A different approach to Jasper Reports in Rails

Hi All,

I have several intranet applications running on different mongrel
servers.
I want a certain user to be able to design, using iReport, a few
report designs based on XML data from the rails apps.
This user should save these templates to a central location UNC file
based path. The user will publish the report to a Report DB table
that has three (at least) fields: name, path, datasource.

To run the report I want a user to click on a link in a Rails produced
page which downloads a the Report record as XML with a different
mimetype | name | content-type, ie
<report>
  <name>foo</name>
  <path>\\server\share\report-x.jasper(or jrxml)</path>
  <datasource>http://server/app/controller/action</path>
</report>

Jasper Reports will be on each local machine.

I want the browser to spawn an external app because it has been told
to do so for this type of file. The spawned app (maybe local ruby
batch code or java) will take the report template path and datasource
path and generate the report locally and present it with JRViewer or
similar.

This local app spawning bit is what I'm not certain of. I think I
will need to create some Java classes.
Suggestions anyone?

Ta Guy