Concurrent Convoy for filename extension only?

I need to matchin two incoming files on their file name extension - which is a timestamp. Such as:

Filename.DAT.<timestamp>
Filename.TOTAL.<timestamp>

This .<timestamp> extension is the only attribute linking the files together.

Obviously I need to create a Parallel or Concurrent Convoy. But how to do this for *part of the filename* or thefilename extension only?

There is a similar issue here

But its not discussed in detail. I dont understand how to "promote" a property using a pipeline? Is it by usinginmsg.Context.Promote ?

Can anyone explain the whole process / steps in detail (except the convoy which I can manage).

[1270 byte] By [CodeDigger] at [2008-1-7]