Python JSON-RPC_2.0 TCP服务器客户端说明

Question

I'm having a difficult time fully understanding the nature of a TCP server/client relationship when a JSON string is sent to the server. The information I need may be out there, but I'm perhpas not using the correct search paramaters as I'm looking.

I've built a Python TCP, JSON-RPC Server from the following examples:

• https://github.com/joshmarshall/jsonrpclib
• http://code.activestate.com/recipes/552751-json-rpc-server-and-client/

In both cases, I can communicate with the Python server from a Python console on a different computer, sending commands from one (the client) to the other (server). In all of the examples, I've had to install the libraries mentioned above on both the client and the server machines in order to facilitate the TCP communication.

So the background to my situation and question is, when does JSON enter the mix? This is what I want to do:

Setup a Python TCP server that accepts a JSON string from a remote client inside (or outside) the network. The server parses the JSON string, fetches the method and parameters from the objectified string, and executes the method. The server then sends a JSON string result to the calling client. In this case, the client is a mobile application (iPad, Android, etc) with a JavaScript library that I'll use to send the requests to the server.

Why would I need a Python client? From what I can gather, the client just needs to open a connection to the server and then send the JSON string, right? Why do all the code samples include Python client examples? Are they assuming a server machine is going to talk to a server machine, so they have included client code to help generate the JSON string that will be sent to the server?

If I assume that a Python client isn't really needed for anything, I've been sending JSON strings to the Python server from the iPad, but in each case the server is reporting a "Bad request syntax" error. I'll pen a new question on that issue if I'm understanding the current question correctly.

Insight is appreciated.

Answer 1

The JSON encoding is the lingua franca of your RPC protocol, so you can indeed use any client you like. The implementations you found for JSON-RPC use the HTTP protocol, a very specific communication protocol built on top of TCP/IP, but you can implement the same protocol over raw TCP-IP sockets if so required.

The examples include both the Python client and the server because they illustrate how to implement the JSON-RPC standard in Python, not in JavaScript or C or Lisp. They focus on the implementation in one language. The JSON-RPC standard however, is language agnostic. It doesn't matter what language you write either the server or the client in, as long as they use the same standard.