question on sub-requests

Hi.

context: Apache2.x, mod_perl 2.x

In response to some request URLs, I have to compose a response structured as follows :

- a html frameset document with two frames
- in the 1st frame, the result of another HTTP request to the same Apache server.
   This URI of this HTTP request is created by "mangling" the original request URL somewhat.
- in the 2d frame, the content of the HTML file corresponding to the original request URI.

For example, if the original request URI was something like : "/abc/def/ghi.html", then
   - the top frame should contain the (html) output of a request to 
"/cgi-bin/mangle.pl?arg=ghi"
   - the bottom frame should contain the content of the originally-requested 
"/abc/def/ghi.html" URI (which is a static file).

I am thinking of doing this by :
- creating a mod_perl ResponseHandler
- having this response handler make a first sub-request to the 
"/cgi-bin/mangle.pl?arg=ghi" URI, grabbing the content of the response to that 
sub-request, and insert it into the first <frame> of the output <frameset> document.
- having the response handler do a lookup_uri of the original URI, get the resulting 
filename, reading the file and insert its content into the second <frame> of the output 
<frameset> document.

My 1st question is : is the above a valid plan, or is there something fundamentally wrong 
with this approach ?

My 2d question is : looking at the Apache2::SubRequest documentation, I do not see a clear 
way of getting the response content of a subrequest.  For example, the run() method 
explanation seems to indicate that the response content is sent directly to the client.
Am I missing something ?

TIA