Happy to announce that from now Java Reactive Feign client is officially backed by Playtika. All development will be conducted in Playtika fork https://github.com/Playtika/feign-reactive

feign-reactive

Use Feign with Spring WebFlux

Overview

Implementation of Feign on Spring WebClient. Brings you the best of two worlds together : concise syntax of Feign to write client side API on fast, asynchronous and non-blocking HTTP client of Spring WebClient.

Modules

feign-reactor-core : base classes and interfaces that should allow to implement alternative reactor Feign

feign-reactor-webclient : Spring WebClient based implementation of reactor Feign

feign-reactor-cloud : Spring Cloud implementation of reactor Feign (Ribbon/Hystrix)

feign-reactor-rx2 : Rx2 compatible implementation of reactor Feign (depends on feign-reactor-webclient)

feign-reactor-jetty : experimental Reactive Jetty client based implementation of reactor Feign (doesn't depend on feign-reactor-webclient). In future will allow to write pure Rx2 version.

have greater reactivity level then Spring WebClient. By default don't collect body to list instead starts sending request body as stream.
starts receiving reactive response before all reactive request body has been sent
process Flux<String> correctly in request and response body

Usage

Write Feign API as usual, but every method of interface

may accept org.reactivestreams.Publisher as body
must return reactor.core.publisher.Mono or reactor.core.publisher.Flux.

@Headers({ "Accept: application/json" })
public interface IcecreamServiceApi {

  @RequestLine("GET /icecream/flavors")
  Flux<Flavor> getAvailableFlavors();

  @RequestLine("GET /icecream/mixins")
  Flux<Mixin> getAvailableMixins();

  @RequestLine("POST /icecream/orders")
  @Headers("Content-Type: application/json")
  Mono<Bill> makeOrder(IceCreamOrder order);

  @RequestLine("GET /icecream/orders/{orderId}")
  Mono<IceCreamOrder> findOrder(@Param("orderId") int orderId);

  @RequestLine("POST /icecream/bills/pay")
  @Headers("Content-Type: application/json")
  Mono<Void> payBill(Publisher<Bill> bill);
}

Build the client :

/* Create instance of your API */
IcecreamServiceApi client = ReactiveFeign
    .builder()
    .target(IcecreamServiceApi.class, "http://www.icecreame.com")

/* Execute nonblocking requests */
Flux<Flavor> flavors = icecreamApi.getAvailableFlavors();
Flux<Mixin> mixins = icecreamApi.getAvailableMixins();

or cloud aware client :

 IcecreamServiceApi client = CloudReactiveFeign.<IcecreamServiceApi>builder()
    .setFallback(new TestInterface() {
        @Override
        public Mono<String> get() {
            return Mono.just("fallback");
        }
    })
    .setLoadBalancerCommand(
         LoadBalancerCommand.builder()
                 .withLoadBalancer(AbstractLoadBalancer.class.cast(getNamedLoadBalancer(serviceName)))
                 .withRetryHandler(new DefaultLoadBalancerRetryHandler(1, 1, true))
                 .build()
    )
    .target(IcecreamServiceApi.class, "http://" + serviceName);

/* Execute nonblocking requests */
Flux<Flavor> flavors = icecreamApi.getAvailableFlavors();
Flux<Mixin> mixins = icecreamApi.getAvailableMixins();

Rx2 Usage

Write Feign API as usual, but every method of interface

may accept Flowable, Observable, Single or Maybe as body
must return Flowable, Observable, Single or Maybe.

@Headers({"Accept: application/json"})
public interface IcecreamServiceApi {

  @RequestLine("GET /icecream/flavors")
  Flowable<Flavor> getAvailableFlavors();

  @RequestLine("GET /icecream/mixins")
  Observable<Mixin> getAvailableMixins();

  @RequestLine("POST /icecream/orders")
  @Headers("Content-Type: application/json")
  Single<Bill> makeOrder(IceCreamOrder order);

  @RequestLine("GET /icecream/orders/{orderId}")
  Maybe<IceCreamOrder> findOrder(@Param("orderId") int orderId);

  @RequestLine("POST /icecream/bills/pay")
  @Headers("Content-Type: application/json")
  Single<Long> payBill(Bill bill);

Build the client :

/* Create instance of your API */
IcecreamServiceApi client = Rx2ReactiveFeign
    .builder()
    .target(IcecreamServiceApi.class, "http://www.icecreame.com")

/* Execute nonblocking requests */
Flowable<Flavor> flavors = icecreamApi.getAvailableFlavors();
Observable<Mixin> mixins = icecreamApi.getAvailableMixins();

Maven

<repositories>
    <repository>
        <id>bintray-kptfh-feign-reactive</id>
        <name>bintray</name>
        <url>https://dl.bintray.com/kptfh/feign-reactive</url>
    </repository>
</repositories>
...
<dependencies>
    ...
    
    <dependency>
        <groupId>io.github.reactivefeign</groupId>
        <artifactId>feign-reactor-cloud</artifactId>
        <version>1.0.0</version>
    </dependency>
    
    or if you don't need cloud specific functionality
    
    <dependency>
        <groupId>io.github.reactivefeign</groupId>
        <artifactId>feign-reactor-webclient</artifactId>
        <version>1.0.0</version>
    </dependency>
    
    or if you tend to use Rx2 interfaces
    
    <dependency>
            <groupId>io.github.reactivefeign</groupId>
            <artifactId>feign-reactor-rx2</artifactId>
            <version>1.0.0</version>
        </dependency>
    ...
</dependencies>

License

Library distributed under Apache License Version 2.0.