How to show waiting message while querying backend

[zhuang]

Hi,

There are some articles online showing how to do this. But my scenario
is different, and I could not figure out how to do it at design level.

I developed a web application, which will be called by another web
application, then show the document referenced by the parameters in the
request URL. My web application does not interact with user directlty,
there is no button or any other web control which cause post back.

The back end is a third party software storing PDF, my web application
get the document id from URL and query the third party software to get
the document. The third party software does not cope with many users,
sometimes it takes long time to get the response back. What I want to
do it show some waiting message before the result comes back rather
than just presenting a blank page, some people say, IE got a progress
bar, but it does not satisfy end users, they want waiting message..

Any idea how to achive this?

Thanks

zhuang