Spring Boot

The Java/Kotlin SDK provides an integration module with Spring Boot: your Restate services become Spring beans, so you can use dependency injection, configuration properties, and the rest of the Spring ecosystem.

Get started from a template with the Java (Maven + Spring Boot) or Kotlin (Gradle + Spring Boot) Quickstart.

Dependencies

Use the Spring Boot starter instead of the plain HTTP SDK dependency. It pulls in the SDK and auto-configures the Restate endpoint and client.

Restate Java/Kotlin SDK 2.9.2 and later requires Netty 4.1.132 or later. Spring Boot dependency management can select an older Netty version and cause runtime errors.Upgrade to Spring Boot 3.5.13 or later, or set netty.version to 4.1.132.Final or later in your Maven properties or Gradle properties. Use Restate Java/Kotlin SDK 2.9.3 or later with Spring AI 2.x to avoid incompatible victools dependencies.

<properties>
    <restate.version>2.9.3</restate.version>
</properties>
<dependencies>
    <dependency>
        <groupId>dev.restate</groupId>
        <artifactId>sdk-spring-boot-starter</artifactId>
        <version>${restate.version}</version>
    </dependency>
</dependencies>

implementation("dev.restate:sdk-spring-boot-kotlin-starter:2.9.3")

Enabling Restate

Add @EnableRestate to your Spring Boot application:

package com.example.restatestarter;

import dev.restate.sdk.springboot.EnableRestate;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@EnableRestate
public class RestateStarterApplication {

	public static void main(String[] args) {
		SpringApplication.run(RestateStarterApplication.class, args);
	}

}

package com.example.restatestarter

import dev.restate.sdk.springboot.EnableRestate
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication

@SpringBootApplication
@EnableRestate
class RestateStarterApplication

fun main(args: Array<String>) {
	runApplication<RestateStarterApplication>(*args)
}

Defining services

Annotate your service class with @RestateComponent in addition to the usual @Service, @VirtualObject, or @Workflow annotation. Unlike the standalone setup, the service has no main: Spring Boot binds and serves it. @RestateComponent is like any other Spring’s @Component: inject configuration and other beans as usual (@Value, constructor injection, …).

@RestateComponent
@Service
public class Greeter {

  @Value("${greetingPrefix}")
  private String greetingPrefix;

  public record Greeting(String name) {}
  public record GreetingResponse(String message) {}

  @Handler
  public GreetingResponse greet(Greeting req) {
    // Durably execute a set of steps; resilient against failures
    String greetingId = Restate.random().nextUUID().toString();
    Restate.run("Notification", () -> sendNotification(greetingId, req.name));
    Restate.sleep(Duration.ofSeconds(1));
    Restate.run("Reminder", () -> sendReminder(greetingId, req.name));

    // Respond to caller
    return new GreetingResponse("You said " + greetingPrefix + " to " + req.name + "!");
  }
}

@RestateComponent
@Service
class Greeter {

  @Value("\${greetingPrefix}")
  lateinit var greetingPrefix: String

  @Serializable
  data class Greeting(val name: String)
  @Serializable
  data class GreetingResponse(val message: String)

  @Handler
  suspend fun greet(req: Greeting): GreetingResponse {
    // Durably execute a set of steps; resilient against failures
    val greetingId = random().nextUUID().toString()
    runBlock("Notification") { sendNotification(greetingId, req.name) }
    sleep(1.seconds)
    runBlock("Reminder") { sendReminder(greetingId, req.name) }

    // Respond to caller
    return GreetingResponse("You said $greetingPrefix to ${req.name}!")
  }
}

Everything inside the handler works exactly as in the standalone SDK: use the Restate static methods (Java) or the top-level functions in dev.restate.sdk.kotlin (Kotlin) for state, calls, side effects, and timers.

Calling Restate from Spring

The starter registers a Client bean. Inject it into any Spring component (controllers, scheduled tasks, …) to invoke your handlers from outside a Restate context:

package com.example.restatestarter;

import com.example.restatestarter.Greeter.Greeting;
import dev.restate.client.Client;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

	private final Client restateClient;

    public HelloController(Client restateClient) {
        this.restateClient = restateClient;
    }

    @GetMapping("/")
	public String index() {
		return restateClient.service(Greeter.class).greet(new Greeting("Alice")) + " from Spring Boot!";
	}

}

In Kotlin, inject the same Client bean through the constructor.

Configuration

Configure the SDK endpoint and the injected client via application.properties (or application.yml):

# Port where the Restate SDK endpoint is exposed (default 9080)
restate.sdk.http.port=9080

# Base URI of the Restate ingress, used by the injected Client
restate.client.base-uri=http://localhost:8080

Service- and handler-level options (retention, timeouts, retry policies, …) are set with restate.components.<ServiceName>.* properties. See service configuration for the full list.

SDKs

Services

Restate Cloud / BYOC / OSS

References

Dependencies

Enabling Restate

Defining services

Calling Restate from Spring

Configuration

​Dependencies

​Enabling Restate

​Defining services

​Calling Restate from Spring

​Configuration

Dependencies

Enabling Restate

Defining services

Calling Restate from Spring

Configuration