websphere application crashes when proxying to site through apache 2.0.47

Background:
An AS/400 on the company network is running websphere 5r1 (soon to be
r2). The developer is creating applications that are to be accessible
from the Internet. He is running an instance of apache on port 80,
using the "WebSphere Plugin" (an interceptor for URLs pointing to one
of the Java applications) and the apps live on port 9080. All this on
the AS/400. Surfing internally to this seems to be working okay.

To provide the outside (Internet) connection I have setup a Linux
server running Apache 2.0.47 with mod_proxy configured thus:

<Proxy *>
Order Deny,Allow
Allow from all
</Proxy>

ProxyPass / http://internal.server.name/
ProxyPassReverse / http://internal.server.name/

When coming into the application from the Internet the homepage loads,
one can get to the application, authenticate and retrieve a page based
on query data entered into the application page.
Then the problem arises: the page returned by the query contains links
to drill down further to specific information. When a user clicks on
one of the links the application blows up, returning a huge websphere
error message, notably:
WF0119: Error occurred while refreshing the screen
and
WF0025: In ControllerRequestHandler.displayScreen(), an exception
occurred while forwarding to /styles/chrome/PageBuilder.jsp

Again, this hasn't happened when running without the (Reverse)Proxy.

Also, running the Apache Plugin (mod_was_ap20_http.so) on the Internet
proxy is not an option as no data may reside on the proxy server and
there are administrative barriers to others manipulating the
plugin-cfg.xml file the plugin requires.

Ideas anyone?

TIA.

> ProxyPass / http://internal.server.name/
> ProxyPassReverse / http://internal.server.name/
>
> When coming into the application from the Internet the homepage loads,
> one can get to the application, authenticate and retrieve a page based
> on query data entered into the application page.
> Then the problem arises: the page returned by the query contains links
> to drill down further to specific information. When a user clicks on
> one of the links the application blows up, returning a huge websphere
> error message, notably:
> WF0119: Error occurred while refreshing the screen
> and
> WF0025: In ControllerRequestHandler.displayScreen(), an exception
> occurred while forwarding to /styles/chrome/PageBuilder.jsp
>
> Again, this hasn't happened when running without the (Reverse)Proxy.

sounds like you're in for some time with a packet sniffer. first do
the action blowing up over the proxy connected directly to the server
and sniff with ethereal on the client. use "follow tcp stream" to see
what is going on. keep a copy of the cleartext. then do the same over
the reverse proxy and keep a copy. then run a sniffer on the reverse
proxy on the backend interface to see what is going to the backend (if
you can't have ethereal on the proxy use tcpdump -i <backend-if> -s
1500 -w dump, copy over dump and read it into etheral for analysis.
then compare all three - look for differences. maybe there's headers
added or missing or data truncated, maybe it's just the fact that
mod_proxy uses no keepalive to the backend.

joachim, who has to do things like thas´t more often than he likes...