Add a Nexus early return sample

build.gradle

@@ -28,7 +28,7 @@ subprojects {
     ext {
         otelVersion = '1.30.1'
         otelVersionAlpha = "${otelVersion}-alpha"
-        javaSDKVersion = '1.28.1'
+        javaSDKVersion = '1.28.4'
         camelVersion = '3.22.1'
         jarVersion = '1.0.0'
     }

core/src/main/java/io/temporal/samples/nexusEarlyReturn/README.MD

@@ -0,0 +1,38 @@
+# Nexus Early Return
+
+This sample demonstrates the early return pattern with Nexus. 
+
+For more details on the early return pattern see the [Early Return Sample](../earlyreturn/README.md)
+
+To run this sample, set up your environment following the instructions in the main [Nexus Sample](../nexus/README.md).
+
+In separate terminal windows:
+
+### Nexus handler worker
+
+```
+./gradlew -q execute -PmainClass=io.temporal.samples.nexusEarlyReturn.handler.HandlerWorker \
+    --args="-target-host localhost:7233 -namespace my-target-namespace"
+```
+
+### Nexus caller worker
+
+```
+./gradlew -q execute -PmainClass=io.temporal.samples.nexusEarlyReturn.caller.CallerWorker \
+    --args="-target-host localhost:7233 -namespace my-caller-namespace"
+```
+
+### Start caller workflow
+
+```
+./gradlew -q execute -PmainClass=io.temporal.samples.nexusEarlyReturn.caller.CallerStarter \
+    --args="-target-host localhost:7233 -namespace my-caller-namespace"
+```
+
+### Output
+
+which should result in:
+```
+10:52:08.542 { } [main] INFO  i.t.s.n.caller.CallerStarter - Started TransferWorkflow workflowId: 1526a62a-cc76-49a9-bc10-b91d67b4f0e8 runId: 01974b85-7b59-76e5-80aa-3ab0dfb983ef 
+10:52:12.084 { } [main] INFO  i.t.s.n.caller.CallerStarter - Workflow result: Transaction completed successfully. 
+```

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

@@ -0,0 +1,51 @@
+/*
+ *  Copyright (c) 2020 Temporal Technologies, Inc. All Rights Reserved
+ *
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file is distributed on
+ *  an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ *  express or implied. See the License for the specific language governing
+ *  permissions and limitations under the License.
+ */
+
+package io.temporal.samples.nexusEarlyReturn.caller;
+
+import io.temporal.api.common.v1.WorkflowExecution;
+import io.temporal.client.WorkflowClient;
+import io.temporal.client.WorkflowOptions;
+import io.temporal.samples.earlyreturn.TransactionRequest;
+import io.temporal.samples.nexusEarlyReturn.options.ClientOptions;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class CallerStarter {
+  private static final Logger logger = LoggerFactory.getLogger(CallerStarter.class);
+
+  public static void main(String[] args) {
+    WorkflowClient client = ClientOptions.getWorkflowClient(args);
+
+    WorkflowOptions workflowOptions =
+        WorkflowOptions.newBuilder().setTaskQueue(CallerWorker.DEFAULT_TASK_QUEUE_NAME).build();
+    TransferWorkflow transferWorkflow =
+        client.newWorkflowStub(TransferWorkflow.class, workflowOptions);
+    WorkflowExecution execution =
+        WorkflowClient.start(
+            transferWorkflow::transfer, new TransactionRequest("source", "target", 100));
+    logger.info(
+        "Started TransferWorkflow workflowId: {} runId: {}",
+        execution.getWorkflowId(),
+        execution.getRunId());
+    logger.info(
+        "Workflow result: {}",
+        transferWorkflow.transfer(new TransactionRequest("source", "target", 100)));
+  }
+}

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

@@ -0,0 +1,50 @@
+/*
+ *  Copyright (c) 2020 Temporal Technologies, Inc. All Rights Reserved
+ *
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file is distributed on
+ *  an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ *  express or implied. See the License for the specific language governing
+ *  permissions and limitations under the License.
+ */
+
+package io.temporal.samples.nexusEarlyReturn.caller;
+
+import io.temporal.client.WorkflowClient;
+import io.temporal.samples.nexusEarlyReturn.options.ClientOptions;
+import io.temporal.worker.Worker;
+import io.temporal.worker.WorkerFactory;
+import io.temporal.worker.WorkflowImplementationOptions;
+import io.temporal.workflow.NexusServiceOptions;
+import java.util.Collections;
+
+public class CallerWorker {
+  public static final String DEFAULT_TASK_QUEUE_NAME = "my-caller-workflow-task-queue";
+
+  public static void main(String[] args) {
+    WorkflowClient client = ClientOptions.getWorkflowClient(args);
+
+    WorkerFactory factory = WorkerFactory.newInstance(client);
+
+    Worker worker = factory.newWorker(DEFAULT_TASK_QUEUE_NAME);
+    worker.registerWorkflowImplementationTypes(
+        WorkflowImplementationOptions.newBuilder()
+            .setNexusServiceOptions(
+                Collections.singletonMap(
+                    "TransactionService",
+                    NexusServiceOptions.newBuilder().setEndpoint("my-nexus-endpoint-name").build()))
+            .build(),
+        TransferWorkflowImpl.class);
+
+    factory.start();
+  }
+}

core/src/main/java/io/temporal/samples/nexusEarlyReturn/caller/TransferWorkflow.java

@@ -0,0 +1,30 @@
+/*
+ *  Copyright (c) 2020 Temporal Technologies, Inc. All Rights Reserved
+ *
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file is distributed on
+ *  an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ *  express or implied. See the License for the specific language governing
+ *  permissions and limitations under the License.
+ */
+
+package io.temporal.samples.nexusEarlyReturn.caller;
+
+import io.temporal.samples.earlyreturn.TransactionRequest;
+import io.temporal.workflow.WorkflowInterface;
+import io.temporal.workflow.WorkflowMethod;
+
+@WorkflowInterface
+public interface TransferWorkflow {
+  @WorkflowMethod
+  String transfer(TransactionRequest message);
+}

core/src/main/java/io/temporal/samples/nexusEarlyReturn/caller/TransferWorkflowImpl.java

@@ -0,0 +1,80 @@
+/*
+ *  Copyright (c) 2020 Temporal Technologies, Inc. All Rights Reserved
+ *
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file is distributed on
+ *  an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ *  express or implied. See the License for the specific language governing
+ *  permissions and limitations under the License.
+ */
+
+package io.temporal.samples.nexusEarlyReturn.caller;
+
+import io.temporal.failure.ApplicationFailure;
+import io.temporal.failure.NexusOperationFailure;
+import io.temporal.samples.earlyreturn.TransactionRequest;
+import io.temporal.samples.earlyreturn.TxResult;
+import io.temporal.samples.nexusEarlyReturn.service.TransactionService;
+import io.temporal.workflow.NexusOperationOptions;
+import io.temporal.workflow.NexusServiceOptions;
+import io.temporal.workflow.Workflow;
+import java.time.Duration;
+
+/**
+ * TransferWorkflowImpl starts a transfer and waits for it to complete (if the transaction is
+ * successful or not).
+ */
+public class TransferWorkflowImpl implements TransferWorkflow {
+  TransactionService transactionService =
+      Workflow.newNexusServiceStub(
+          TransactionService.class,
+          NexusServiceOptions.newBuilder()
+              .setOperationOptions(
+                  NexusOperationOptions.newBuilder()
+                      .setScheduleToCloseTimeout(Duration.ofSeconds(10))
+                      .build())
+              .build());
+
+  @Override
+  public String transfer(TransactionRequest request) {
+    try {
+      // Start a transaction using the TransactionService Nexus service. Once the transaction is
+      // started, it will run asynchronously, and we can check the result later.
+      TransactionService.StartTransactionResponse r =
+          transactionService.startTransaction(
+              new TransactionService.StartTransactionRequest(request));
+      // Note: this random sleep is to simulate some processing time before checking the result.
+      // Depending on how long the sleep is, the transaction may complete before we check the
+      // result.
+      Workflow.sleep(Duration.ofMillis(Workflow.newRandom().nextInt(100)));
+      TxResult result =
+          transactionService.getTransactionResult(
+              new TransactionService.GetTransactionResultRequest(r.getTransactionToken()));
+      return result.getStatus();
+    } catch (NexusOperationFailure of) {
+      // If the operation failed, we check if it was due to a transaction failure.
+      if (of.getCause() instanceof ApplicationFailure) {
+        ApplicationFailure af = (ApplicationFailure) of.getCause();
+        if (af.getType().equals("TransactionFailed")) {
+          // If the transaction failed, we can retrieve the transaction token from the details
+          // and use it to wait for the transaction to cancel.
+          String transactionToken = af.getDetails().get(String.class);
+          TxResult result =
+              transactionService.getTransactionResult(
+                  new TransactionService.GetTransactionResultRequest(transactionToken));
+          return result.getStatus();
+        }
+      }
+      throw of;
+    }
+  }
+}

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

@@ -0,0 +1,44 @@
+/*
+ *  Copyright (c) 2020 Temporal Technologies, Inc. All Rights Reserved
+ *
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file is distributed on
+ *  an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ *  express or implied. See the License for the specific language governing
+ *  permissions and limitations under the License.
+ */
+
+package io.temporal.samples.nexusEarlyReturn.handler;
+
+import io.temporal.client.WorkflowClient;
+import io.temporal.samples.earlyreturn.TransactionActivitiesImpl;
+import io.temporal.samples.earlyreturn.TransactionWorkflowImpl;
+import io.temporal.samples.nexusEarlyReturn.options.ClientOptions;
+import io.temporal.worker.Worker;
+import io.temporal.worker.WorkerFactory;
+
+public class HandlerWorker {
+  public static final String DEFAULT_TASK_QUEUE_NAME = "my-handler-task-queue";
+
+  public static void main(String[] args) {
+    WorkflowClient client = ClientOptions.getWorkflowClient(args);
+
+    WorkerFactory factory = WorkerFactory.newInstance(client);
+
+    Worker worker = factory.newWorker(DEFAULT_TASK_QUEUE_NAME);
+    worker.registerWorkflowImplementationTypes(TransactionWorkflowImpl.class);
+    worker.registerActivitiesImplementations(new TransactionActivitiesImpl());
+    worker.registerNexusServiceImplementation(new TransactionServiceImpl());
+
+    factory.start();
+  }
+}