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

From: Sergey Beryozkin <>
Date: Wed, 14 Nov 2012 10:01:51 +0000

On 13/11/12 19:31, Bill Burke wrote:
> Resteasy you can write an ExceptionMapper for any exception.

Yes, sure, I was just re-reading

(thanks to the user pointing me to it) and apparently the first part of
that section specifically mentions that WAE with non-empty Response
entities are basically not to be submitted to WAE exception mappers:

"If the response property of the exception does not contain an entity
and an exception mapping provider (see section 4.4) is available for
WebApplicationException an implementation MUST use the provider to
create a new Response instance, *otherwise the response property is used

I hope I'm just misreading it.

We've just had another user reporting a temp regression with WAE mapper
not able to see an original cause exception, example:

try {
} catch (BusinessException ex) {
    throw new WebApplicationException(ex);

where a custom WAE mapper is expected to check the cause of the current
WAE and do something with it.

If the above recommendation was indeed about skipping exception mappers
for WAE with non-empty response entities, then all WAE (and subclass)
exception constructors like

"WebApplicationException(Response, Throwable)"

would create WAE instances which would miss custom WAE mappers expecting
to do something with WAE cause exceptions whenever Response entity is
not empty. And I'd consider it a specification bug.

I'd suggest to clarify the listed text, by dropping any references to
WAE and possibly recommend that custom mappers should be aware that the
caught exception's Response entity may not be null though it is up to
them whether to preserve it or not.

Cheers, Sergey

> On 11/13/2012 12:25 PM, Sergey Beryozkin wrote:
>> Hi,
>> CXF user has pointed out that the specification requires that WAE
>> exception mapper is not to be used to map a given WAE to Response if
>> WAE Response entity is not null.
>> Is it what Jersey and RestEasy do ? CXF lets custom WAE mappers manage
>> all WAEs, though of course the custom mapper may choose to somehow
>> modify the original WAE Response entity if any.
>> I'd rather prefer the mappers see all WAEe (and say NotFoundException
>> mappers see all the NFE exceptions, whether or not NFE Response entity
>> is null), example, to make sure all WAE isntances can be given some
>> common treatment like logging them, etc.
>> Sergey