Question

in the C world, a function can return error code to represent the exit status, and use INOUT/OUT parameter to carry the actual fruit of the process. when it comes to xmlrpc, no INOUT/OUT parameter, is there any best practice/conventions to represent the exit status and actual result?

the context is i am trying to write an agent/daemon (python SimpleXMLRPCServer) running on the Server, and want to design the “protocol” to interact with it.

any advice is appreciated.

EDIT:
per S.Lott’s comment, make the problem more clear.

• it is more about os convention rather
  than C convention. I agree with that.

• the job of the agent is more or less run some cmd on the server, inherently with an exit code/result idiom

.

Answer 1

One simple way to implement this in Python is with a tuple. Have your function return a tuple of: (status, result) where the status can be numeric or a string, and the result can be any Python data structure you fancy.

Here’s an example, adapted from the module documentation. Server code:

from SimpleXMLRPCServer import SimpleXMLRPCServer
from SimpleXMLRPCServer import SimpleXMLRPCRequestHandler

# Restrict to a particular path.
class RequestHandler(SimpleXMLRPCRequestHandler):
    rpc_paths = ('/RPC2',)

# Create server
server = SimpleXMLRPCServer(("localhost", 8000),
                            requestHandler=RequestHandler)

def myfunction(x, y):
    status = 1
    result = [5, 6, [4, 5]]
    return (status, result)
server.register_function(myfunction)

# Run the server's main loop
server.serve_forever()

Client code:

import xmlrpclib

s = xmlrpclib.ServerProxy('http://localhost:8000')
print s.myfunction(2, 4)

The server function returns a tuple