pytcp-message 0.1.9

Client and server for TCP message passing

pytcp_message

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Sends/receives messages in the following format:

| 1 byte         | 8 bytes        |  ... |
| is compressed? | content length | data |

Messages over 575 bytes are automatically compressed/decompressed with zlib

The main classes are TcpServer and TcpClient, which use the above message format to communicate with each other.

TCP response messages are implemented in TcpMessages. TcpMessage has one member, content, which is the bytes content of the message that will be sent. It also includes convenience methods for writing that content to and from a TCP socket using the above format.

TcpServer opens a connection when a request comes in, then listens on that connection until either the client closes the connection or timeout seconds, passed to the constructor, have elapsed. The default is 30. This allows multiple messages to be sent without re-creating new connections.

TCP request messages are implemented using TcpRequests, which inherit from TcpMessage. TcpRequests include an additional member, client_addr, the requester's address.

When a request comes in, TcpServer creates a TcpRequest object with the client's address and content of the incoming message, along with an empty TcpMessage response. These objects are passed to a list of request handlers attached to the server. After all handlers have run, TcpServer sends the TcpMessage response object to the client.

This allows the server to implement a Chain of Responsibility similar to Express/NodeJS. By passing objects to the various handlers, requests and responses can be modified by each method in the chain.

Example:

import time

from pytcp_message import TcpServer, TcpClient
from datetime import datetime

ADDR = "127.0.0.1"
PORT = 8080


def log_request(req, _):
    now = datetime.now().strftime("%F %T")
    print(
        "[{}] {} <-- {}".format(
            now,
            req.get_client_address()[0],
            req.get_content().decode("utf-8")
        )
    )


def send_response(req, res):
    res.set_content("You are {}:{}".format(
        *req.get_client_address()
    ).encode("utf-8"))


def log_response(req, res):
    now = datetime.now().strftime("%F %T")
    print("[{}] {} --> {}".format(
        now,
        res.get_content().decode("utf-8"),
        req.get_client_address()[0]
    ))


def main():
    send_message = "Hello{}"

    tcpd = TcpServer(address=ADDR, port=PORT, timeout=5)
    tcpd.add_request_handler(log_request)
    tcpd.add_request_handler(send_response)
    tcpd.add_request_handler(log_response)

    tcpd.start()
    print("Server running on tcp://{}:{}...".format(ADDR, PORT))

    tcpc = TcpClient((ADDR, PORT))

    for i in range(0, 10):
        print("Client sending '{}'...".format(send_message.format(i)))
        tcpc.send(send_message.format(i).encode("utf-8"))
        response = tcpc.receive()
        print("Client Received: '{}'\n".format(response.decode("utf-8")))

    tcpc.stop()
    print("Client closed connection.")

    tcpd.stop()
    time.sleep(5)
    print("Server stopped.\n")


if __name__ == "__main__":
    main()

Output:

Server running on tcp://127.0.0.1:8080...
Client sending 'Hello0'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello0
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello1'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello1
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello2'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello2
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello3'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello3
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello4'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello4
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello5'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello5
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello6'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello6
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello7'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello7
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello8'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello8
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client sending 'Hello9'...
[2020-06-19 21:01:28] 127.0.0.1 <-- Hello9
[2020-06-19 21:01:28] You are 127.0.0.1:34360 --> 127.0.0.1
Client Received: 'You are 127.0.0.1:34360'

Client closed connection.
Server stopped.