ScaleCube is a library that simplifies the development of reactive and distributed applications by providing an embeddable microservices library. It connects distributed microservices in a way that resembles a fabric when viewed collectively. It greatly simplifies and streamlines asynchronous programming and provides a tool-set for managing microservices architecture. ScaleCube is built based on ScaleCube Cluster, which provides a built-in service discovery. The discovery uses SWIM protocol and gossip that scales better and has inherent failure detection and superior coherent understanding of the cluster state and cluster membership taking part in a swarm of services. ScaleCube cluster is a membership protocol that maintains membership amongst processes in a distributed system

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.

• 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:

• Services Overview
• Defining Services
• Implementing services
• Provisioning Clustered Services
• Consuming services

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
@Service("io.scalecube.Greetings")
public interface GreetingsService {
  @ServiceMethod("sayHello")
	  Mono<Greeting> sayHello(String name);
	}
}
// service implementation
public class GreetingServiceImpl implements GreetingsService {
 @Override
 public Mono<Greeting> 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
seed.call().api(GreetingsService.class)
  .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.

@Service
public interface ExampleService {

  @ServiceMethod
  Mono<String> sayHello(String request);

  @ServiceMethod
  Flux<MyResponse> helloStream();

  @ServiceMethod
  Flux<MyResponse> helloBidirectional(Flux<MyRequest> requests);
}

Available api-gateways are rsocket, http and websocket

Basic API-Gateway example:

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

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

        .startAwait();

        // HINT: you can try connect using the api sandbox to these ports to try the api.
        // https://scalecube.github.io/api-sandbox/app/index.html

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. https://github.com/FasterXML
• scalecube-services-transport-protostuff: using protostuff to encode / decode service messages. https://github.com/protostuff

Service discovery providers:

• scalecube-services-discovery: using scalecue-cluster do locate service Endpoint within the cluster https://github.com/scalecube/scalecube-cluster

Binaries and dependency information for Maven can be found at http://search.maven.org.

https://mvnrepository.com/artifact/io.scalecube

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

 <properties>
   <scalecube.version>2.x.x</scalecube.version>
 </properties>

 <!-- -------------------------------------------
   scalecube core and api:
 ------------------------------------------- -->

 <!-- scalecube apis   -->
 <dependency>
  <groupId>io.scalecube</groupId>
  <artifactId>scalecube-services-api</artifactId>
  <version>${scalecube.version}</version>
 </dependency>

 <!-- scalecube services module   -->
 <dependency>
  <groupId>io.scalecube</groupId>
  <artifactId>scalecube-services</artifactId>
  <version>${scalecube.version}</version>
 </dependency>


 <!--

     Plugins / SPIs: bellow a list of providers you may choose from. to constract your own configuration:
     you are welcome to build/contribute your own plugins please consider the existing ones as example.

  -->

 <!-- scalecube transport providers:  -->
 <dependency>
  <groupId>io.scalecube</groupId>
  <artifactId>scalecube-services-transport-rsocket</artifactId>
  <version>${scalecube.version}</version>
 </dependency>

• OM2
• exberry.io

https://exberry.io/career/

https://scalecube.github.io/