Re: [Resteasy-developers] Interceptors

[Ryan J. M. <ry...@da...>]

I like it! And I see where you're going with it. I think this will  
provide a ton of flexibility in the app. I can see a lot of  
opportunities for this kind of feature. How far along are with it?

Ryan-


On Jul 9, 2008, at 6:53 PM, Bill Burke wrote:

> I'm currently prototyping some asynchronous jax-rs based on some of  
> the
> asynchronous talk in the Restful Web Services book.  At first I
> implemented it in a non-abstract fashion.  Just brute force as I  
> wanted
> to see what patterns came up.  After this I realized that I needed  
> some
> form of interception to implement it.  (Mainly because of security).
>
> So, for interception here's some ideas:
>
> * Interceptors will be internal and not supported.  (I want us to  
> write
> a few before we even allow users to try them out).
>
> * interception would happen based on what additional annotation you
> provided: @BeforeUnmarshalling, @AfterUnmarshalling,  
> @BeforeMarshalling,
> and @Aftermarshalling.
>
> * Interceptors will not be called for any subresource locator methods.
>
> * You would be able to use any JAX-RS annotation within the intercept
> method.
>
> * It is an "around" pattern (like EJB's @AroundInvoke
>
> interface RequestContext
> {
>    void invokeNext();
> }
>
> * You must inject and call invokeNext() on a RequestContext or no  
> other
> interceptors will be called, and the request will not be dispatched.
>
> * You will be able to inject the ResourceMethod object so you can get
> preprocessed information about the method you are invoking on
> (annotations, etc...)
>
>
> So here's an example:
>
> @Provider
> @Interceptor
> public class CacheControlInterceptor
> {
>    @BeforeUnmarshalling(@Context HttpRequest request,
>                         @Context HttpResponse response,
>                         @Context RequestContext ctx)
>    {
>       if (isCached(request)) {
>         writeCachedResponse(request, response);
>         return; // don't continue with dispatching
>       }
>       return invokeNext();
>    }
>
>
>    @BeforeMarshalling
>    public void writeCacheControlHeaders(@Context HttpResponse response
>                                         @Context RequestContext ctx)
>    {
>       ... write some cache control headers...
>    }
>
>    @AfterMarshalling
>    public void grabBytesToMarshall(@Context HttpResponse response
>                                    @Context RequestContext) {
>    }
> }
>
>
>
> -- 
> Bill Burke
> JBoss, a division of Red Hat
> http://bill.burkecentral.com
>
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