> From: Jeng Yu [mailto:[EMAIL PROTECTED]
> The servlet (in Appserver A) then processes part of
> the
> form input in the doGet method and then needs to send
> the rest of the form to another web server
> (Appserver B) to process and return the results
> (response code or something) to the calling servlet
> which is waiting for it. The servlet receives the
> results and based on the results, sends
> response back to the client, all within the same doGet
> method.
>
> Is this doable, and What's the best way to go about
> it?
"Best" or "Easiest to code"? :-)
"Best" from a performance point of view is to change your application so that
it's *not* all happening in the same doGet call. You don't know how long your
call will take. You should submit the request via some appropriate mechanism
and return a holding page to the user. Every so often, the holding page should
poll to see whether the call has completed. You'll need some way of storing
the results from appserver B, along with a way of managing timeouts and
similar. Since you've not said how appserver B expects its data, we can't
really suggest specific technologies. This approach minimises the number of
threads that will be waiting at any time.
"Easiest to code" is to use the same doGet call. Be aware that you may tie up
a *lot* of Tomcat threads waiting for responses from B. Your worst case is
when B black-holes at the busiest time for your application, meaning that A has
to wait for a timeout on every call. You'll need at least that many threads
configured unless you want unpleasant error messages returned to your users.
> Should I make the call to Appserver B in a separate
> thread (I'm considering it)?
If you're doing this in the same doGet call, why bother? It's extra overhead
for no good reason - you're already tying up the Tomcat thread for the duration
of the call.
If you're changing your architecture, you'll definitely need to do this.
- Peter
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