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Maxim Fateev
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Added HelloWorld and HelloSignal
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‎README.md‎

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@@ -21,7 +21,7 @@ After cadence-client library is available just run
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to build the samples. Verify that they actually can run:
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mvn exec:java -Dexec.mainClass=com.uber.cadence.samples.helloworld.HelloWorld
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mvn exec:java -Dexec.mainClass=com.uber.cadence.samples.helloworld.HelloActivity
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## Overview of the Samples
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To run hello world:
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mvn exec:java -Dexec.mainClass=com.uber.cadence.samples.helloworld.HelloWorld
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mvn exec:java -Dexec.mainClass=com.uber.cadence.samples.helloworld.HelloActivity
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### File Processing
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src/main/java/com/uber/cadence/samples/helloworld/HelloWorld.java renamed to src/main/java/com/uber/cadence/samples/helloworld/HelloActivity.java

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* Hello World Cadence workflow that executes a single activity.
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* Requires a local instance of Cadence server running.
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*/
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public class HelloWorld {
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public class HelloActivity {
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private static final String TASK_LIST = "HelloWorld";
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private static final String TASK_LIST = "HelloActivity";
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/**
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* Workflow interface has to have at least one method annotated with @WorkflowMethod.
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/**
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* Activity stub implements activity interface and proxies calls to it to Cadence activity invocations.
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* As activities are reentrant only a single stub can be used for multiple activity invocations.
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*/
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private final HelloWorld.GreetingActivities activities = Workflow.newActivityStub(
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private final GreetingActivities activities = Workflow.newActivityStub(
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GreetingActivities.class,
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new ActivityOptions.Builder().setScheduleToCloseTimeoutSeconds(10).build());
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@Override
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public String getGreeting(String name) {
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// This is blocking call that returns only after
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// This is blocking call that returns only after activity is completed.
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return activities.composeGreeting("Hello", name );
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}
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}

‎src/main/java/com/uber/cadence/samples/helloworld/HelloChild.java‎

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/*
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* Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Modifications copyright (C) 2017 Uber Technologies, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License"). You may not
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* use this file except in compliance with the License. A copy of the License is
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* located at
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*
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* http://aws.amazon.com/apache2.0
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*
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* or in the "license" file accompanying this file. This file is distributed on
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* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package com.uber.cadence.samples.helloworld;
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import com.uber.cadence.client.CadenceClient;
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import com.uber.cadence.client.WorkflowOptions;
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import com.uber.cadence.worker.Worker;
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import com.uber.cadence.workflow.Workflow;
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import com.uber.cadence.workflow.WorkflowMethod;
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import org.apache.log4j.BasicConfigurator;
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import org.apache.log4j.Level;
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import org.apache.log4j.Logger;
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import static com.uber.cadence.samples.common.SampleConstants.DOMAIN;
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/**
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* Hello World Cadence workflow that executes a single child workflow.
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* Requires a local instance of Cadence server running.
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*/
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public class HelloChild {
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private static final String TASK_LIST = "HelloChild";
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/**
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* Workflow interface has to have at least one method annotated with @WorkflowMethod.
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*/
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public interface GreetingWorkflow {
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/**
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* @return greeting string
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*/
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@WorkflowMethod
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String getGreeting(String name);
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}
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/**
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* Activity interface is just a POJI
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*/
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public interface GreetingChild {
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@WorkflowMethod
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String composeGreeting(String greeting, String name);
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}
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/**
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* GreetingWorkflow implementation that calls GreetingsActivities#printIt.
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*/
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public static class GreetingWorkflowImpl implements GreetingWorkflow {
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@Override
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public String getGreeting(String name) {
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// Workflows are stateful. So new stub must be created for each new child.
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GreetingChild child = Workflow.newChildWorkflowStub(GreetingChild.class);
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// This is blocking call that returns only after child is completed.
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return child.composeGreeting("Hello", name );
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}
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}
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/**
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* Child workflow implementation.
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* Workflow implementation must always be public for the Cadence to be able to create instances.
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*/
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public static class GreetingChildImpl implements GreetingChild {
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@Override
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public String composeGreeting(String greeting, String name) {
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return greeting + " " + name + "!";
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}
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}
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public static void main(String[] args) {
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BasicConfigurator.configure();
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Logger.getRootLogger().setLevel(Level.WARN);
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// Start a worker that hosts both parent and child workflow implementations.
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Worker worker = new Worker(DOMAIN, TASK_LIST);
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worker.registerWorkflowImplementationTypes(GreetingWorkflowImpl.class, GreetingChildImpl.class);
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// Start listening to the workflow task list.
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worker.start();
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// Start a workflow execution. Usually it is done from another program.
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CadenceClient cadenceClient = CadenceClient.newInstance(DOMAIN);
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// Get a workflow stub using the same task list the worker uses.
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WorkflowOptions workflowOptions = new WorkflowOptions.Builder()
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.setTaskList(TASK_LIST)
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.setExecutionStartToCloseTimeoutSeconds(30)
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.build();
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GreetingWorkflow workflow = cadenceClient.newWorkflowStub(GreetingWorkflow.class,
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workflowOptions);
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// Execute a workflow waiting for it complete.
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String greeting = workflow.getGreeting("World");
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System.out.println(greeting);
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System.exit(0);
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}
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}

‎src/main/java/com/uber/cadence/samples/helloworld/HelloSignal.java‎

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/*
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* Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Modifications copyright (C) 2017 Uber Technologies, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License"). You may not
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* use this file except in compliance with the License. A copy of the License is
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* located at
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*
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* http://aws.amazon.com/apache2.0
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*
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* or in the "license" file accompanying this file. This file is distributed on
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* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package com.uber.cadence.samples.helloworld;
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import com.uber.cadence.WorkflowExecution;
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import com.uber.cadence.WorkflowIdReusePolicy;
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import com.uber.cadence.client.CadenceClient;
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import com.uber.cadence.client.WorkflowOptions;
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import com.uber.cadence.worker.Worker;
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import com.uber.cadence.workflow.ActivityOptions;
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import com.uber.cadence.workflow.CompletablePromise;
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import com.uber.cadence.workflow.Promise;
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import com.uber.cadence.workflow.SignalMethod;
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import com.uber.cadence.workflow.Workflow;
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import com.uber.cadence.workflow.WorkflowException;
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import com.uber.cadence.workflow.WorkflowMethod;
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import static com.uber.cadence.samples.common.SampleConstants.DOMAIN;
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/**
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* Hello World Cadence workflow that blocks until a signal is received.
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* Requires a local instance of Cadence server running.
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*/
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public class HelloSignal {
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private static final String TASK_LIST = "HelloSignal";
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/**
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* Workflow interface has to have at least one method annotated with @WorkflowMethod.
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*/
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public interface GreetingWorkflow {
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/**
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* @return greeting string
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*/
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@WorkflowMethod
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String getGreeting();
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/**
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* Receives name through an external signal.
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*/
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@SignalMethod
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void waitForName(String name);
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}
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/**
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* GreetingWorkflow implementation that calls GreetingsActivities#printIt.
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*/
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public static class GreetingWorkflowImpl implements GreetingWorkflow {
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private final CompletablePromise<String> name = Workflow.newCompletablePromise();
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@Override
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public String getGreeting() {
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return "Hello " + name.get() + "!";
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}
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@Override
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public void waitForName(String name) {
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this.name.complete(name);
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}
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}
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public static void main(String[] args) {
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// Start a worker that hosts the workflow implementation
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Worker worker = new Worker(DOMAIN, TASK_LIST);
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worker.registerWorkflowImplementationTypes(GreetingWorkflowImpl.class);
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worker.start();
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// Start a workflow execution. Usually it is done from another program.
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CadenceClient cadenceClient = CadenceClient.newInstance(DOMAIN);
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// Get a workflow stub using the same task list the worker uses.
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WorkflowOptions workflowOptions = new WorkflowOptions.Builder()
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.setTaskList(TASK_LIST)
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.setExecutionStartToCloseTimeoutSeconds(30)
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.build();
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GreetingWorkflow workflow = cadenceClient.newWorkflowStub(GreetingWorkflow.class,
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workflowOptions);
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// Start workflow asynchronously to not use another thread to signal.
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WorkflowExecution execution = CadenceClient.asyncStart(workflow::getGreeting);
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// After asyncStart for getGreeting returns the workflow is guaranteed to be started.
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// So we can send signal to it using workflow stub.
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workflow.waitForName("World");
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// Calling synchronous getGreeting after workflow has started reconnects to the existing workflow and
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// blocks until result is available. Note this behavior assumes that WorkflowOptions are not configured
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// with WorkflowIdReusePolicy.AllowDuplicate. In that case the call would fail with IllegalStateException.
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String greeting = workflow.getGreeting();
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System.out.println(greeting);
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System.exit(0);
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}
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}

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