Python Network Programming: Remote Procedure Calls

The Remote Procedure Call (RPC) system allows you to call functions on a remote server using the same syntax as you would for functions in a local library. This is useful in two situations.

• You can use RPC to leverage the processing power of multiple machines without having to change the code that calls the program on the remote system.
• The data required for the processing is only available on the remote system.

Thus, in Python, we can treat one machine as a server and another as a client, which calls the server to run the remote program. In our example, we will use localhost as both the server and the client.

Running a Server

The Python language has a built-in server that we can run as a local server. The script that runs this server is located in the bin folder of your Python installation and is named classic.py. We can run it from a Python prompt and check that it works as a local server.

python bin/classic.py

When we run the above program, we get the following output −

INFO:SLAVE/18812:server started on [127.0.0.1]:18812

Running a Client

Next, we use the rpyc module to run a client and perform remote procedure calls. In the following example, we execute the print function on the remote server.

import rpyc
conn = rpyc.classic.connect("localhost")
conn.execute("print('Hello from Tutorialspoint')")

When we run the above program, we get the following output −

Hello from Tutorialspoint

Expression Evaluation via RPC

Using the above code example, we can use Python’s built-in functions to execute and evaluate expressions via RPC.

import rpyc
conn = rpyc.classic.connect("localhost")
conn.execute('import math')
conn.eval('2*math.pi')

When we run the above program, we get the following output −

6.283185307179586