scalecube-services

MICROSERVICES 2.0

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);
}

API-Gateway:

Available api-gateways are rsocket, http and websocket

Basic API-Gateway example:

    Microservices.builder()
        .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(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

Maven

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>

Sponsored by:

• OM2
• exberry.io