// *** Simple, fault-tolerant, sequential orchestration ***
String result = "";
result += ctx.callActivity("SayHello", "Tokyo", String.class).await() + ", ";
result += ctx.callActivity("SayHello", "London", String.class).await() + ", ";
result += ctx.callActivity("SayHello", "Seattle", String.class).await();
return result;

// Get the list of work-items to process
List<?> batch = ctx.callActivity("GetWorkBatch", List.class).await();

// Schedule each task to run in parallel
List<Task<Integer>> parallelTasks = batch.stream()
        .map(item -> ctx.callActivity("ProcessItem", item, Integer.class))
        .collect(Collectors.toList());

// Wait for all tasks to complete, then return the aggregated sum of the results
List<Integer> results = ctx.allOf(parallelTasks).await();
return results.stream().reduce(0, Integer::sum);

ApprovalInfo approvalInfo = ctx.getInput(ApprovalInfo.class);
ctx.callActivity("RequestApproval", approvalInfo).await();

Duration timeout = Duration.ofHours(72);
try {
    // Wait for an approval. A TaskCanceledException will be thrown if the timeout expires.
    boolean approved = ctx.waitForExternalEvent("ApprovalEvent", timeout, boolean.class).await();
    approvalInfo.setApproved(approved);

    ctx.callActivity("ProcessApproval", approvalInfo).await();
} catch (TaskCanceledException timeoutEx) {
    ctx.callActivity("Escalate", approvalInfo).await();
}

JobInfo jobInfo = ctx.getInput(JobInfo.class);
String jobId = jobInfo.getJobId();

String status = ctx.callActivity("GetJobStatus", jobId, String.class).await();
if (status.equals("Completed")) {
    // The job is done - we can exit now
    ctx.callActivity("SendAlert", jobId).await();
} else {
    // wait N minutes before doing the next poll
    Duration pollingDelay = jobInfo.getPollingDelay();
    ctx.createTimer(pollingDelay).await();

    // restart from the beginning
    ctx.continueAsNew(jobInfo);
}

return null;