Merge pull request #41 from RaymondKroon/sideeffect-example

Simple side effect workflow

Author: meiliang86

src/main/java/com/uber/cadence/samples/hello/HelloSideEffect.java

@@ -0,0 +1,69 @@
+package com.uber.cadence.samples.hello;
+
+import static com.uber.cadence.samples.common.SampleConstants.DOMAIN;
+
+import com.uber.cadence.client.WorkflowClient;
+import com.uber.cadence.worker.Worker;
+import com.uber.cadence.workflow.QueryMethod;
+import com.uber.cadence.workflow.Workflow;
+import com.uber.cadence.workflow.WorkflowMethod;
+import java.util.UUID;
+
+/**
+ * Hello SideEffect Cadence workflow that sets a SideEffect. The set value can be queried Requires a
+ * local instance the Cadence service to be running.
+ */
+public class HelloSideEffect {
+
+  static final String TASK_LIST = "HelloSideEffect";
+
+  /** Workflow interface has to have at least one method annotated with @WorkflowMethod. */
+  public interface SideEffectWorkflow {
+    @WorkflowMethod(executionStartToCloseTimeoutSeconds = 10, taskList = TASK_LIST)
+    void start();
+
+    /** @return set value */
+    @QueryMethod
+    String get();
+  }
+
+  public static class SideEffectWorkflowImpl implements SideEffectWorkflow {
+
+    private String value = "";
+
+    @Override
+    public void start() {
+      this.value =
+          Workflow.sideEffect(
+              String.class,
+              () -> {
+                return UUID.randomUUID().toString();
+              });
+    }
+
+    @Override
+    public String get() {
+      return this.value;
+    }
+  }
+
+  public static void main(String[] args) {
+    // Start a worker that hosts both workflow and activity implementations.
+    Worker.Factory factory = new Worker.Factory(DOMAIN);
+    Worker worker = factory.newWorker(TASK_LIST);
+    // Workflows are stateful. So you need a type to create instances.
+    worker.registerWorkflowImplementationTypes(SideEffectWorkflowImpl.class);
+    // Start listening to the workflow and activity task lists.
+    factory.start();
+
+    // Start a workflow execution. Usually this is done from another program.
+    WorkflowClient workflowClient = WorkflowClient.newInstance(DOMAIN);
+    // Get a workflow stub using the same task list the worker uses.
+    SideEffectWorkflow workflow = workflowClient.newWorkflowStub(SideEffectWorkflow.class);
+    // Execute a workflow waiting for it to complete.
+    workflow.start();
+    // Query and print the set value
+    System.out.println(workflow.get());
+    System.exit(0);
+  }
+}