- AWS Code Sample demonstrates how to poll for a decision task in a task list.

/* * Copyright 2010-2019, Inc. or its affiliates. All Rights Reserved.* * 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 * * * * 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 aws.example.helloswf; import com.amazonaws.regions.Regions; import; import; import*; import java.util.ArrayList; import java.util.List; import java.util.UUID; public class WorkflowWorker { private static final AmazonSimpleWorkflow swf = AmazonSimpleWorkflowClientBuilder.standard().withRegion(Regions.DEFAULT_REGION).build(); public static void main(String[] args) { PollForDecisionTaskRequest task_request = new PollForDecisionTaskRequest() .withDomain(HelloTypes.DOMAIN) .withTaskList(new TaskList().withName(HelloTypes.TASKLIST)); while (true) { System.out.println( "Polling for a decision task from the tasklist '" + HelloTypes.TASKLIST + "' in the domain '" + HelloTypes.DOMAIN + "'."); DecisionTask task = swf.pollForDecisionTask(task_request); String taskToken = task.getTaskToken(); if (taskToken != null) { try { executeDecisionTask(taskToken, task.getEvents()); } catch (Throwable th) { th.printStackTrace(); } } } } /** * The goal of this workflow is to execute at least one HelloActivity successfully. * * We pass the workflow execution's input to the activity, and we use the activity's result * as the output of the workflow. */ private static void executeDecisionTask(String taskToken, List<HistoryEvent> events) throws Throwable { List<Decision> decisions = new ArrayList<Decision>(); String workflow_input = null; int scheduled_activities = 0; int open_activities = 0; boolean activity_completed = false; String result = null; System.out.println("Executing the decision task for the history events: ["); for (HistoryEvent event : events) { System.out.println(" " + event); switch(event.getEventType()) { case "WorkflowExecutionStarted": workflow_input = event.getWorkflowExecutionStartedEventAttributes() .getInput(); break; case "ActivityTaskScheduled": scheduled_activities++; break; case "ScheduleActivityTaskFailed": scheduled_activities--; break; case "ActivityTaskStarted": scheduled_activities--; open_activities++; break; case "ActivityTaskCompleted": open_activities--; activity_completed = true; result = event.getActivityTaskCompletedEventAttributes() .getResult(); break; case "ActivityTaskFailed": open_activities--; break; case "ActivityTaskTimedOut": open_activities--; break; } } System.out.println("]"); if (activity_completed) { decisions.add( new Decision() .withDecisionType(DecisionType.CompleteWorkflowExecution) .withCompleteWorkflowExecutionDecisionAttributes( new CompleteWorkflowExecutionDecisionAttributes() .withResult(result))); } else { if (open_activities == 0 && scheduled_activities == 0) { ScheduleActivityTaskDecisionAttributes attrs = new ScheduleActivityTaskDecisionAttributes() .withActivityType(new ActivityType() .withName(HelloTypes.ACTIVITY) .withVersion(HelloTypes.ACTIVITY_VERSION)) .withActivityId(UUID.randomUUID().toString()) .withInput(workflow_input); decisions.add( new Decision() .withDecisionType(DecisionType.ScheduleActivityTask) .withScheduleActivityTaskDecisionAttributes(attrs)); } else { // an instance of HelloActivity is already scheduled or running. Do nothing, another // task will be scheduled once the activity completes, fails or times out } } System.out.println("Exiting the decision task with the decisions " + decisions); swf.respondDecisionTaskCompleted( new RespondDecisionTaskCompletedRequest() .withTaskToken(taskToken) .withDecisions(decisions)); } }

Sample Details

Service: swf

Author: soo-aws

Type: full-example