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From: ram@zedat.fu-berlin.de (Stefan Ram)
Newsgroups: comp.lang.python
Subject: Re: Best (simplest) way to share data
Date: 8 Jul 2024 15:36:57 GMT
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Chris Green <cl@isbd.net> wrote or quoted:
>That's exactly the sort of solution I was wondering about.  Is there a
>ready made module/library for handling this sort of thing?  Basically
>it will just be a string of a few tens of characters that would be
>kept up to date by one process and asked for by all the others.

  I'm not an expert here, and just quickly tried to make it
  run, so the code will still contain errors and not contain
  something necessary, but might give you a starting point.

  A process doing something (here: printing an incrementing value
  named "info") and also serving requests from other processes
  for this "info" value:

import asyncio
import socket

class Server:
    def __init__( self ):
        self.info = 0

    async def handle_client( self, reader, writer ):
        data = await reader.read( 100 )
        message = data.decode()
        addr = writer.get_extra_info( 'peername' )
        print( f"Received {message!r} from {addr}" )

        if message.strip() == "getinfo":
            writer.write( str( self.info ).encode() )
            await writer.drain()

        writer.close()
        await writer.wait_closed()

    async def print_number( self ):
        while True:
            print(  self.info  )
            self.info += 1
            await asyncio.sleep( 1 )

    async def serve( self ):
        server = await asyncio.start_server( self.handle_client, '127.0.0.1', 8888 )
        addr = server.sockets[0].getsockname()
        print( f'Serving on {addr}' )

        async with server:
            await asyncio.gather( server.serve_forever(), self.print_number() )

asyncio.run( Server().serve() )

  , and an example client:

import socket
import time

while True:
    s = socket.socket( socket.AF_INET, socket.SOCK_STREAM )
    s.connect( ( '127.0.0.1', 8888 ))
    s.send( "getinfo".encode() )
    data = s.recv( 100 )
    message = data.decode().strip()
    print( f"Received: {message}" )
    time.sleep( 3 )

  .