HelloCron.java

/*
 *  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.hello;

import io.temporal.activity.Activity;
import io.temporal.activity.ActivityInterface;
import io.temporal.activity.ActivityOptions;
import io.temporal.api.common.v1.WorkflowExecution;
import io.temporal.client.WorkflowClient;
import io.temporal.client.WorkflowExecutionAlreadyStarted;
import io.temporal.client.WorkflowOptions;
import io.temporal.serviceclient.WorkflowServiceStubs;
import io.temporal.worker.Worker;
import io.temporal.worker.WorkerFactory;
import io.temporal.workflow.Workflow;
import io.temporal.workflow.WorkflowInterface;
import io.temporal.workflow.WorkflowMethod;
import java.time.Duration;

/**
 * Sample Temporal workflow that demonstrates periodic workflow execution using a cron. Note that
 * the periodic execution is based on a fixed delay (provided by the cron definition). To learn
 * about periodic execution with a dynamic delay checkout the {@link HelloPeriodic} example.
 */
public class HelloCron {

  // Define the task queue name
  static final String TASK_QUEUE = "HelloCronTaskQueue";

  // Define the workflow unique id
  static final String WORKFLOW_ID = "HelloCronWorkflow";

  /**
   * The Workflow Definition's Interface must contain one method annotated with @WorkflowMethod.
   *
   * <p>Workflow Definitions should not contain any heavyweight computations, non-deterministic
   * code, network calls, database operations, etc. Those things should be handled by the
   * Activities.
   *
   * @see io.temporal.workflow.WorkflowInterface
   * @see io.temporal.workflow.WorkflowMethod
   */
  @WorkflowInterface
  public interface GreetingWorkflow {

    /**
     * This is the method that is executed when the Workflow Execution is started. The Workflow
     * Execution completes when this method finishes execution.
     */
    @WorkflowMethod
    void greet(String name);
  }

  /**
   * This is the Activity Definition's Interface. Activities are building blocks of any Temporal
   * Workflow and contain any business logic that could perform long running computation, network
   * calls, etc.
   *
   * <p>Annotating Activity Definition methods with @ActivityMethod is optional.
   *
   * @see io.temporal.activity.ActivityInterface
   * @see io.temporal.activity.ActivityMethod
   */
  @ActivityInterface
  public interface GreetingActivities {

    // Define your activity method which can be called during workflow execution
    void greet(String greeting);
  }

  // Define the workflow implementation which implements the greet workflow method.
  public static class GreetingWorkflowImpl implements GreetingWorkflow {

    /**
     * Define the GreetingActivities stub. Activity stubs are proxies for activity invocations that
     * are executed outside of the workflow thread on the activity worker, that can be on a
     * different host. Temporal is going to dispatch the activity results back to the workflow and
     * unblock the stub as soon as activity is completed on the activity worker.
     *
     * <p>In the {@link ActivityOptions} definition the "setStartToCloseTimeout" option sets the
     * maximum time of a single Activity execution attempt. For this example it is set to 10
     * seconds.
     */
    private final GreetingActivities activities =
        Workflow.newActivityStub(
            GreetingActivities.class,
            ActivityOptions.newBuilder().setStartToCloseTimeout(Duration.ofSeconds(10)).build());

    @Override
    public void greet(String name) {
      activities.greet("Hello " + name + "!");
    }
  }

  /**
   * Implementation of the workflow activity interface. It overwrites the defined greet activity
   * method.
   */
  static class GreetingActivitiesImpl implements GreetingActivities {
    @Override
    public void greet(String greeting) {
      System.out.println(
          "From " + Activity.getExecutionContext().getInfo().getWorkflowId() + ": " + greeting);
    }
  }

  /**
   * With the Workflow and Activities defined, we can now start execution. The main method starts
   * the worker and then the workflow.
   */
  public static void main(String[] args) {

    // Get a Workflow service stub.
    WorkflowServiceStubs service = WorkflowServiceStubs.newLocalServiceStubs();

    /*
     * Get a Workflow service client which can be used to start, Signal, and Query Workflow Executions.
     */
    WorkflowClient client = WorkflowClient.newInstance(service);

    /*
     * Define the workflow factory. It is used to create workflow workers for a specific task queue.
     */
    WorkerFactory factory = WorkerFactory.newInstance(client);

    /*
     * Define the workflow worker. Workflow workers listen to a defined task queue and process
     * workflows and activities.
     */
    Worker worker = factory.newWorker(TASK_QUEUE);

    /*
     * Register the workflow implementation with the worker.
     * Workflow implementations must be known to the worker at runtime in
     * order to dispatch workflow tasks.
     */
    worker.registerWorkflowImplementationTypes(GreetingWorkflowImpl.class);

    /*
     * Register the workflow activity implementation with the worker. Since workflow activities are
     * stateless and thread-safe, we need to register a shared instance.
     */
    worker.registerActivitiesImplementations(new GreetingActivitiesImpl());

    /*
     * Start all the workers registered for a specific task queue.
     * The started workers then start polling for workflows and activities.
     */
    factory.start();

    /*
     * Define our workflow options. Note that the cron definition is not part of the
     * core workflow definition. Workflow options allow you to execute the same
     * workflow in different ways (for example with or without a cron, etc).
     *
     * Here we use setCronSchedule to define a cron for our workflow execution.
     * The cron format is parsed by the https://github.com/robfig/cron" library.
     * In addition to the standard "* * * * *" format Temporal also supports the "@every" as well as
     * other cron definition extensions. For example you could define "@every 2s" to define a cron definition
     * which executes our workflow every two seconds.
     *
     * The defined cron expression "* * * * *" means that our workflow should execute every minute.
     *
     * We also use setWorkflowExecutionTimeout to define the workflow execution total time (set to three minutes).
     * After this time, our workflow execution ends (and our cron will stop executing as well).
     *
     * The setWorkflowRunTimeout defines the amount of time after which a single workflow instance is terminated.
     *
     * So given all our settings in the WorkflowOptions we define the following:
     * "Execute our workflow once every minute for three minutes.
     * Once a workflow instance is started, terminate it after one minute (if its still running)"
     *
     */
    WorkflowOptions workflowOptions =
        WorkflowOptions.newBuilder()
            .setWorkflowId(WORKFLOW_ID)
            .setTaskQueue(TASK_QUEUE)
            .setCronSchedule("* * * * *")
            .setWorkflowExecutionTimeout(Duration.ofMinutes(3))
            .setWorkflowRunTimeout(Duration.ofMinutes(1))
            .build();

    // Create the workflow client stub. It is used to start our workflow execution.
    GreetingWorkflow workflow = client.newWorkflowStub(GreetingWorkflow.class, workflowOptions);

    try {
      // start workflow execution
      WorkflowExecution execution = WorkflowClient.start(workflow::greet, "World");
      System.out.println("Started " + execution);
    } catch (WorkflowExecutionAlreadyStarted e) {
      // Thrown when a workflow with the same WORKFLOW_ID is currently running
      System.out.println("Already running as " + e.getExecution());
    } catch (Throwable e) {
      e.printStackTrace();
      System.exit(1);
    }
  }
}