Add a new sample to start and interact with signal workflow directly via cadence client

src/main/java/com/uber/cadence/samples/clientsamples/SignalSample.java

@@ -0,0 +1,88 @@
+/*
+ *  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 com.uber.cadence.samples.clientsamples;
+
+import com.uber.cadence.WorkflowExecution;
+import com.uber.cadence.client.WorkflowClient;
+import com.uber.cadence.client.WorkflowOptions;
+import com.uber.cadence.samples.spring.common.Constant;
+import com.uber.cadence.samples.spring.models.SampleMessage;
+import com.uber.cadence.samples.spring.workflows.SignalWorkflow;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.time.Duration;
+import java.util.Scanner;
+
+// This class is a placeholder. Run the two binaries below to play with the
+// signal workflow sample.
+public class SignalSample {}
+
+// This binary starts a signal workflow and store the workflow ID into a local file
+// for future usage. It must be run first.
+class SignalWorkflowStarter {
+  public static void main(String[] args) throws IOException {
+    WorkflowClient workflowClient = CadenceUtil.getWorkflowClient();
+    WorkflowOptions workflowOptions =
+        new WorkflowOptions.Builder()
+            .setExecutionStartToCloseTimeout(Duration.ofSeconds(60))
+            .setTaskList(Constant.TASK_LIST)
+            .build();
+
+    // start a signal workflow using cadence client
+    SignalWorkflow signalWorkflow =
+        workflowClient.newWorkflowStub(SignalWorkflow.class, workflowOptions);
+    WorkflowExecution execution =
+        WorkflowClient.start(signalWorkflow::getGreeting, new SampleMessage("Uber"));
+    String workflowID = execution.getWorkflowId();
+    System.out.printf("WorkflowID: %s, RunID: %s", workflowID, execution.getRunId());
+
+    // store workflow ID for future use into a file. In prod, it may be persisted in a database
+    File workflowIDFile = new File("workflow_id.txt");
+    // always delete the file if it exists and create a new one.
+    workflowIDFile.delete();
+    workflowIDFile.createNewFile();
+    FileWriter writer = new FileWriter(workflowIDFile);
+    writer.write(workflowID);
+    writer.close();
+  }
+}
+
+// This binary retrieves the stored signal workflow ID from local file created by
+// SignalWorkflowStarter and send a signal to this workflow.
+class SignalSender {
+  public static void main(String[] args) throws FileNotFoundException {
+    // Get stored workflowID
+    File workflowIDFile = new File("workflow_id.txt");
+    Scanner scanner = new Scanner(workflowIDFile);
+    String workflowID = scanner.nextLine();
+    scanner.close();
+
+    // create a new stub using the retrieved workflowID
+    WorkflowClient workflowClient = CadenceUtil.getWorkflowClient();
+    // To send a signal, only workflowID is needed.
+    SignalWorkflow signalWorkflow =
+        workflowClient.newWorkflowStub(SignalWorkflow.class, workflowID);
+    // send signal to the workflow
+    signalWorkflow.waitForGreeting("Hello");
+
+    // cancel workflow directly via a signal
+    // signalWorkflow.cancel();
+  }
+}