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 as a service-mesh (cluster)
• 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.
• No single-point-of-failure or single-point-of-bottleneck
• Cluster aware and distributed
• Modular, flexible deployment models and topology
• Zero configuration, automatic peer-to-peer service discovery using gossip
• Simple non-blocking, asynchronous programming model
• Resilient due to failure detection, fault tolerance, and elasticity
• Routing and balancing strategies for both stateless and stateful services
• Low latency and high throughput
• Takes advantage of the JVM and scales over available cores
• Embeddable to existing Java applications
• Natural Circuit-Breaker due to tight integration with scalecube-cluster failure detector.
• Support Service instance tagging.
• pluggable service transport
• pluggable encoders

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.

    //1. ScaleCube Node node with no members
    Microservices seed = Microservices.builder().startAwait();

    //2. Construct a ScaleCube node which joins the cluster hosting the Greeting Service
    Microservices microservices = Microservices.builder()
        .seeds(seed.cluster().address()) // some address so its possible to join the cluster.
        .services(new GreetingServiceImpl())
        .startAwait();


    //3. Create service proxy
    GreetingsService service = seed.call().create().api(GreetingsService.class);

    // Execute the services and subscribe to service events
    service.sayHello("joe").subscribe(consumer -> {
      System.out.println(consumer.message());
    });

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);
}

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:

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

Message codec providers:

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

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

 <!-- scalecube apis   -->
 <dependency>
  <groupId>io.scalecube</groupId>
  <artifactId>scalecube-services-api</artifactId>
  <version>2.x.x</version>
 </dependency>
 
 <!-- scalecube services module   -->
 <dependency>
  <groupId>io.scalecube</groupId>
  <artifactId>scalecube-services</artifactId>
  <version>2.x.x</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>rsocket-services-transport</artifactId>
  <version>2.x.x</version>
 </dependency>
 
 <!-- -------------------------------------------
   scalecube message serialization providers:
   ------------------------------------------- -->

 <!-- jackson scalecube messages codec -->
 <dependency>
  <groupId>io.scalecube</groupId>
  <artifactId>scalecube-services-jackson</artifactId>
  <version>2.x.x</version>
 </dependency>

<!-- protostuff scalecube messages codec -->
 <dependency>
  <groupId>io.scalecube</groupId>
  <artifactId>scalecube-services-protostuff</artifactId>
  <version>2.x.x</version>
 </dependency>

 <!-- -------------------------------------------
    scalecube service discovery provider   
   ------------------------------------------- -->
 <dependency>
  <groupId>io.scalecube</groupId>
  <artifactId>scalecube-services-discovery</artifactId>
  <version>2.x.x</version>
 </dependency>