CODEWITHSUNDEEP
javaservletsasynchronoushttprequesthttpresponse
egerardus
egerardus

Reputation: 11486

Can I check if an async request completed?

Is there any way to check if an async ServletRequest is completed from an AsyncContext? I saw that spring has some kind of wrapper that supports this but googling around I couldn't find anything in the standard library. That is what I was hoping for.

I am using Tomcat 7.

Upvotes: 1

Views: 1720

Answers (2)

Alex Kreutznaer
Alex Kreutznaer

Reputation: 1170

Sounds like one of the two - you either need a listener that will be called upon a asynchronous request completion or you don't need to use an asynchronous call.

Your question is a bit too general.

Talking generally - asynchronous calls are used when the caller is not interested in immediate result of the call. If the caller is interested to know the result of the call immediately then synchronous calls should be used. If the caller is not interested to know the result immediately (for example it has secondary priority, like logging in some business applications), but some action should be performed upon the end of execution of asynchronous calls you should use some sort of a listener.

What you need for asynchronous call is some listener (of class javax.servlet.AsyncListener).

In the listener you will know for sure that the asynchronous call is over (onComplete method) and may perform some action to finalize/complement the asynchronous call.

Again, if you see that the caller of the request needs to know the result upon completion immediately, there probably is a mistake in your architecture. You should use a synchronous call - just wait until the call is done and you will have the result of it. Using an asynchronous call is wrong in this situation.

I saw how people use some sort of a loop to check from time to time the result of a asynchronous call, but it looks like in 99.99% of cases such approach is the result of some architectural mistake.

Upvotes: 3

Ramesh PVK
Ramesh PVK

Reputation: 15446

You can register AsyncListener which can implement onComplete() method.

The AsyncListener needs to be added to the AsyncContext.

Upvotes: 1

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