Standalone Activities - Java SDK

SUPPORT, STABILITY, and DEPENDENCY INFO

Temporal Java SDK support for Standalone Activities is at Pre-release.

All APIs are experimental and may be subject to backwards-incompatible changes.

Standalone Activities are Activities that run independently, without being orchestrated by a Workflow. Instead of starting an Activity from within a Workflow Definition, you start a Standalone Activity directly from a Temporal Client using ActivityClient.

The way you write the Activity and register it with a Worker is identical to Workflow Activities. The only difference is that you execute a Standalone Activity directly from your Temporal Client.

This page covers the following:

• Get Started with Standalone Activities
• Define your Activity
• Run a Worker with the Activity registered
• Execute a Standalone Activity
• Start a Standalone Activity without waiting for the result
• Get a handle to an existing Standalone Activity
• Wait for the result of a Standalone Activity
• List Standalone Activities
• Count Standalone Activities
• Run Standalone Activities with Temporal Cloud

note

This documentation uses source code from the standaloneactivities sample.

Get Started with Standalone Activities

Prerequisites:

• Java 8+

• Temporal Java SDK (v1.35.0 or higher). See the Java Quickstart for install instructions.

• Temporal CLI (Pre-release version with Standalone Activity support)

  Download for your platform:

  macOS (Apple Silicon)

  curl -L https://github.com/temporalio/cli/releases/download/v1.6.2-standalone-activity/temporal_cli_1.6.2-standalone-activity_darwin_arm64.tar.gz | tar xz

  macOS (Intel)

  curl -L https://github.com/temporalio/cli/releases/download/v1.6.2-standalone-activity/temporal_cli_1.6.2-standalone-activity_darwin_amd64.tar.gz | tar xz

  Linux (arm64)

  curl -L https://github.com/temporalio/cli/releases/download/v1.6.2-standalone-activity/temporal_cli_1.6.2-standalone-activity_linux_arm64.tar.gz | tar xz

  Linux (amd64)

  curl -L https://github.com/temporalio/cli/releases/download/v1.6.2-standalone-activity/temporal_cli_1.6.2-standalone-activity_linux_amd64.tar.gz | tar xz

  Verify the installation:

  ./temporal --version
  # temporal version 1.6.2-standalone-activity (Server 1.31.0-151.2, UI 2.47.2)

  Move the binary to your PATH or run it from the current directory as ./temporal.

  danger

  If you see Standalone activity is disabled when running commands, you are using the standard Temporal CLI instead of the pre-release version above. The standard brew install temporal or brew upgrade temporal does not include Standalone Activity support during Pre-release.

Start the Temporal development server:

./temporal server start-dev

This command automatically starts the Temporal development server with the Web UI, and creates the default Namespace. It uses an in-memory database, so do not use it for real use cases.

Temporal Cloud

All code samples on this page use ClientConfigProfile.load() to configure the Temporal Client connection. It responds to environment variables and TOML configuration files, so the same code works against a local dev server and Temporal Cloud without changes. See Run Standalone Activities with Temporal Cloud below.

The Temporal Server will now be available for client connections on localhost:7233, and the Temporal Web UI will now be accessible at http://localhost:8233. Standalone Activities are available from the nav bar item located towards the top left of the page:

Clone the samples-java repository to follow along:

git clone https://github.com/temporalio/samples-java.git
cd samples-java

The sample consists of separate programs in the standaloneactivities package:

core/src/main/java/io/temporal/samples/standaloneactivities/
├── GreetingActivities.java       # Activity interface
├── GreetingActivitiesImpl.java   # Activity implementation
├── StandaloneActivityWorker.java # Worker that processes activity tasks
├── ExecuteActivity.java          # Starts an activity and waits for the result
├── StartActivity.java            # Starts an activity without blocking
├── ListActivities.java           # Lists activity executions
└── CountActivities.java          # Counts activity executions

Define your Activity

An Activity in the Temporal Java SDK is an interface annotated with @ActivityInterface, with methods annotated with @ActivityMethod. The way you define a Standalone Activity is identical to how you define an Activity orchestrated by a Workflow. In fact, the same Activity can be executed both as a Standalone Activity and as a Workflow Activity.

GreetingActivities.java

@ActivityInterface
public interface GreetingActivities {

  @ActivityMethod
  String composeGreeting(String greeting, String name);
}

GreetingActivitiesImpl.java

public class GreetingActivitiesImpl implements GreetingActivities {

  private static final Logger log = LoggerFactory.getLogger(GreetingActivitiesImpl.class);

  @Override
  public String composeGreeting(String greeting, String name) {
    log.info("Composing greeting...");
    return greeting + ", " + name + "!";
  }
}

Run a Worker with the Activity registered

Running a Worker for Standalone Activities is the same as running a Worker for Workflow Activities — you create a WorkerFactory, register the Activity implementation, and call factory.start(). The Worker doesn't need to know whether the Activity will be invoked from a Workflow or as a Standalone Activity. See How to run a Worker for more details on Worker setup and configuration options.

StandaloneActivityWorker.java

ClientConfigProfile profile = ClientConfigProfile.load();
WorkflowServiceStubs service =
    WorkflowServiceStubs.newServiceStubs(profile.toWorkflowServiceStubsOptions());

WorkflowClient client = WorkflowClient.newInstance(service, profile.toWorkflowClientOptions());
WorkerFactory factory = WorkerFactory.newInstance(client);
Worker worker = factory.newWorker(TASK_QUEUE);
worker.registerActivitiesImplementations(new GreetingActivitiesImpl());
factory.start();
System.out.println("Worker running on task queue: " + TASK_QUEUE);

Open a new terminal, navigate to the samples-java directory, and run the Worker:

./gradlew -q execute -PmainClass=io.temporal.samples.standaloneactivities.StandaloneActivityWorker

Leave this terminal running — the Worker needs to stay up to process activities.

Execute a Standalone Activity

Use ActivityClient.execute() to execute a Standalone Activity and block until it completes. Call this from your application code, not from inside a Workflow Definition. This durably enqueues your Standalone Activity in the Temporal Server, waits for it to be executed on your Worker, and then returns the typed result.

ExecuteActivity.java

ActivityClient client =
    ActivityClient.newInstance(
        service,
        ActivityClientOptions.newBuilder().setNamespace(profile.getNamespace()).build());

StartActivityOptions options =
    StartActivityOptions.newBuilder()
        .setId(ACTIVITY_ID)
        .setTaskQueue(TASK_QUEUE)
        .setStartToCloseTimeout(Duration.ofSeconds(10))
        .build();

String result =
    client.execute(
        GreetingActivities.class,
        GreetingActivities::composeGreeting,
        options,
        "Hello",
        "World");
System.out.println("Activity result: " + result);

The typed execute() API takes the Activity interface class and an unbound method reference. The SDK uses the method reference to infer the Activity type name and result type at runtime. You can also call Activities by string type name:

// Using a string type name
String result = client.execute("ComposeGreeting", String.class, options, "Hello", "World");

StartActivityOptions requires id, taskQueue, and at least one of startToCloseTimeout or scheduleToCloseTimeout.

To run it:

1. Make sure the Temporal Server is running (from the Get Started step above).
2. Make sure the Worker is running (from the Run a Worker step above).
3. Open a new terminal, navigate to the samples-java directory, and run:

./gradlew -q execute -PmainClass=io.temporal.samples.standaloneactivities.ExecuteActivity

Or use the Temporal CLI:

./temporal activity execute \
  --type ComposeGreeting \
  --activity-id standalone-activity-id \
  --task-queue standalone-activity-task-queue \
  --start-to-close-timeout 10s \
  --input '"Hello"' \
  --input '"World"'

Start a Standalone Activity without waiting for the result

Starting a Standalone Activity means sending a request to the Temporal Server to durably enqueue your Activity job, without waiting for it to be executed by your Worker.

Use ActivityClient.start() to start a Standalone Activity and get a handle without waiting for the result:

StartActivity.java

ActivityHandle<String> handle =
    client.start(
        GreetingActivities.class,
        GreetingActivities::composeGreeting,
        options,
        "Hello",
        "World");
System.out.println("Started activity ID: " + ACTIVITY_ID);

// Wait for the result later
String result = handle.getResult();
System.out.println("Activity result: " + result);

With the Temporal Server and Worker running, open a new terminal in the samples-java directory and run:

./gradlew -q execute -PmainClass=io.temporal.samples.standaloneactivities.StartActivity

Or use the Temporal CLI:

./temporal activity start \
  --type ComposeGreeting \
  --activity-id standalone-activity-id \
  --task-queue standalone-activity-task-queue \
  --start-to-close-timeout 10s \
  --input '"Hello"' \
  --input '"World"'

Get a handle to an existing Standalone Activity

Use client.getHandle() to create a typed handle to a previously started Standalone Activity:

ActivityHandle<String> handle =
    client.getHandle("standalone-activity-id", null, String.class);

Pass null as the run ID to target the latest run of the given activity ID. You can then use the handle to wait for the result, describe, cancel, or terminate the Activity.

Wait for the result of a Standalone Activity

Under the hood, calling client.execute() is the same as calling client.start() to durably enqueue the Standalone Activity, and then calling handle.getResult() to block until the Activity completes and return the result:

String result = handle.getResult();

To wait asynchronously without blocking the calling thread, use handle.getResultAsync(), which returns a CompletableFuture<R>:

CompletableFuture<String> future = handle.getResultAsync();

Or use the Temporal CLI to wait for a result by Activity ID:

./temporal activity result --activity-id standalone-activity-id

List Standalone Activities

Use client.listExecutions() to list Standalone Activity Executions that match a List Filter query. The result is a Stream<ActivityExecutionMetadata> that fetches pages from the server on demand as the stream is consumed.

These APIs return only Standalone Activity Executions. Activities running inside Workflows are not included.

ListActivities.java

client
    .listExecutions("TaskQueue = '" + TASK_QUEUE + "'")
    .forEach(
        info ->
            System.out.printf(
                "ActivityID: %s, Type: %s, Status: %s%n",
                info.getActivityId(), info.getActivityType(), info.getStatus()));

Run it:

./gradlew -q execute -PmainClass=io.temporal.samples.standaloneactivities.ListActivities

Or use the Temporal CLI:

./temporal activity list

The query parameter accepts the same List Filter syntax used for Workflow Visibility. For example, "ActivityType = 'composeGreeting' AND Status = 'Running'".

Count Standalone Activities

Use client.countExecutions() to count Standalone Activity Executions that match a List Filter query. This returns the total count of executions (running, completed, failed, etc.) — not the number of queued tasks. It works the same way as counting Workflow Executions.

CountActivities.java

ActivityExecutionCount resp = client.countExecutions("TaskQueue = '" + TASK_QUEUE + "'");
System.out.println("Total activities: " + resp.getCount());
resp.getGroups()
    .forEach(
        group ->
            System.out.println("Group " + group.getGroupValues() + ": " + group.getCount()));

Run it:

./gradlew -q execute -PmainClass=io.temporal.samples.standaloneactivities.CountActivities

Or use the Temporal CLI:

./temporal activity count

Run Standalone Activities with Temporal Cloud

The code samples on this page use ClientConfigProfile.load(), so the same code works against Temporal Cloud — just configure the connection via environment variables or a TOML profile. No code changes are needed.

For a step-by-step guide on connecting to Temporal Cloud, including Namespace creation, certificate generation, and authentication setup in the Cloud UI, see Connect to Temporal Cloud.

Connect with mTLS

Set these environment variables with values from your Temporal Cloud Namespace settings:

export TEMPORAL_ADDRESS=<your-namespace>.<your-account-id>.tmprl.cloud:7233
export TEMPORAL_NAMESPACE=<your-namespace>.<your-account-id>
export TEMPORAL_TLS_CLIENT_CERT_PATH='path/to/your/client.pem'
export TEMPORAL_TLS_CLIENT_KEY_PATH='path/to/your/client.key'

Connect with an API key

Set these environment variables with values from your Temporal Cloud API key settings:

export TEMPORAL_ADDRESS=<region>.<cloud_provider>.api.temporal.io:7233
export TEMPORAL_NAMESPACE=<your-namespace>.<your-account-id>
export TEMPORAL_API_KEY=<your-api-key>

Then run the Worker and starter code as shown in the earlier sections.