Hi,
  We've currently got a system running WebLogic where we accept (http) requests from clients, then pass them to EJBs for basic validation before dispatching them further for asynchronous processing via JMS. The result is returned to the client sometime later via another channel (e.g. email).

  The problem that I've got is that I'd now like to try & make the result of an operation available to the http client, but I've not really got any feel for how this might best be done. The operation I'm initialy looking at takes a few (~3) seconds although others, later, might take more like 30 secs and I don't think I really want to tie up a thread i my appserver for that long if I can help it...

  I'm wondering about a seperate servlet engine, making the request direct to the EJB then listening/scanning a JMS queue for the response, although I'd have to be sure I was able to correctly handle multiple simultaneous actions...

  This doesn't sound too far from web payment gateways, waiting for responses to credit-card authorisations...
Anyone know how they deal/scale with such senarios?

Gwyn