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From "Eoghan Glynn" <eogl...@progress.com>
Subject RE: why does the SOAP CheckFaultInterceptor run in the POST_PROTOCOL phase?
Date Sun, 16 Nov 2008 13:18:47 GMT

Hi Dan,

I'm open to correction on the security stuff, but I think we might still be OK with the re-ordering
approach even in the presence of whitespace, as the WS-Sec in-interceptor (at least the WSS4J
version anyway) also runs in the PRE-PROTOCOL phase.

So as long as the CheckFaultInterceptor runs near the end of this phase (after the security
interceptor has already validated the signature or whatever), then it should be OK to advance
the XMLStreamReader over any whitespace preceding the first body element. Assuming there's
a test that validates the behaviour on whitespace, I guess this could be easily checked.

However, there is one other case where a simple re-ordering would still seem problematic -
if the response is not a fault to begin with, but one of the JAX-WS SOAPHandlers throws a
ProtocolException and thus changes it to a fault. In that case I guess we'd need to check
again for a fault after the handler chain has been traversed. It might be more straight-forward
to just rerun the (very simple) CheckFaultInterceptor at at a second point in the call chain,
instead of splitting the (relatively complex) JAX-WS interceptor into two parts.

Does that make sense to you?

Cheers,
Eoghan

-----Original Message-----
From: Daniel Kulp [mailto:dkulp@apache.org]
Sent: Fri 14/11/2008 15:26
To: dev@cxf.apache.org
Cc: Eoghan Glynn
Subject: Re: why does the SOAP CheckFaultInterceptor run in the POST_PROTOCOL phase?
 

Actually, I remember why I put it that late.....

The CheckFaultOut stuff HAS to occur after anything related to SAAJ/DOM is 
done.    When it gets there, the XmlStreamReader sits at the first child of 
the soap:body.   However, that might NOT be an element.   It may be 
whitespace.   However, CheckFaultOut has to advance to the first element to 
see it's a fault.  Thus, that whitespace is lost.   That then invalidates any 
signature that may be on the soap body.  You get signature validation issues.   

Since the JAXWS handler interceptor things builds an SAAJ if there isn't 
already one, the CheckFaultOut cannot run before it or the whitespace is 
lost.  

What MIGHT work would be to split the JAXWS handler thing into two parts.   
One that runs real early in the phase chain and if there are handlers, add 
the SAAJInInerceptor and it's second part that does the real work.   That 
second part could then safely assume the SAAJ model is there.   

Dan


On Friday 14 November 2008 11:39:00 am Eoghan Glynn wrote:
> Thanks for the quick response Dan, some comments inline ...
>
> > > Is there any reason why the SOAP CheckFaultInterceptor runs in the
> > > POST_PROTOCOL phase, as opposed to PRE_PROTOCOL?
> >
> > Well, the basic reason is that to check for a fault, it needs to look at
> > the first element in the body.  The headers and envelop and such are
> > handled in the PROTOCOL phase, thus, it needs to be checked afterword.
>
> Sure, but it could do that equally well near the end of PRE_PROTOCOL phase,
> say if its configured to run after the MustUnderstandInterceptor.
>
> Come to think of it though, the ReadHeadersInterceptor runs in the READ
> phase, so we're gauranteed the headers are out of the way by the time
> PRE_PROTOCOL kicks in.
>
> Also, at least in the 2.0.6.x version I'm looking at, once the
> ReadHeaderInterceptors is done, the <SOAP:Envelope> element has already
> been stripped off the XMLStreamReader. So the CheckFaultInterceptor is
> nicely tee'd up to read off the <Fault> element, whether it runs in
> PRE_PROTOCOL or POST_PROTOCOL.
>
> Of course, another option would be to move the JAX-WS handler interceptors
> to the POST_PROTOCOL phase.
>
> > > The net result is handleFault() is never called for a client-side
> > > JAX-WS SOAPHandler, as the CheckFaultInterceptor (which is responbile
> > > for determining if a fault is present in the incoming message) is
> > > assigned to a phase that runs *after* the PRE_PROTOCOL phase in which
> > > the JAX-WS handler chain is traversed. So Handler.handleFault() can
> > > never be called, as it isn't yet known that the message actually
> > > contains a fault.
> >
> > Which MAY be correct.   I'd need to double check the spec and TCK and
> > such. (before committing any change in this area, let me know and I'll
> > run the tck on it).   The handleFault may be for handling faults that are
> > generated as part of processing the normal message.     I'd need to
> > double check on that.
>
> The JAX-WS 2.0/1 specs seems to say little more than:
>
> "9.3.2.2 handleFault
> Called for fault message processing ..."
>
> which seems to imply that handleFault should should be called for a fault
> message on both the client- & server-sides.
>
> Currently in CXF, handleFault is called on a server-side handler for an
> outgoing fault, but handleMessage is called on a client-side handler for
> that same message when inbound. Seems unlikely that this sort of
> inconsistency would actually be intended by the spec. Though stranger
> things have happened, and obviously you were on the spec EG so you'd have
> deeper knowledge of the spec meant to say ... :)
>
> > > So before I go fixing this I wanted to check if this apparent
> > > mis-ordering was just an oversight, or whether there's method to the
> > > madness :)
> >
> > That all said, I've THOUGHT about adding a HttpErrorCodeInterceptor or
> > something that goes very early in the chain to flip it over to the
> > faultInChain if the response code is 500.  That could be done LONG before
> > any processing of anything else is done.   Obviously only useful for HTTP
> > transport though.     The current implementation means that any stream
> > related things only on the faultInChain wouldn't ever get called.  
> > Flipping over based on response code would fix that.
>
> Yeah, that would work ... but as you point out, the restriction HTTP sortta
> makes it a non-runner in the general case.
>
> Cheers,
> Eoghan



-- 
Daniel Kulp
dkulp@apache.org
http://dankulp.com/blog


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