HttpProxyServlet - need run-time config NOT deploy-time

Question

          HI,
          I've looked through a lot of the traffic and haven't seen
          anything along the lines of this question. I have a system
          which we compile and build and then start up in a specific
          mode (i.e. production, development etc). All of the config is
          done at application startup time (the config.xml file is dynamically generated).
          The problem is that when configuring the
          web.xml for the HttpProxyServlet we must enter in a URL for the
          redirect to go to. What I really want to do is along hte lines
          of entering in a property-name, the value of which will give me
          the URL, i.e. instead of:
          <servlet>
          <servlet-class>
          weblogic.t3.srvr.HttpProxyServlet
          </servlet-class>
          <init-param>
          <param-name>redirectURL</param-name>
          <param-value>http://myRedirectPort</param-value>
          </init-param>
          </servlet>
          I would like to do something like this :
          <servlet>
          <servlet-class>
          com.myapp.HttpProxyServlet
          </servlet-class>
          <init-param>
          <param-name>redirect-url-property-name</param-name>
          <param-value>
          my-prop-name.redirect-url
          </param-value>
          </init-param>
          </servlet>
          With the second one I would then pass in the property:
          -Dmy-prop-name.redirect-url=http://myRedirectPort
          Which would give me "run" (not deploy/build) time configuration
          of this URL.
          My question is:
          1. Has anyone done anything like this before ?
          2. Has anyone any knowledge/experience of subclassing the
          weblogic.t3.srvr.HttpProxyServlet ?
          3. Is there any way to do this type of thing in weblogic ?
          4. Would it be easier to write my own proxy servlet ?
          Any pointers to same appreciated.
          5. Is it programmatically easy/possible to register the
          HttpProxyServlet in my own hand written servlet.
          Any help very much appreciated.
          I have cross posted this because I think it is partly,
          environment, install based and partly servlet based.
          Thanks,
          Brian
          

Answer 1

7) Miscellaneous Stuff 
A) Error Messaging
If the Enhanced DSC Run Time is required but you do not check it in the build spec I got the following errors on running the application:
The messages are not informative at all.
Can't this be handling automatically?
Can't this get flagged earlier when you are building?
B) Build Error
This one may or may not be DSC specific, but the following type of Build Errors are not very helpful: 
C) Build Spec Info
Something I noticed - the Build Spec contains no info about it. 
All the other options do.
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