[jax-rs-spec users] [jsr339-experts] Re: WebApplicationException Response entity and exception mappers

From: Sergey Beryozkin <>
Date: Fri, 23 Nov 2012 11:17:27 +0000

On 20/11/12 14:04, Bill Burke wrote:
> On 11/20/2012 5:42 AM, Sergey Beryozkin wrote:
>> Let me summarize.
>> One one hand the spec provides for the optimization in cases where WAE
>> Response entity is not null. On the other hand, this optimization leads
>> to the issue where an application code reports WAE with Response having
>> an entity and also with the cause exception for the benefit of the WAE
>> mapper.
>> I'd like to propose one of the following:
>> 1. Keep the current optimization in place but update the spec to say
>> that "if WAE Response entity is null or WAE cause exception is not null
>> - use the mapper, otherwise - use WAE Response entity directly"
>> 2. Drop the optimization - I'd expect any custom mapper check WAE
>> Response anyway before creating some custom Response instead and
>> dropping this optimization would require a mapper to check if entity is
>> not null - guess most of the mappers do it all the time anyway...
> In Resteasy, we allow you to write a mapper for any exception class, so
> I vote #2.

Me too. I've thought about it more, I can see why the case for the
optimization might work, however the case of supporting the WAE mappers
seeing all WAEs for the purpose of not necessarily converting them to
Responses but its own statistics/logging/etc purposes is stronger IMHO.

It will indeed technically break the BC but at the expectation level
only - the risk though seems pretty minimal and would affect only
mappers not doing proper checks on WAE Response...

It can be recommended at the spec level to get custom WAE mappers to
check that Response entity is not null before trying to do its custom
conversion if any.

Furthermore, I'm assuming this 'expectation' issue can be handled at the
RI level only by introducing a Jersey specific property that can be
enabled to get the optimization still supported in cases where someone
has indeed written a mapper which does immediate conversion without any

So +1 to the 2nd option

Cheers, Sergey