Files
Donald Pinckney 0c8586b4c2 Add Java SDK support (#42)
* Add Java SDK reference files (11 files)

Create complete Java reference documentation covering:
- java.md: Entry point with quick start tutorial, key concepts
- patterns.md: 17 patterns (signals, queries, updates, child workflows,
  saga, cancellation scopes, heartbeating, etc.)
- determinism.md: Safe alternatives table, forbidden operations
- determinism-protection.md: Convention-based enforcement (no sandbox)
- error-handling.md: ApplicationFailure, retry/timeout config
- gotchas.md: Non-deterministic operations, cancellation, heartbeating
- testing.md: TestWorkflowEnvironment, Mockito mocking, replay testing
- versioning.md: Workflow.getVersion(), worker versioning
- data-handling.md: Jackson, PayloadConverter, encryption, search attributes
- observability.md: SLF4J logging, Micrometer metrics
- advanced-features.md: Schedules, async completion, worker tuning

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Fix Java alignment issues from self-review

- Reduce gotchas.md Non-Deterministic Operations from ~94 lines to ~12
  (reference determinism.md instead of duplicating)
- Remove Workflow Failure Exception Types duplication from error-handling.md
  (keep only in advanced-features.md)
- Expand versioning.md Worker Versioning with Key Concepts, PINNED vs
  AUTO_UPGRADE, Deployment Strategies subsections
- Fix section names to match Python reference style:
  Activity Heartbeat Details, Handling Activity Errors,
  Retry Policy Configuration, Workflow Test Environment,
  Mocking Activities, Workflow Replay Testing
- Reduce data-handling.md Payload Encryption verbosity
- Reduce observability.md Logger Customization verbosity
- Reduce testing.md to single approach per section
- Rename determinism.md "Convention-Based Enforcement" to "SDK Protection"
- Fix handler guidance in patterns.md to match Python

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Fix correctness issues in Java reference files

- patterns.md: Fix Queries section — ActivityStub → typed interface
  (Workflow.newActivityStub returns the typed interface, not ActivityStub)
- data-handling.md: Add missing ProtobufPayloadConverter to default
  converter chain (4th of 5 converters)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Add Java to SKILL.md and core/determinism.md

- SKILL.md: Add "Temporal Java" trigger phrase, update Overview to
  list Java, add Java entry to Getting Started references
- core/determinism.md: Add Java entry to SDK Protection Mechanisms
  (no sandbox, convention-based, NonDeterministicException at replay)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Apply manual editorial fixes to Java references

- java.md: Remove "Understanding Replay" section (covered by Overview),
  simplify File Organization note (no sandbox rationale)
- gotchas.md: Move Heartbeating before Cancellation, make Wrong Retry
  Classification brief with reference (not inline examples)
- error-handling.md: Remove editorializing from Workflow Failure note
- determinism-protection.md: Remove cross-language comparison paragraph
  (state Java's approach on its own terms)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Add temporal-workflowcheck static analysis to Java determinism docs

- determinism-protection.md: Add "Static Analysis with temporal-workflowcheck"
  section with Gradle/Maven setup, manual run, and suppression instructions.
  Beta warning included.
- determinism.md: Update overview and SDK Protection to reference workflowcheck
- core/determinism.md: Update Java entry in SDK Protection Mechanisms

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Integrate feedback from Go PR into Java patterns

- Updates: Add validator note — validators must not mutate state or
  block (matches note added to Python, TypeScript, Go, and core)
- Saga Pattern: Use Workflow.newDetachedCancellationScope() for
  compensations so they execute even if the workflow is cancelled
  (mirrors Go's workflow.NewDisconnectedContext pattern)

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

* docs: add @WorkflowInit description to java.md Key Concepts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* mark java as supported

* Apply suggestions from code review

Co-authored-by: Brian Strauch <brian@brianstrauch.com>

* strongly recommend java 21+

* Softened stance on static checker and replay testing.

* address python/typescript sandboxing comment

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Brian Strauch <brian.strauch@temporal.io>
Co-authored-by: Brian Strauch <brian@brianstrauch.com>
2026-04-02 17:07:33 -04:00

5.7 KiB

Java SDK Advanced Features

Schedules

Create recurring workflow executions.

import io.temporal.client.schedules.*;

ScheduleClient scheduleClient = ScheduleClient.newInstance(service);

// Create a schedule
String scheduleId = "daily-report";
ScheduleHandle handle = scheduleClient.createSchedule(
    scheduleId,
    Schedule.newBuilder()
        .setAction(
            ScheduleActionStartWorkflow.newBuilder()
                .setWorkflowType(DailyReportWorkflow.class)
                .setOptions(
                    WorkflowOptions.newBuilder()
                        .setWorkflowId("daily-report")
                        .setTaskQueue("reports")
                        .build()
                )
                .build()
        )
        .setSpec(
            ScheduleSpec.newBuilder()
                .setIntervals(
                    List.of(new ScheduleIntervalSpec(Duration.ofDays(1)))
                )
                .build()
        )
        .build(),
    ScheduleOptions.newBuilder().build()
);

// Manage schedules
ScheduleHandle scheduleHandle = scheduleClient.getHandle(scheduleId);
scheduleHandle.pause("Maintenance window");
scheduleHandle.unpause();
scheduleHandle.trigger();  // Run immediately
scheduleHandle.delete();

Async Activity Completion

For activities that complete asynchronously (e.g., human tasks, external callbacks). If you configure a heartbeat timeout on this activity, the external completer is responsible for sending heartbeats via the async handle.

Note: If the external system can reliably Signal back with the result and doesn't need to Heartbeat or receive Cancellation, consider using signals instead.

public class ApprovalActivitiesImpl implements ApprovalActivities {
    @Override
    public String requestApproval(String requestId) {
        ActivityExecutionContext ctx = Activity.getExecutionContext();

        // Get task token for async completion
        byte[] taskToken = ctx.getTaskToken();

        // Store task token for later completion (e.g., in database)
        storeTaskToken(requestId, taskToken);

        // Mark this activity as waiting for external completion
        ctx.doNotCompleteOnReturn();

        return null; // Return value is ignored
    }
}

// Later, complete the activity from another process
public void completeApproval(String requestId, boolean approved) {
    WorkflowServiceStubs service = WorkflowServiceStubs.newLocalServiceStubs();
    WorkflowClient client = WorkflowClient.newInstance(service);

    ActivityCompletionClient completionClient = client.newActivityCompletionClient();

    byte[] taskToken = getTaskToken(requestId);

    if (approved) {
        completionClient.complete(taskToken, "approved");
    } else {
        completionClient.completeExceptionally(
            taskToken,
            new RuntimeException("Rejected")
        );
    }
}

Worker Tuning

Configure worker performance settings.

WorkerOptions workerOptions = WorkerOptions.newBuilder()
    // Max concurrent workflow task executions (default: 200)
    .setMaxConcurrentWorkflowTaskExecutionSize(200)
    // Max concurrent activity executions (default: 200)
    .setMaxConcurrentActivityExecutionSize(200)
    // Max concurrent local activity executions (default: 200)
    .setMaxConcurrentLocalActivityExecutionSize(200)
    // Max workflow task pollers (default: 5)
    .setMaxConcurrentWorkflowTaskPollers(5)
    // Max activity task pollers (default: 5)
    .setMaxConcurrentActivityTaskPollers(5)
    .build();

WorkerFactory factory = WorkerFactory.newInstance(client);
Worker worker = factory.newWorker("my-queue", workerOptions);
worker.registerWorkflowImplementationTypes(MyWorkflowImpl.class);
worker.registerActivitiesImplementations(new MyActivitiesImpl());
factory.start();

Workflow Failure Exception Types

Control which exceptions cause workflow failures vs workflow task failures.

By default, only ApplicationFailure (and its subclasses) fail the workflow execution. All other exceptions fail the workflow task, causing the task to retry indefinitely until the code is fixed or the workflow is terminated.

Per-Workflow Configuration

Use WorkflowImplementationOptions to specify which exception types should fail the workflow:

Worker worker = factory.newWorker("my-queue");
worker.registerWorkflowImplementationTypes(
    WorkflowImplementationOptions.newBuilder()
        .setFailWorkflowExceptionTypes(
            IllegalArgumentException.class,
            CustomBusinessException.class
        )
        .build(),
    MyWorkflowImpl.class
);

With this configuration, IllegalArgumentException and CustomBusinessException thrown from the workflow will fail the workflow execution instead of just the workflow task.

Worker-Level Configuration

Apply to all workflows registered on the worker:

WorkerFactoryOptions factoryOptions = WorkerFactoryOptions.newBuilder()
    .setWorkflowHostLocalTaskQueueScheduleToStartTimeout(Duration.ofSeconds(10))
    .build();
WorkerFactory factory = WorkerFactory.newInstance(client, factoryOptions);

Worker worker = factory.newWorker("my-queue");
// Register each workflow type with its own failure exception types
worker.registerWorkflowImplementationTypes(
    WorkflowImplementationOptions.newBuilder()
        .setFailWorkflowExceptionTypes(
            IllegalArgumentException.class,
            CustomBusinessException.class
        )
        .build(),
    MyWorkflowImpl.class,
    AnotherWorkflowImpl.class
);
  • Tip for testing: Set setFailWorkflowExceptionTypes(Throwable.class) so any unhandled exception fails the workflow immediately rather than retrying the workflow task forever. This surfaces bugs faster.