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  2. Providers ordering

Re: Providers ordering

Sergey Beryozkin
 

Continuing with the idea of the special treatment of the providers shipped with the spec implementations.
Rather than pursue a @DefaultProvider idea, how about treating the providers in the javax.* namespace as 'default' ones ?

Thus if say an MVC API ships its own CSRF exception mapper then it will be selected, unless the application has registered its own.

Moreover, perhaps this idea and the idea of using @Priority are not mutually exclusive. IMHO the former puts less 'pressure' on the application providers to make it right...

Sergey

On 21/05/17 16:19, Sergey Beryozkin wrote:
Hi Christian

Right, do you mean that both of these providers are custom as far as the JAX-RS implementation is concerned ?

Sure, I see what you mean now.

I guess my only doubt at this stage is, should the providers offered by MVC implementation (or some other *spec-implementaion* API) have a special treatment status, as far as JAX-RS is concerned ? Example, be annotated with some @DefaultProvider annotation (to be introduced in JAX-RS) ? In this case JAX-RS, seeing two MyObject exception mappers, will select the one which has no @DefaultProvider.

May be using @Priority is simpler, but it would require application mappers to know how to set their own @Priority to ensure it is high or low enough. The problem with @DefaultProvider is that it is probably too late as ex MVC API would need updated after 2.1 is out.

Cheers. Sergey

On 21/05/17 15:58, Christian Kaltepoth wrote:
Hi Sergey,

By the way, what is the actual point of ordering say 2 ExceptionMapper<MyObject> - would it go a bit too far without bringing any real benefit ?

Of course nobody will want to create two ExceptionMapper<MyObject> implementations in his application. It is more about the case that some framework provides a "default" exception mapper for a specific exception type and the developer should still be able to provide a custom one which is preferred by the JAX-RS implementation.

We had this case in JSR-371 (MVC 1.0): If the validation of a CSRF token fails, the MVC implementation throws a CsrfValidationException. The MVC implementation provides a default mapper ExceptionMapper<CsrfValidationException> which just sends a 403 status code. But the developer should be able to provide a custom exception mapper which does something else, like rendering some HTML page. However, this is currently not possible, because if there are two ExceptionMapper<CsrfValidationException> implementations discovered, there is no way to tell the JAX-RS implementation which one to choose.

Christian



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Christian Kaltepoth
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