Example for tasks interaction

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

@@ -0,0 +1,47 @@
+# Demo tasks interaction
+
+This example demonstrates a generic implementation for "User Tasks" interaction with Temporal, 
+which can be easily implemented as follows: 
+- The main workflow [WorkflowWithTasks](./WorkflowWithTasks.java) have an activity (or local activity) that send the request to an external service. 
+The _external service_, for this example, is another workflow ([WorkflowTaskManager](WorkflowTaskManager.java)), 
+that takes care of the task life-cicle.
+- The main workflow waits to receive a Signal. 
+- The _external service_ signal back the main 
+workflow to unblock it.
+
+The two first steps mentioned above are encapsulated in the class [TaskService.java](./TaskService.java), to make it easily reusable.
+
+## Run the sample
+
+- Schedule the main workflow execution ([WorkflowWithTasks](./WorkflowWithTasks.java)), the one that contains the _User Tasks_ 
+
+```bash
+./gradlew -q execute -PmainClass=io.temporal.samples.taskinteraction.client.StartWorkflow
+```
+
+- Open other terminal and start the Worker
+
+```bash
+./gradlew -q execute -PmainClass=io.temporal.samples.taskinteraction.worker.Worker
+```
+
+You will notice, from the worker logs, that it start the main workflow and execute two activities, the
+two activities register two tasks to the external service ([WorkflowTaskManagerImpl.java](WorkflowTaskManagerImpl.java))
+
+```
+07:19:39.528 {WorkflowWithTasks1714454371179 } [workflow[WorkflowWithTasks1714454371179]-1] INFO  i.t.s.taskinteraction.TaskService - Before creating task : Task{token='WorkflowWithTasks1714454371179_1', title=TaskTitle{value='TODO 1'}} 
+07:19:39.563 {WorkflowWithTasks1714454371179 } [workflow[WorkflowWithTasks1714454371179]-2] INFO  i.t.s.taskinteraction.TaskService - Before creating task : Task{token='WorkflowWithTasks1714454371179_2', title=TaskTitle{value='TODO 2'}} 
+07:19:39.683 {WorkflowWithTasks1714454371179 } [workflow[WorkflowWithTasks1714454371179]-1] INFO  i.t.s.taskinteraction.TaskService - Task created: Task{token='WorkflowWithTasks1714454371179_1', title=TaskTitle{value='TODO 1'}} 
+07:19:39.684 {WorkflowWithTasks1714454371179 } [workflow[WorkflowWithTasks1714454371179]-2] INFO  i.t.s.taskinteraction.TaskService - Task created: Task{token='WorkflowWithTasks1714454371179_2', title=TaskTit
+```
+
+- Now, we can start completing the tasks using the helper class [CompleteTask.java](./client/CompleteTask.java)
+
+```bash
+./gradlew -q execute -PmainClass=io.temporal.samples.taskinteraction.client.CompleteTask
+```
+You can see from the implementation that [WorkflowWithTasksImpl](./WorkflowWithTasksImpl.java) has three task.
+- two in parallel using `Async.procedure`,
+- one blocking task at the end.
+
+This class needs to be run three times. After the three task are completed the main workflow completes.

core/src/main/java/io/temporal/samples/taskinteraction/Task.java

@@ -0,0 +1,98 @@
+/*
+ *  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.taskinteraction;
+
+import java.util.Objects;
+
+public class Task {
+
+  private String token;
+  private TaskTitle title;
+
+  public Task() {}
+
+  public Task(String token, TaskTitle title) {
+    this.token = token;
+    this.title = title;
+  }
+
+  public String getToken() {
+    return token;
+  }
+
+  public TaskTitle getTitle() {
+    return title;
+  }
+
+  @Override
+  public boolean equals(final Object o) {
+    if (this == o) return true;
+    if (!(o instanceof Task)) return false;
+    final Task task = (Task) o;
+    return Objects.equals(token, task.token) && Objects.equals(title, task.title);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(token, title);
+  }
+
+  @Override
+  public String toString() {
+    return "Task{" + "token='" + token + '\'' + ", title=" + title + '}';
+  }
+
+  public static class TaskTitle {
+    private String value;
+
+    public TaskTitle() {}
+
+    public TaskTitle(final String value) {
+
+      this.value = value;
+    }
+
+    public String getValue() {
+      return value;
+    }
+
+    public void setValue(final String value) {
+      this.value = value;
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+      if (this == o) return true;
+      if (!(o instanceof TaskTitle)) return false;
+      final TaskTitle taskTitle = (TaskTitle) o;
+      return Objects.equals(value, taskTitle.value);
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(value);
+    }
+
+    @Override
+    public String toString() {
+      return "TaskTitle{" + "value='" + value + '\'' + '}';
+    }
+  }
+}

core/src/main/java/io/temporal/samples/taskinteraction/TaskClient.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.taskinteraction;
+
+import io.temporal.workflow.SignalMethod;
+import io.temporal.workflow.WorkflowInterface;
+
+@WorkflowInterface
+public interface TaskClient {
+
+  @SignalMethod
+  void completeTaskByToken(String taskToken);
+}

core/src/main/java/io/temporal/samples/taskinteraction/TaskService.java

@@ -0,0 +1,91 @@
+/*
+ *  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.taskinteraction;
+
+import io.temporal.activity.ActivityOptions;
+import io.temporal.samples.taskinteraction.activity.ActivityTask;
+import io.temporal.workflow.CompletablePromise;
+import io.temporal.workflow.Workflow;
+import java.time.Duration;
+import java.util.HashMap;
+import java.util.Map;
+import org.slf4j.Logger;
+
+/**
+ * This class responsibility is to register the task in the external system and waits for the
+ * external system to signal back.
+ */
+public class TaskService<R> {
+
+  private final ActivityTask activity =
+      Workflow.newActivityStub(
+          ActivityTask.class,
+          ActivityOptions.newBuilder().setStartToCloseTimeout(Duration.ofSeconds(5)).build());
+
+  private TaskManager tasksManager = new TaskManager();
+
+  private final Logger logger = Workflow.getLogger(TaskService.class);
+
+  public TaskService() {
+
+    // This listener exposes a signal method that clients use to notify the task has been completed
+    Workflow.registerListener(
+        new TaskClient() {
+          @Override
+          public void completeTaskByToken(final String taskToken) {
+            logger.info("Completing task with token: " + taskToken);
+            tasksManager.completeTask(taskToken);
+          }
+        });
+  }
+
+  public void executeTask(Task task) {
+
+    logger.info("Before creating task : " + task);
+
+    // Activity implementation is responsible for registering the task to the external service
+    // (which is responsible for managing the task life-cycle)
+    activity.createTask(task);
+
+    logger.info("Task created: " + task);
+
+    tasksManager.waitForTaskCompletion(task);
+
+    logger.info("Task completed: " + task);
+  }
+
+  private class TaskManager {
+
+    private final Map<String, CompletablePromise<R>> tasks = new HashMap<>();
+
+    public void waitForTaskCompletion(final Task task) {
+      final CompletablePromise<R> promise = Workflow.newPromise();
+      tasks.put(task.getToken(), promise);
+      // Wait promise to complete
+      promise.get();
+    }
+
+    public void completeTask(final String taskToken) {
+
+      final CompletablePromise<R> completablePromise = tasks.get(taskToken);
+      completablePromise.complete(null);
+    }
+  }
+}

core/src/main/java/io/temporal/samples/taskinteraction/WorkflowTaskManager.java

@@ -0,0 +1,41 @@
+/*
+ *  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.taskinteraction;
+
+import io.temporal.workflow.*;
+import java.util.List;
+
+@WorkflowInterface
+public interface WorkflowTaskManager {
+
+  String WORKFLOW_ID = WorkflowTaskManager.class.getSimpleName();
+
+  @WorkflowMethod
+  void execute(final WorkflowTaskManagerImpl.PendingTasks pendingTasks);
+
+  @UpdateMethod
+  void createTask(Task task);
+
+  @UpdateMethod
+  void completeTaskByToken(String taskToken);
+
+  @QueryMethod
+  List<Task> getPendingTask();
+}