[errai-dev] Client interceptors - jax-rs

Eric Wittmann eric.wittmann at redhat.com
Tue Feb 11 13:27:21 EST 2014


OK I have a pull request for this.  I ended up with a separate proposed 
implementation that was much easier to execute.  Namely there is a new 
annotation @InterceptsRemoteCall that references the interfaces that 
should be intercepted.  This annotation is applied to the interceptor 
class itself.  So something like this:

@InterceptsRemoteCall({ RemoteOne.class, RemoteTwo.class })
public class MyInterceptor implements RestClientInterceptor {

     @Override
     public void aroundInvoke(RestCallContext context) {
         context.getRequestBuilder()
                .setHeader("X-Custom-Header", "Custom Value");
         context.proceed(); // must be called to continue chain
     }

}

This solves the core problem of being able to intercept calls to remote 
interfaces without modifying (annotating) those interfaces.

Pull request:  https://github.com/errai/errai/pull/80

The PR does *not* include any Interceptor + IOC enhancements.  I have a 
proposal for that and will email it out separately.

-Eric

On 2/9/2014 7:03 PM, Christian Sadilek wrote:
> Yes, I think this is what it should look like. However, we have to make sure errai-bus and errai-jaxrs (both support client-side interceptors) can be used without errai-ioc. We have people in the community using these modules with alternative IOC providers (GIN).
>
> This is something we have to consider when implementing this especially in regards to interceptor instances being managed beans. We now have a way to determine (at rebind time) whether or not errai-ioc was inherited. So, we could generate different code if that's the case.
>
> Cheers,
> Christian
>
> On 2014-02-07, at 3:11 PM, Eric Wittmann <eric.wittmann at redhat.com> wrote:
>
>> I think I'm a fan of option #2.  To be clear, would it look like this (for example)?
>>
>> @Templated
>> @Page(path="dashboard", role=DefaultPage.class)
>> @Dependent
>> public class DashboardPage extends AbstractPage {
>>
>>     @Inject
>>     @Interceptors({ AuthInterceptor.class, ReqHeaderInterceptor.class })
>>     private Caller<IMyRestService> caller;
>>
>> }
>>
>> That seems pretty slick to me.  It does mean that if I inject that Caller in multiple places I need to specify the interceptor list each time.  But that actually sounds pretty powerful to me.
>>
>> Would the interceptors be managed beans (i.e. injected into the Caller)?  My use case would be that I'd have an AuthenticationInterceptor for my Caller, but I would want to @Inject a configuration bean of some kind into it, because I might be using either BASIC auth *or* Bearer Token auth, and the managed configuration bean is what knows which it is.
>>
>> -Eric
>>
>> PS: adding the errai-dev list to the conversation, which is what I should have done originally
>>
>> On 2/7/2014 11:35 AM, Christian Sadilek wrote:
>>> Yeah, I had thought about that as well before but couldn't decide what's best:
>>>
>>> - Add a mapping to ErraiApp.properties
>>> - Add an annotation/qualifier @Interceptors(...) that can be used when injecting a Caller<?>
>>> - Add a parameter to call() that takes a List of interceptors
>>>
>>> Definitely a good feature to have. Wdyt?
>>>
>>> Cheers,
>>> Christian
>>>
>>> On 2014-02-07, at 10:06 AM, Eric Wittmann <eric.wittmann at redhat.com> wrote:
>>>
>>>> I was reading the documentation re: client interceptors for jax-rs in Errai and I was wondering what you thought about adding a mechanism to allow client interceptors to be defined either globally or in some way that doesn't require modifying the JAX-RS interface (to add annotations).  I'm thinking that in some cases a developer might be creating a UI and invoking REST services where they have access to the jax-rs interfaces but do not have write privs.  In other words they can consume them but not modify them.  In that case it might be nice to able to apply interceptors in some other way.
>>>>
>>>> Thoughts?
>>>>
>>>> -Eric
>>>
>


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