...

- need to make sure json2xtc can separate the Names (configure-only)
  from Shapes/Data (l1accept)
- cpo worries about performance of the extra json step
- cpo votes to try dgramcreate approach(with 75% confidence level)

Where Python Runs

1. drp fex (mona/valerio/ric psana python)
2. producing the trigger data (on the drp) (Ric, custom simple data format?)
   1. should this part of the drp fex or a separate subprocess/call?
   2. we can do this with either a python "call" or a subprocess, but "call" can be dangerous because the multi-threaded DRP can get stuck on the GIL: don't do the "call".
3. analyzing the trigger data (on the teb) (Ric, custom simple data format?)
4. python in EbReceiver that uses trigger data results to modify the dgram (e.g. ROI) (mona/valerio/ric psana python) 
   1. use the prescale to record the raw/fex? (but isn't this done by drp fex?)

(1) and (2) could be put into the same psana-python process. (4) is a separate python process.