XML Results From Different Data Sources

[Vivek Mehta]

Hi,

I am currently working on a project which requires that our web based
application should allow end user to search on various parts and their
availability in different regions. Http requests will be sent via a
asp/asp.net page to about 10 different databases. The companies which
control these databases will receive requests and send XML resultsets
back. I have limited XML experience and was wondering if some expert
out there can help me with this.
The idea is to present a "combined view" of all the results which will
come back from these 10 different databases. These companies will
agree to a standard XML result set format.

I am not sure how to approach this. I have several questions :
1. Everything needs to happen within a asp/asp.net page.
ASP/ASP.NET Page => Send HTTP Request => Third Party App Processes
Request and spit out XML result set => Our application will render XML
result set to browser

In what form this result set can be obtained from these companies so
that the page can continue on ? Should this XML result set coming back
from third party applications be a physical xml file stored somewhere
on the our server or it should be in memory so that it is just a
matter of parsing
through DOM ?? How should result set be received so it can be parsed
through DOM ? I would really appreciate if someone has a code example
of receiving a result sets from different third party vendors and
processing it in your application to give a combined view of the
information.

2. If a search times out in one database for performance reasons , how
can the search continue in other databases ? How can this be
controlled ?

3. If there are several approcahes of doing this what are the
pros/cons of each approach ?

Sorry for such a long message. Thanks a lot in advance.
Vivek Mehta