Skip to content

web-reactive.adoc

Latest commit

 

History

History
72 lines (53 loc) · 3.18 KB

web-reactive.adoc

File metadata and controls

72 lines (53 loc) · 3.18 KB
Raw

Web on Reactive Stack

Table of Contents

This part of the documentation covers support for reactive stack, web applications built on a Reactive Streams API to run on non-blocking servers such as Netty, Undertow, and Servlet 3.1+ containers. Individual chapters cover the Spring WebFlux framework, the reactive WebClient, support for Testing, and Reactive Libraries. For Servlet stack, web applications, please see Web on Servlet Stack.

Testing

The spring-test module provides mock implementations of ServerHttpRequest, ServerHttpResponse, and ServerWebExchange. See Spring Web Reactive mock objects.

The WebTestClient builds on these mock request and response objects to provide support for testing WebFlux applications without and HTTP server. The WebTestClient can be used for end-to-end integration tests too.

Reactive Libraries

Reactor is a required dependency for the spring-webflux module and is used internally for composing logic and for Reactive Streams support. An easy rule to remember is that WebFlux APIs return Flux or Mono — since that’s what’s used internally, and leniently accept any Reactive Streams Publisher implementation.

The use of Flux and Mono helps to express cardinality — e.g. whether a single or multiple async values are expected. This is important for API design but also essential in some cases, e.g. when encoding an HTTP message.

For annotated controllers, WebFlux adapts transparently to the reactive library in use with proper translation of cardinality. This is done with the help of the ReactiveAdapterRegistry from spring-core which provides pluggable support for reactive and async types. The registry has built-in support for RxJava and CompletableFuture but others can be registered.

For functional endpoints, the WebClient, and other functional APIs, the general rule of thumb for WebFlux APIs applies:

  • Flux or Mono as return values — use them to compose logic or pass to any Reactive Streams library (both are Publisher implementations).

  • Reactive Streams Publisher for input — if a Publisher from another reactive library is provided it can only be treated as a stream with unknown semantics (0..N). If the semantics are known — e.g. io.reactivex.Single, you can use Mono.from(Publisher) and pass that in instead of the raw Publisher.

Note

For example, given a Publisher that is not a Mono, the Jackson JSON message writer expects multiple values. If the media type implies an infinite stream — e.g. "application/json+stream", values are written and flushed individually; otherwise values are buffered into a list and rendered as a JSON array.