Python JSON Client & Server Redux

The jsocket package is for use during the development of distributed systems. There are two ways to use the package. The first and simplest way is to create a custom single threaded server by overloading the the jsocket.ThreadedServer class. The second, is to use the server factory functionality by overloading the jsocket.ServerFactoryThread class and passing this declaration to the jsocket.ServerFactory(FactoryThread) object. This creates a multithreaded custom JSON server for any number of simultaneous clients.

All of the code can be forked on GitHub here, and the latest release can be installed off PyPi using either “pip install jsocket” or “easy_install jsocket” depending on which python package manager you use.

Using some UML notation you can decipher the inheritance of the jsocket package to be six new module classes and two existing Python classes:

Regardless of which way you choose to use the package, class inheritance is mandatory. As stated above, the simplest way to leverage functionality is to create a custom single threaded server by overloading the ThreadedServer class (just like the ServerFactory class). This is a great way to prototype simple applications in which you want to transfer data in JSON format between a client.

     import jsocket
     import logging
     class MyServer(jsocket.ThreadedServer):
          # This is a basic example of a custom ThreadedServer.
          def __init__(self):
               super(MyServer, self).__init__()
               self.timeout = 2.0

          def _process_message(self, obj):
               # pure virtual method from base class
               if obj != '':
                    if obj['message'] == "new connection":
                         logging.info("new connection.")

     if __name__ == "__main__":
          client = jsocket.JsonClient()
          client.connect()
          client.send_obj({"message": "new connection"})

Albeit brief, the above example creates a server that is capable of acting on JSON data of type “{‘message’: ‘new connection’}”. There are no restrictions on what you declare in the _process_message virtual method. You can think of this as defining your ‘protocol’ for the server.

The second approach is to use the ServerFactory class to create a multithreaded custom JSON server for any number of simultaneous clients. To do this you must inherit from the ServerFactoryThread class. Just like above you need to implement the virtual _process_message method to support your ‘protocol’ (that is, what kind of data you want the server to respond to). After this is done, simply pass the class declaration to the ServerFactory constructor and it does the rest. Whenever the server sees a new client connection it will fork a separate thread of control to manage the interaction with that client (the thread is automatically terminated when the client disconnects).

     import jsocket
     import logging
     class MyFactoryThread(jsocket.ServerFactoryThread):
          # This is an example factory thread, which the server factory will
          # instantiate for each new connection.
          def __init__(self):
               super(MyFactoryThread, self).__init__()
               self.timeout = 2.0

          def _process_message(self, obj):
               # virtual method - Implementer must define protocol
               if obj != '':
                    if obj['message'] == "new connection":
                         logging.info("new connection.")
                    else:
                         logging.info(obj)

     if __name__ == "__main__":
          server = jsocket.ServerFactory(MyFactoryThread)
          server.timeout = 2.0
          server.start()

          #create and connect as many clients as you like here
          client = jsocket.JsonClient()
          client.connect()
          client.send_obj({"message": "new connection"})

          client.close()
          server.stop()
          server.join()

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  1. Pingback: Super Easy Python JSON Client & Server | Christopher Piekarski

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