i have a RESTful api application build on spring mvc.
recently i was doing something integration between spring mvc and reactive stream (like rxjava and project-reactor) and try to make the application more reactive.
i have just build some demo like this below:
1.for rxjava,i use PublishSubject
private SerializedSubject<StreamResult, StreamResult> subject = PublishSubject.<StreamResult>create().toSerialized();
public ReactiveStreamController() {
this.subject.subscribe(streamResult -> {
String id = streamResult.getRequest().getParameter("id");
System.out.println("[" + Thread.currentThread().getName() + "] request received. id = " + id);
String random = StringUtils.isBlank(id) ? StringUtils.EMPTY : id;
ResponseVO vo = new ResponseVO(200, "success = " + random);
streamResult.getFuture().complete(vo);
}, Throwable::printStackTrace);
}
@ResponseBody
@RequestMapping(value = "/rxJava", method = RequestMethod.GET)
public CompletableFuture<ResponseVO> rxJavaController(HttpServletRequest httpServletRequest) {
StreamResult sr = new StreamResult();
sr.setRequest(httpServletRequest);
subject.onNext(sr);
return sr.getFuture();
}
2.for project reactor
@ResponseBody
@RequestMapping(value = "/reactorCodeNew", method = RequestMethod.GET)
public CompletableFuture<ResponseVO> reactorCoreNewParadigm(HttpServletRequest servletRequest) {
Mono<ResponseVO> mono = Mono.just(servletRequest)
.subscribeOn(executorService)
.map(request -> {
String id = request.getParameter("id");
System.out.println("[" + Thread.currentThread().getName() + "] request received. id = " + id);
String random = StringUtils.isBlank(id) ? StringUtils.EMPTY : id;
ResponseVO vo = new ResponseVO(200, "success = " + random);
return vo;
})
.timeout(Duration.ofSeconds(2), Mono.just(new ResponseVO(500, "error")));
return mono.toCompletableFuture();
}
while running both the demos, i don't quite see too many difference between just using a java's CompletableFuture to supply among the controller method.
what i understand reactive stream and what i want is treating the servlet request as a stream and cosume it with some feature like backpressure.
i wanna know: 1. is there a better way to make the application more reactive? 2. is it correct or compatible to integrate spring mvc with reactive streams? if yes, how can i performce feature like backpressure?
i realize maybe i forgot to declare why/how i return a completablefuture in the controller, actually i inject a customized MethodReturnValueHandler to transform the CompletableFuture to DefferdResult.
public class CompletableFutureMethodReturnValueHandler extends DeferredResultMethodReturnValueHandler {
@Override
public boolean supportsReturnType(MethodParameter returnType) {
return CompletableFuture.class.isAssignableFrom(returnType.getParameterType());
}
@Override
public void handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
CompletableFuture<?> completableFuture = (CompletableFuture<?>) returnValue;
super.handleReturnValue(CompletableDeferredResult.newInstance(completableFuture), returnType, mavContainer, webRequest);
}
}
