Ribbon Module

Ribbon module contains APIs that integrate load balancing, fault tolerance, caching/batching on top of other ribbon modules and Hystrix.

Ribbon Annotations

A Ribbon client can be created from a Java interface annotated with Ribbon annotations, like in the example below. A dynamic proxy is created which translates interface methods invocations into Ribbon requests. Method parameters annotated with @Content annotation are automatically converted into wire format using provided ContentTransformer class. Replies as of now are limited to ByteBuf type only, which contains exact copy of the HTTP response payload. This restrictions are imposed by existing RxNetty capabilities and will be solved once RxNetty serialization framework is complete.

This code snippet is taken from ribbon-examples package and can be found here.

@ResourceGroup(resourceGroupClass = SampleHttpResourceGroup.class)
public interface MovieService {
    @TemplateName("recommendations")
    @Http(method = HttpMethod.GET, uri = "/users/{userId}/recommendations")
    @Hystrix( validator = RecommendationServiceResponseValidator.class,
              fallbackHandler = RecommendationServiceFallbackHandler.class)
    @CacheProviders(@Provider(key = "{userId}", provider = InMemoryCacheProviderFactory.class))
    RibbonRequest<ByteBuf> recommendationsByUserId(@Var("userId") String userId);
    
    @TemplateName("registerMovie")
    @Http( method = HttpMethod.POST, uri = "/movies")
    @Hystrix(validator = RecommendationServiceResponseValidator.class)
    @ContentTransformerClass(RxMovieTransformer.class)
    RibbonRequest<ByteBuf> registerMovie(@Content Movie movie);
}

MovieService movieService = Ribbon.from(MovieService.class);
Observable<ByteBuf> result = movieService.recommendationsByUserId("user1").toObservable();