task interaction

Author: antmendoza

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

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+# Demo tasks interaction
+
+This example demonstrate a generic implementation for tasks interaction in Temporal.
+
+The basic implementation consist on three parts:
+- One activity (or local activity) that send the request (create a task).
+- Block the workflow execution `Workflow.await` awaiting a Signal.
+- The workflow will eventually receive a signal that unblocks it.
+
+Additionally, the example allows to track task state (PENDING, STARTED, COMPLETED...) and 
+list open task.
+
+> If the client can not send a Signal to the workflow execution, steps 2 and 3 can be replaced by an activity
+that polls using one of [these three strategies](../polling).
+
+## Run the sample
+
+- Start the worker
+
+```bash
+./gradlew -q execute -PmainClass=io.temporal.samples.taskinteraction.worker.Worker
+```
+
+- Schedule workflow execution 
+
+```bash
+./gradlew -q execute -PmainClass=io.temporal.samples.taskinteraction.client.StartWorkflow
+```
+
+- List task
+
+This process will query the workflow execution every 10 seconds, and print open tasks (state != COMPLETED).
+```bash
+./gradlew -q execute -PmainClass=io.temporal.samples.taskinteraction.client.ListOpenTasks
+
+
+
+```
+- Update task
+
+Update one of the open task to the next state (PENDING -> STARTED -> COMPLETED)
+```bash
+./gradlew -q execute -PmainClass=io.temporal.samples.taskinteraction.client.ListOpenTasks
+```

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

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+/*
+ *  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 com.fasterxml.jackson.annotation.JsonIgnore;
+
+public class Task {
+
+  private String token;
+  private Object data;
+  private STATE state;
+
+  public Task() {}
+
+  public Task(String token) {
+    this.token = token;
+    this.state = STATE.PENDING;
+  }
+
+  public String getToken() {
+    return token;
+  }
+
+  public void setData(Object data) {
+    this.data = data;
+  }
+
+  public <T> T result(Class<T> tClass) {
+    return (T) data;
+  }
+
+  public void setState(STATE state) {
+    this.state = state;
+  }
+
+  public STATE getState() {
+    return state;
+  }
+
+  @JsonIgnore
+  public boolean isCompleted() {
+    return STATE.COMPLETED == this.state;
+  }
+
+  @Override
+  public String toString() {
+    return "Task{" + "token='" + token + '\'' + ", data=" + data + ", state=" + state + '}';
+  }
+
+  public enum STATE {
+    PENDING,
+    STARTED,
+    COMPLETED
+  }
+}

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

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+/*
+ *  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.ActivityInterface;
+
+@ActivityInterface
+public interface TaskActivity {
+
+  String createTask(String task);
+}

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

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+/*
+ *  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;
+
+public class TaskActivityImpl implements TaskActivity {
+  @Override
+  public String createTask(String task) {
+
+    // Simulating delay in task creation
+    try {
+      Thread.sleep(500);
+    } catch (InterruptedException e) {
+      throw new RuntimeException(e);
+    }
+
+    return "activity created";
+  }
+}

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

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+/*
+ *  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.QueryMethod;
+import io.temporal.workflow.SignalMethod;
+import java.util.List;
+
+/** Interface used to dynamically register signal and query handlers from the interceptor. */
+public interface TaskClient {
+
+  @SignalMethod
+  void updateTask(TaskService.TaskRequest task);
+
+  @QueryMethod
+  List<Task> getOpenTasks();
+}

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

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+/*
+ *  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 com.fasterxml.jackson.annotation.JsonIgnore;
+import io.temporal.workflow.CompletablePromise;
+import io.temporal.workflow.Promise;
+import io.temporal.workflow.Workflow;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import org.slf4j.Logger;
+
+public class TaskService<R> {
+
+  private final Map<String, Task> tasks = Collections.synchronizedMap(new HashMap<>());
+  private final Map<String, CompletablePromise<R>> pendingPromises =
+      Collections.synchronizedMap(new HashMap<>());
+
+  // Exposes signal and query methods that
+  // allow us to interact with the workflow execution
+  private final TaskClient listener =
+      new TaskClient() {
+
+        @Override
+        public void updateTask(TaskRequest taskRequest) {
+
+          final String token = taskRequest.getToken();
+          final String data = taskRequest.getData();
+          tasks.get(token).setData(data);
+
+          final Task t = tasks.get(token);
+
+          t.setState(taskRequest.state);
+          tasks.put(t.getToken(), t);
+
+          logger.info("Task updated: " + t);
+
+          if (taskRequest.state == Task.STATE.COMPLETED) {
+            final CompletablePromise<R> completablePromise = pendingPromises.get(token);
+            completablePromise.complete((R) data);
+          }
+        }
+
+        @Override
+        public List<Task> getOpenTasks() {
+          return tasks.values().stream().filter(t -> !t.isCompleted()).collect(Collectors.toList());
+        }
+      };
+
+  public TaskService() {
+    Workflow.registerListener(listener);
+  }
+
+  private final Logger logger = Workflow.getLogger(TaskService.class);
+
+  public R executeTask(Callback<R> callback, String token) {
+    return executeTaskAsync(callback, token).get();
+  }
+
+  public Promise<R> executeTaskAsync(Callback<R> callback, String token) {
+
+    final Task task = new Task(token);
+    logger.info("Before creating task : " + task);
+    tasks.put(token, task);
+    callback.execute();
+    logger.info("Task created: " + task);
+
+    final CompletablePromise<R> promise = Workflow.newPromise();
+    pendingPromises.put(token, promise);
+
+    return promise;
+  }
+
+  public List<Task> getOpenTasks() {
+    return listener.getOpenTasks();
+  }
+
+  public interface Callback<T> {
+    T execute();
+  }
+
+  public static class TaskRequest {
+
+    private Task.STATE state;
+    private String data;
+    private String token;
+
+    public TaskRequest() {}
+
+    public TaskRequest(Task.STATE state, String data, String token) {
+      this.state = state;
+      this.data = data;
+      this.token = token;
+    }
+
+    @JsonIgnore
+    public boolean isCompleted() {
+      return this.state == Task.STATE.COMPLETED;
+    }
+
+    public String getToken() {
+      return token;
+    }
+
+    public String getData() {
+      return data;
+    }
+  }
+}

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

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+/*
+ *  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.WorkflowInterface;
+import io.temporal.workflow.WorkflowMethod;
+
+@WorkflowInterface
+public interface TaskWorkflow {
+
+  @WorkflowMethod
+  void execute();
+}