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HelloCron.java
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HelloCron.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.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);
}
}
}