repeat-until style processing.

Hi,

  I will explain by an example to illustrate what I am looking for.

  I need to fetch (unknown number of) pages of xml from a webservice.
  Each page contains multiple records, and needs to be processed by an XPL.
  The XPL loops over the nodeset in the page and puts each node in eXist in a separate xml document.

  I can run a command line app, which fetchs one page and stores the xml - that's no problem,
  However if I wish to process an unknown number of pages, I have 2 options.

  1. Run the command line app, switching the page number (http query param) multiple times.
     Obviously this involves invoking the app multiple times and initialization of jvm etc, will be costly.

  2. Run the xpl as an XML-RPC service in Orbeon, and write a perl script to trigger the xpl. The script would know by the response of the XML-RPC service when there is to be no more processing.

  I feel that option 2 is a less costly, but I think it would be a nice-to-have processor in Orbeon.
 
  It would be along the lines of pipeline processor, where calling the sub-pipeline xpl would be repeatedly executed if a "loop-control" directs the repeat.

  I am contemplating writing a custom processor but am not sure how to go about it, and how much time I would need to spend on it.

  Anyone have suggestions?

Thanks.