question about pipe advertisements

The commentary in the JXTA Programmer's Guide explains that pipe 
advertisements should keep the same unique id.  It demonstrates this by 
using a pipe advertisement stored in an XML file.

It is unclear to me if the pipe advertisement unique id should be the 
same across my entire JXTA network (that is, the same pipe 
advertisement file on each peer), or if they should be different for 
each peer but stay the same each time a peer is executed.

Stated concretely, which of these should I do:
1) Generate a pipe advertisement file while developing my application, 
and include that in the app's distribution so every peer has the same 
advertisement file, or
2) Generate a pipe advertisement file the first time the app is started 
up, and re-use that on that peer.

thanks!
  -john.