How to use servlet 3.1 in spring mvc?

Question

There are 2 different features available:

1. servlet 3.0 allows to process request in a thread different from the container thread.

2. servlet 3.1 allows to read/write into socket without blocking reading/writing thread

There are a lot of examples in the internet about servlet 3.0 feature. We can use it in Spring very easily. We just have to return DefferedResult or CompletableFuture

But I can't find example of usage servlet 3.1 in spring. As far as I know we have to register WriteListener and ReadListener and do dome dirty work inside. But I can't find the example of that Listeners. I believe it is not very easy.

Could you please provide example of servlet 3.1 feature in spring with explanation of Listener implementaion ?

Answer 1

For servlet 3.1 you can support non-blocking I/O by using Reactive Streams bridge

Servlet 3.1+ Container

To deploy as a WAR to any Servlet 3.1+ container, you can extend and include {api-spring-framework}/web/server/adapter/AbstractReactiveWebInitializer.html[AbstractReactiveWebInitializer] in the WAR. That class wraps an HttpHandler with ServletHttpHandlerAdapter and registers that as a Servlet.

So you should extend AbstractReactiveWebInitializer which is adding async support

registration.setAsyncSupported(true);

And the support in ServletHttpHandlerAdapter

AsyncContext asyncContext = request.startAsync();