I tried in the past but gave up since I couldn't figure how to cleanly handle the cookie from the other domain. However if you don't care about the cookie or content from the IIS server you can do this quickly.
I guess you meant Servet Mapping when you said Servlet Filter. All you probably have to do is configure the servlet and servlet-mapping with the URI's that needs to be proxy.
What version of JDK is in use? May be the standard JDK monitoring tools like jstack,jconsole... You need two things to troubleshoot further
- Thread dumps
- GC/Heap Dumps
Yes it's definitely possible to use WebLogic's proxy servlet but bit complicated and documentation is scarce. Any reasons why you can't use Apache's HttpClient besides that you need a additional set of jars?
Did you inspect the properties collection within MessageContext? Type cast the MessageContext contex to appropriate WebSphere implementation class for more details.
I am not sure what parse you want to use. But all the XML parsers API's will support "string" type as well. Below is just an example. You need to look at the API of the parser of you are using.