Support an asynchronous API for RestTemplate [SPR-8804]

[spring-projects-issues]

Mike Youngstrom opened SPR-8804 and commented

Asynchronous programming models are growing in popularity. To support this model of development it would be great if RestTemplate were enhanced to support an asynchronous model.

JAX-RS's client api is currently slated to add an asynchronous mode.

There are several Async Http client libraries.

It would seem that soon would be the right time to add Async support for RestTemplate.

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Referenced from: commits 296e218, ebcee26, 20c4177, 38c8c6d

12 votes, 19 watchers

[spring-projects-issues]

Chris Beams commented

Thanks for the submission, Mike. I've added Juergen, Arjen and others as watchers on this issue and slated it for the 3.2 backlog. Agreed that 3.2 is likely the right time to consider such functionality; I'll be interested to see what other users have to say about this as well. Use cases would be helpful to ensure we're all on the same page.

[spring-projects-issues]

Lukas Krecan commented

We have similar need. Our use case is simple. We are creating an aggregated resource. We need to call several underlying REST APIs and when all of the results return, we merge them to return aggregated result. We want to execute all the requests in parallel. So the ideal API would be

Future result1 = execute(...);
Future result2 = execute(...);
Future result3 = execute(...);

merge(result1, result2, result3);

[spring-projects-issues]

Chris Beams commented

Added @Rossen as a watcher as well as he's currently investigating async options in 3.2

[spring-projects-issues]

Lukas Krecan commented

I have written a quick prototype of AsyncRestTemplate lukas-krecan@1f55c1b. Basically it wraps RestTemplate, executes the corresponding method using AsyncTaskExecutor and returns Future instead of the original return value. Please let me know what you think about it. If you are interested, I will fix the documentation, formating, tests and other stuff and will issue a pull request.

[spring-projects-issues]

Rossen Stoyanchev commented

Yes, that will certainly be one part of the implementation. We'll also want to support HTTP libraries that provide non-blocking support like Appache HttpComponents HttpAsyncClient.

[spring-projects-issues]

Lukas Krecan commented

Do you have any update whether it will make it to Spring 4?

[spring-projects-issues]

Arjen Poutsma commented

It will make it :).

[spring-projects-issues]

Arjen Poutsma commented

Pull request at #336

[spring-projects-issues]

Luciano Leggieri commented

Do you think it's worth to add support for https://github.com/AsyncHttpClient/async-http-client ? It's a popular framework for non-blocking connections.
I have a first draft here: https://github.com/lukiano/async-http-client-spring