[cdi-dev] Which version of HttpServletRequest is injected?

[arjan tijms]

Hi,

On Thu, Sep 8, 2016 at 12:40 PM, Martin Kouba <mkouba at redhat.com> wrote:

> that's a good question. In Weld, the request object is captured during
> request context activation, i.e. during ServletRequestListener.requestInitialized()
> notification and before any filter or servlet is invoked. So wrappers are
> ignored and the original/first request is used.
>

Indeed, although do note that some servers (Liberty and WebLogic I think)
send the ServletRequestListener.requestInitialized() notification rather
late, and do that after the application already has seen the request and
has had a chance to wrap it. This by itself is a separate problem. So on
these servers, Weld would receive an early request but not necessarily the
earliest.


> But TBH I don't think we can fix this easily as I'm not aware of any
> portable way to listen for "wrapping actions".
>

This would have to happen with Server specific code I guess, just as Weld
now requires an SPI to obtain the current principal for injection.

You could say that the Servlet container could store the request
"somewhere" on a stack structure, just before it invokes the
ServerAuthModule, Filter, Servlet and anything else I may have forgotten,
and then when control flows back to each Servlet, Filter, etc unwind that
stack.

At the very least the spec for now should perhaps clarify this?

Kind regards,
Arjan Tijms




>
> Martin
>
> Dne 8.9.2016 v 11:02 arjan tijms napsal(a):
>
>> Hi,
>>
>> The CDI spec defines a built-in bean for the type HttpServletRequest. In
>> 3.8 it says:
>>
>> "A servlet container must provide the following built-in beans, all of
>> which have qualifier @Default:
>>
>> a bean with bean type javax.servlet.http.HttpServletRequest, allowing
>> injection of a reference to the HttpServletRequest"
>>
>> An HttpServletRequest however can be wrapped multiple times and by
>> multiple artefacts. I.e. by a ServerAuthModule, Filter and a
>> RequestDispatcher.
>>
>> The question now is; which version of the HttpServletRequest is supposed
>> to be injected?
>>
>> * The first one in the chain?
>> * The last one in the chain?
>> * The current one at a given point in the chain?
>>
>> A little bit of experimenting seems to indicate it's now often "one of
>> the first ones", e.g. the one that happened to be current when e.g. a
>> ServletRequestListener that initialises a specific CDI implementation is
>> called.
>>
>> I think this is a little confusing, as working with an injected request
>> can now totally ignore the request wrapping that has been done and break
>> an application badly.
>>
>> Thoughts?
>>
>> Kind regards,
>> Arjan Tijms
>>
>>
>>
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> --
> Martin Kouba
> Software Engineer
> Red Hat, Czech Republic
>
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