I have a client that connect to server and send all messages of the list, and each message sent, it is deleted from the list.

But when I force to close the server, client still continue sending and deleting messages from the list. I would like that if connection is down, client stop to send messages, or don't delete from list if has no guarantee that server has received the message.

I check that when I sent more than four messages after connection is down, show the error "socket.send() raised exception". But I don't know how to get that error, I think it is asynchronous. Anyway, if I get that error, the error don't happen if the list has less than five messages to sent after connection down.

Ps: I wrote the server just for my tests, but the server I will have no access. So, the client that need to do everything to have the guarantee of data sent.

Thank you so much.

client.py

import asyncio

class Client(asyncio.Protocol):
    TIMEOUT = 1.0
    event_list = []
    for i in range(10):
        event_list.append('msg' + str(i))

    def __init__(self):
        self.client_tcp_timeout = None
        print(self.event_list)

    def connection_made(self, transport):
        print('Connected to Server.')
        self.transport = transport
        self.client_tcp_timeout = loop.call_later(self.TIMEOUT, self.send_from_call_later)

    def data_received(self, data):
        self.data = format(data.decode())
        print('data received: {}'.format(data.decode()))

    def send_from_call_later(self):
        self.msg = self.event_list[0].encode()
        self.transport.write(self.msg)
        print('data sent: {}'.format(self.msg))
        print('Removing data: {}'.format(self.event_list[0]))
        del self.event_list[0]
        print(self.event_list)
        print('-----------------------------------------')
        if len(self.event_list) > 0:
            self.client_tcp_timeout = loop.call_later(self.TIMEOUT, self.send_from_call_later)
        else:
            print('All list was sent to the server.')

    def connection_lost(self, exc):
        print('Connection lost!!!!!!.')

loop = asyncio.get_event_loop()

coro = loop.create_connection(Client, 'localhost', 8000)
client = loop.run_until_complete(coro)

loop.run_forever()

server.py

import asyncio

class Server(asyncio.Protocol):
    def connection_made(self, transport):
        peername = transport.get_extra_info('peername')
        print('connection from {}'.format(peername))
        self.transport = transport

    def data_received(self, data):
        print('data received: {}'.format(data.decode()))
        #self.transport.write(data)

loop = asyncio.get_event_loop()
coro = loop.create_server(Server, 'localhost', 8000)
server = loop.run_until_complete(coro)

print('serving on {}'.format(server.sockets[0].getsockname()))

try:
    loop.run_forever()
except KeyboardInterrupt:
    print("exit")
finally:
    server.close()
    loop.close()

server output (force (CTRL+C) to close server after received msg4):

$ python3 server.py
serving on ('127.0.0.1', 8000)
connection from ('127.0.0.1', 56119)
data received: msg0
data received: msg1
data received: msg2
data received: msg3
data received: msg4
^Cexit

client output

$ python3 client.py 
['msg0', 'msg1', 'msg2', 'msg3', 'msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
Connected to Server.
data sent: b'msg0'
Removing data: msg0
['msg1', 'msg2', 'msg3', 'msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg1'
Removing data: msg1
['msg2', 'msg3', 'msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg2'
Removing data: msg2
['msg3', 'msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg3'
Removing data: msg3
['msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg4'
Removing data: msg4
['msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
Connection lost!!!!!!.
data sent: b'msg5'
Removing data: msg5
['msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg6'
Removing data: msg6
['msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg7'
Removing data: msg7
['msg8', 'msg9']
-----------------------------------------
data sent: b'msg8'
Removing data: msg8
['msg9']
-----------------------------------------
socket.send() raised exception.
data sent: b'msg9'
Removing data: msg9
[]
-----------------------------------------
All list was sent to the server.