Hi,
One issue is when Jersey throws exceptions that are mapped to  
responses, while some of the information is often logged in the server  
log, it is often hard to correlate that with the client as the  
exception appears to be swallowed.
We don't what to place the exception information as a response entity  
as that could interfere with what the client wants to do.
Here are two possible options, when in a "debug" mode e.g. when  
tracing is on:
1) send the exception stack trace as a response header, this could be  
rather large and might cause some clients to barf,
2) send a response header with a URL to where the exception stack  
trace may be obtained. For this we can keep a little in-memory  
resource that holds the information about the request and the  
exception and it can occasionally flush it's state.
Note that we are also considering what is termed a probe in GlassFish  
so that in a running system one can dynamically instrument it and then  
obtain  such exceptions and correlate to a request.
Thoughts?
Paul.