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a microservices library - scalecube-services is a high throughput, low latency reactive microservices library built to scale. it features: API-Gateways, service-discovery, service-load-balancing, the architecture supports plug-and-play service communication modules and features. built to provide performance and low-latency real-time stream-processing. its open and designed to accommodate changes. (no sidecar in a form of broker or any kind)

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An open-source project that is focused on streamlining reactive-programming of Microservices Reactive-systems that scale, built by developers for developers.

ScaleCube Services provides a low latency Reactive Microservices library for peer-to-peer service registry and discovery based on gossip protocol, without single point-of-failure or bottlenecks.

Scalecube more gracefully address the cross cutting concernes of distributed microservices architecture.

ScaleCube Services Features:

  • Provision and interconnect microservices peers in a cluster
  • Fully Distributed with No single-point-of-failure or single-point-of-bottleneck
  • Fast - Low latency and high throughput
  • Scaleable over- cores, jvms, clusters, regions.
  • Built-in Service Discovery and service routing
  • Zero configuration, automatic peer-to-peer service discovery using SWIM cluster membership protocol
  • Simple non-blocking, asynchronous programming model
  • Reactive Streams support.
    • Fire And Forget - Send and not wait for a reply
    • Request Response - Send single request and expect single reply
    • Request Stream - Send single request and expect stream of responses.
    • Request bidirectional - send stream of requests and expect stream of responses.
  • Built-in failure detection, fault tolerance, and elasticity
  • Routing and balancing strategies for both stateless and stateful services
  • Embeddable into existing applications
  • Natural Circuit-Breaker via scalecube-cluster discovery and failure detector.
  • Support Service instance tagging.
  • Support Service discovery partitioning using hierarchy of namespaces in a multi-cluster deployments.
  • Modular, flexible deployment models and topology
  • pluggable api-gateway providers (http / websocket / rsocket)
  • pluggable service transports (tcp / aeron / rsocket)
  • pluggable encoders (json, SBE, Google protocol buffers)
  • pluggable service security authentication and authorization providers.

User Guide:

Basic Usage:

The example provisions 2 cluster nodes and making a remote interaction. 1. seed is a member node and provision no services of its own. 2. then microservices variable is a member that joins seed member and provision GreetingService instance. 3. finally from seed node - create a proxy by the GreetingService api and send a greeting request.

// service definition
public interface GreetingsService {
      Mono sayHello(String name);
// service implementation
public class GreetingServiceImpl implements GreetingsService {
 public Mono sayHello(String name) {
   return Mono.just(new Greeting("Nice to meet you " + name + " and welcome to ScaleCube"));

//1. ScaleCube Node node with no members (container 1) Microservices seed = Microservices.builder() .discovery("seed", ScalecubeServiceDiscovery::new) .transport(RSocketServiceTransport::new) .startAwait();

// get the address of the seed member - will be used to join any other members to the cluster. final Address seedAddress = seed.discovery("seed").address();

//2. Construct a ScaleCube node which joins the cluster hosting the Greeting Service (container 2) Microservices serviceNode = Microservices.builder() .discovery("seed", ep -> new ScalecubeServiceDiscovery(ep) .membership(cfg -> cfg.seedMembers(seedAddress))) .transport(RSocketServiceTransport::new) .services(new GreetingServiceImpl()) .startAwait();

//3. Create service proxy (can be created from any node or container in the cluster) // and Execute the service and subscribe to incoming service events .sayHello("joe").subscribe(consumer -> { System.out.println(consumer.message()); });

// await all instances to shutdown. Mono.whenDelayError(seed.shutdown(), serviceNode.shutdown()).block();

Basic Service Example:

  • RequestOne: Send single request and expect single reply
  • RequestStream: Send single request and expect stream of responses.
  • RequestBidirectional: send stream of requests and expect stream of responses.

A service is nothing but an interface declaring what methods we wish to provision at our cluster.

public interface ExampleService {

@ServiceMethod Mono sayHello(String request);

@ServiceMethod Flux helloStream();

@ServiceMethod Flux helloBidirectional(Flux requests); }


Available api-gateways are rsocket, http and websocket

Basic API-Gateway example:

        .discovery(options -> options.seeds(seed.discovery().address()))
        .services(...) // OPTIONAL: services (if any) as part of this node.

    // configure list of gateways plugins exposing the apis
    .gateway(options -> new WebsocketGateway("ws").port(8080)))
    .gateway(options -> new HttpGateway("http").port(7070)))
    .gateway(options -> new RSocketGateway("rsws").port(9090)))


    // HINT: you can try connect using the api sandbox to these ports to try the api.


With scalecube-services you may plug-and-play alternative providers for Transport,Codecs and discovery. Scalecube is using ServiceLoader to load providers from class path,

You can think about scalecube as slf4j for microservices - Currently supported SPIs:

Transport providers:

  • scalecube-services-transport-rsocket: using rsocket to communicate with remote services.

Message codec providers:

  • scalecube-services-transport-jackson: using Jackson to encode / decode service messages.
  • scalecube-services-transport-protostuff: using protostuff to encode / decode service messages.

Service discovery providers:

  • scalecube-services-discovery: using scalecue-cluster do locate service Endpoint within the cluster

Binaries and dependency information for Maven can be found at

To add a dependency on ScaleCube Services using Maven, use the following:

Maven Central







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