Keep track of activities

This is a feature request to facilitate the traceability of transactions in 
distributed systems. During the Callimachus Day on February 19th, we discussed 
several solutions:

[10:23] <prototypo> QuentinReul, the only way I can think your request could be 
met would be for clients to provide a custom HTTP header to inform Callimachus 
that multiple requests are part of the same out-of-band transaction and for 
Callimachus to respect that header when it generates its provenance information.
[10:23] <prototypo> There would need to be some way for clients to group 
independent operations into a user-defined group of Callimachus transactions.
[10:37] <prototypo> So, either we could take my earlier approach of having a 
client group transactions by passing an id, or we could have Callimachus 
proactively return a provenance URI so clients could keep track themselves.
[10:37] <prototypo> I have a weak preference for the latter, I think.
[10:37] <QuentinReul> I prefer the former as we do not have to keep mappings, 
but either solution is fine

Original issue reported on code.google.com by devilspa...@googlemail.com on 19 Feb 2013 at 4:53

Thellmann / callimachus

Keep track of activities #42