Serving

Restate services can run in two ways: as an HTTP endpoint or as AWS Lambda functions.

Creating an HTTP endpoint

Use either or as SDK dependency.
Create an endpoint
Bind one or multiple services to it
Listen on the specified port (default 9080) for connections and requests.

import dev.restate.sdk.endpoint.Endpoint;
import dev.restate.sdk.http.vertx.RestateHttpServer;

class MyApp {
  public static void main(String[] args) {
    RestateHttpServer.listen(
        Endpoint.bind(new MyService()).bind(new MyObject()).bind(new MyWorkflow()), 8080);
  }
}

fun main() {
  RestateHttpServer.listen(
      endpoint {
        bind(MyService())
        bind(MyObject())
        bind(MyWorkflow())
      }
  )
}

On JDK 23+, the SDK uses a native library and prints a native-access warning at startup. To silence it, enable native access by passing --enable-native-access=ALL-UNNAMED as a JVM argument, or by setting Enable-Native-Access: ALL-UNNAMED in your JAR manifest.

Creating a Lambda handler

Use either or as SDK dependency.
Extend the class BaseRestateLambdaHandler
Override the register method
Bind one or multiple services to the builder

import dev.restate.sdk.endpoint.Endpoint;
import dev.restate.sdk.lambda.BaseRestateLambdaHandler;

class MyLambdaHandler extends BaseRestateLambdaHandler {
  @Override
  public void register(Endpoint.Builder builder) {
    builder.bind(new MyService()).bind(new MyObject());
  }
}

import dev.restate.sdk.endpoint.Endpoint
import dev.restate.sdk.lambda.BaseRestateLambdaHandler

class MyLambdaHandler : BaseRestateLambdaHandler() {
  override fun register(builder: Endpoint.Builder) {
    builder.bind(MyService()).bind(MyObject())
  }
}

The implementation of your services and handlers remains the same for both deployment options. Have a look at the deployment section for guidance on how to deploy your services on AWS Lambda.

Handler execution

For Java services, the SDK uses virtual threads by default on JDK 21 and newer. On older JDK versions, it falls back to Executors.newCachedThreadPool(). Kotlin services use Dispatchers.Default by default.

Customizing the handler executor

Override the Java executor or Kotlin coroutine context when your service needs a different execution model:

builder.bind(
    new Greeter(),
    HandlerRunner.Options.withExecutor(Executors.newVirtualThreadPerTaskExecutor()));

builder.bind(
    Greeter(),
    HandlerRunner.Options(
        coroutineContext = Executors.newVirtualThreadPerTaskExecutor().asCoroutineDispatcher(),
    ),
)

Validating request identity

SDKs can validate that incoming requests come from a particular Restate instance. You can find out more about request identity in the Security docs. You will need to use the request identity dependency .

import dev.restate.sdk.auth.signing.RestateRequestIdentityVerifier;
import dev.restate.sdk.endpoint.Endpoint;
import dev.restate.sdk.http.vertx.RestateHttpServer;

class MySecureApp {
  public static void main(String[] args) {
    var endpoint =
        Endpoint.bind(new MyService())
            .withRequestIdentityVerifier(
                RestateRequestIdentityVerifier.fromKeys(
                    "publickeyv1_w7YHemBctH5Ck2nQRQ47iBBqhNHy4FV7t2Usbye2A6f"));
    RestateHttpServer.listen(endpoint);
  }
}

import dev.restate.sdk.auth.signing.RestateRequestIdentityVerifier
import dev.restate.sdk.http.vertx.RestateHttpServer
import dev.restate.sdk.kotlin.endpoint.endpoint

fun main() {
  RestateHttpServer.listen(
      endpoint {
        bind(MyService())
        requestIdentityVerifier =
            RestateRequestIdentityVerifier.fromKeys(
                "publickeyv1_w7YHemBctH5Ck2nQRQ47iBBqhNHy4FV7t2Usbye2A6f",
            )
      }
  )
}

SDKs

Services

Restate Cloud

Restate BYOC

Self-hosted Restate

References

Creating an HTTP endpoint

Creating a Lambda handler

Handler execution

Validating request identity

​Creating an HTTP endpoint

​Creating a Lambda handler

​Handler execution

​Validating request identity

Creating an HTTP endpoint

Creating a Lambda handler

Handler execution

Validating request identity