
     worker.registerWorkflowImplementationTypes(
         WorkflowImplementationOptions.newBuilder()
             .setNexusServiceOptions(
+                // The key must match the @Service-annotated interface name.
                 Collections.singletonMap(
                     "NexusGreetingService",
                     NexusServiceOptions.newBuilder().setEndpoint(NEXUS_ENDPOINT).build()))

core/src/main/java/io/temporal/samples/nexus_messaging/caller/CallerWorkflowImpl.java

@@ -1,6 +1,7 @@
 package io.temporal.samples.nexus_messaging.caller;
 
 import io.temporal.failure.ApplicationFailure;
+import io.temporal.samples.nexus_messaging.caller_remote.CallerRemoteWorkflowImpl;
 import io.temporal.samples.nexus_messaging.service.Language;
 import io.temporal.samples.nexus_messaging.service.NexusGreetingService;
 import io.temporal.workflow.NexusOperationOptions;
@@ -9,9 +10,13 @@
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class CallerWorkflowImpl implements CallerWorkflow {
 
+  private static final Logger logger = LoggerFactory.getLogger(CallerRemoteWorkflowImpl.class);
+
   // The endpoint is configured at the worker level in CallerWorker; only operation options are
   // set here.
   NexusGreetingService greetingService =
@@ -36,6 +41,7 @@ public List<String> run() {
     // 👉 Call a Nexus operation backed by an update against the entity workflow.
     Language previousLanguage =
         greetingService.setLanguage(new NexusGreetingService.SetLanguageInput(Language.ARABIC));
+    logger.info("Language changed from {} to {}", previousLanguage, Language.ARABIC);
 
     // 👉 Call a Nexus operation backed by a query to confirm the language change.
     Language currentLanguage =

core/src/main/java/io/temporal/samples/nexus_messaging/caller_remote/CallerRemoteStarter.java

@@ -20,7 +20,7 @@ public static void main(String[] args) {
         client.newWorkflowStub(
             CallerRemoteWorkflow.class,
             WorkflowOptions.newBuilder()
-                .setWorkflowId("nexus-sync-operations-remote-caller-" + UUID.randomUUID())
+                .setWorkflowId("nexus-messaging-remote-caller-" + UUID.randomUUID())
                 .setTaskQueue(CallerRemoteWorker.TASK_QUEUE)
                 .build());
 

core/src/main/java/io/temporal/samples/nexus_messaging/caller_remote/CallerRemoteWorker.java

@@ -14,9 +14,9 @@
 public class CallerRemoteWorker {
   private static final Logger logger = LoggerFactory.getLogger(CallerRemoteWorker.class);
 
-  public static final String NAMESPACE = "nexus-sync-operations-caller-namespace";
-  public static final String TASK_QUEUE = "nexus-sync-operations-caller-remote-task-queue";
-  static final String NEXUS_ENDPOINT = "nexus-sync-operations-nexus-endpoint";
+  public static final String NAMESPACE = "nexus-messaging-caller-namespace";
+  public static final String TASK_QUEUE = "nexus-messaging-caller-remote-task-queue";
+  static final String NEXUS_ENDPOINT = "nexus-messaging-nexus-endpoint";
 
   public static void main(String[] args) throws InterruptedException {
     WorkflowServiceStubs service = WorkflowServiceStubs.newLocalServiceStubs();
@@ -29,6 +29,7 @@ public static void main(String[] args) throws InterruptedException {
     worker.registerWorkflowImplementationTypes(
         WorkflowImplementationOptions.newBuilder()
             .setNexusServiceOptions(
+                // The key must match the @Service-annotated interface name.
                 Collections.singletonMap(
                     "NexusRemoteGreetingService",
                     NexusServiceOptions.newBuilder().setEndpoint(NEXUS_ENDPOINT).build()))

core/src/main/java/io/temporal/samples/nexus_messaging/caller_remote/CallerRemoteWorkflowImpl.java

@@ -17,7 +17,7 @@ public class CallerRemoteWorkflowImpl implements CallerRemoteWorkflow {
 
   private static final Logger logger = LoggerFactory.getLogger(CallerRemoteWorkflowImpl.class);
 
-  private static final String REMOTE_WORKFLOW_ID = "nexus-sync-operations-remote-greeting-workflow";
+  private static final String REMOTE_WORKFLOW_ID = "nexus-messaging-remote-greeting-workflow";
 
   NexusRemoteGreetingService greetingRemoteService =
       Workflow.newNexusServiceStub(
@@ -33,7 +33,9 @@ public class CallerRemoteWorkflowImpl implements CallerRemoteWorkflow {
   public List<String> run() {
     List<String> log = new ArrayList<>();
 
-    // Start a new GreetingWorkflow on the handler side via Nexus.
+    // 👉 Async Nexus operation — starts a workflow on the handler and returns a handle.
+    // Unlike the sync operations below (getLanguages, setLanguage, etc.), this does not block
+    // until the workflow completes. It is backed by WorkflowRunOperation on the handler side.
     NexusOperationHandle<String> handle =
         Workflow.startNexusOperation(
             greetingRemoteService::runFromRemote,
@@ -43,6 +45,8 @@ public List<String> run() {
     log.add("started remote greeting workflow: " + REMOTE_WORKFLOW_ID);
 
     // Query the remote workflow for supported languages.
+    // Output types (e.g. GetLanguagesOutput) are defined on NexusGreetingService and shared by
+    // both service interfaces.
     NexusGreetingService.GetLanguagesOutput languagesOutput =
         greetingRemoteService.getLanguages(
             new NexusRemoteGreetingService.GetLanguagesInput(false, REMOTE_WORKFLOW_ID));
@@ -52,7 +56,7 @@ public List<String> run() {
     Language previousLanguage =
         greetingRemoteService.setLanguage(
             new NexusRemoteGreetingService.SetLanguageInput(Language.ARABIC, REMOTE_WORKFLOW_ID));
-    logger.info("Language changed from {}", previousLanguage);
+    logger.info("Language changed from {} to {}", previousLanguage, Language.ARABIC);
 
     // Confirm the change by querying.
     Language currentLanguage =

core/src/main/java/io/temporal/samples/nexus_messaging/handler/GreetingWorkflowImpl.java

@@ -22,7 +22,7 @@ public class GreetingWorkflowImpl implements GreetingWorkflow {
   private final Map<Language, String> greetings = new EnumMap<>(Language.class);
   private Language language = Language.ENGLISH;
 
-  private static final Logger logger = LoggerFactory.getLogger(HandlerWorker.class);
+  private static final Logger logger = LoggerFactory.getLogger(GreetingWorkflowImpl.class);
 
   // Used to serialize concurrent setLanguageUsingActivity calls so that only one activity runs at
   // a time per update handler execution.

core/src/main/java/io/temporal/samples/nexus_messaging/handler/HandlerWorker.java

@@ -13,9 +13,9 @@
 public class HandlerWorker {
   private static final Logger logger = LoggerFactory.getLogger(HandlerWorker.class);
 
-  public static final String NAMESPACE = "nexus-sync-operations-handler-namespace";
-  public static final String TASK_QUEUE = "nexus-sync-operations-handler-task-queue";
-  static final String WORKFLOW_ID = "nexus-sync-operations-greeting-workflow";
+  public static final String NAMESPACE = "nexus-messaging-handler-namespace";
+  public static final String TASK_QUEUE = "nexus-messaging-handler-task-queue";
+  static final String WORKFLOW_ID = "nexus-messaging-greeting-workflow";
 
   public static void main(String[] args) throws InterruptedException {
     WorkflowServiceStubs service = WorkflowServiceStubs.newLocalServiceStubs();

core/src/main/java/io/temporal/samples/nexus_messaging/handler/NexusGreetingServiceImpl.java

@@ -53,9 +53,11 @@ public OperationHandler<NexusGreetingService.GetLanguageInput, Language> getLang
         });
   }
 
-  // 👉 Backed by an update against the long-running entity workflow. Although updates can run for
-  // an arbitrarily long time, when exposed via a sync Nexus operation the update should complete
-  // quickly (sync operations must finish in under 10s).
+  // 👉 Backed by an update against the long-running entity workflow. Routes to
+  // setLanguageUsingActivity (not setLanguage) so that new languages not already in the greetings
+  // map can be fetched via an activity. Although updates can run for an arbitrarily long time, when
+  // exposed via a sync Nexus operation the update should complete quickly (sync operations must
+  // finish in under 10s).
   @OperationImpl
   public OperationHandler<NexusGreetingService.SetLanguageInput, Language> setLanguage() {
     return OperationHandler.sync(