I have to tell i don't work with cRIO or other NI hardware.
As i think, cRIO is the controller which is controlling the other hardware and gathering some measurement data? So package is the result of it work - measurements, common system status or other.
I'll try to explain my architecture. There is the server, the remote devices and the clients of the server.
The remote devices are send the result of their work to the server with POST method.
The remote devices sends the 'sync' request to the server to get any new data from it (commands, etc) with GET method.
The clients get the data from the server using GET method.
The clients send the commands to the server using POST method
Example:
System controlls the doors in the office building.
There are controllers on the doors.
Controllers send the door status (open, closed, broken lock) to the server
Controllers asks the server for commands (lock the door, open the door) - 'sync'
Clients could get the status of all the doors from server
Clients could send the request to open or close some door to the server.
Server forwards this command to the relevant controller with the answer to its 'sync' GET request.
I hope you understand what I have written here and my efforts will not pass in vain