Open Stack

Has anyone ever considered adding the concept of transaction IDs to the 
openstack REST API?

I'm envisioning a way to handle long-running transactions more cleanly. 
  For example:

1) A user sends a request to live-migrate an instance
2) Openstack acks the request and includes a "transaction ID" in the 
response.
3) The user can then poll (or maybe listen to notifications) to see 
whether the transaction is complete or hit an error.

I view this as most useful for things that could potentially take a long 
time to finish--instance creation/deletion/migration/evacuation are 
obvious, I'm sure there are others.

Also, anywhere that we use a "cast" RPC call we'd want to add that call 
to a list associated with that transaction in the database...that way 
the transaction is only complete when all the sub-jobs are complete.

I've seen some discussion about using transaction IDs to locate logs 
corresponding to a given transaction, but nothing about the end user 
being able to query the status of the transaction.

Chris