esockets

esockets is a python socket.socket server. There are many socket.socket python modules out there, I choose to write this because I failed to find one that met my requirements and at the same time was easy enough to understand. esockets uses non-blocking sockets with select.epoll() to check for read/write/error socket changes.

When to use esockets?

esockets is written for one purpose above all, servers that need to support a high client count. An esockets server client count is restricted by the amount of file descriptors availible on the system.

Important notes about changes

2015-12-15: Changed the name of some of the "on" functions.
2015-12-17: Several choices added when calling ESocketS.Socket()
2015-12-22: Large update, I expect most programs previously built on this module will not work as is anymore
2016-02-14: Updated the readme file

How to get started

Installation

pip install esockets

Update

At the moment (2016-02-14) this module is still new. As I try to integrate it into my other projects I usually find something to improve. So to get the latest version do

pip install esockets --upgrade

See https://github.com/Zaeb0s/epoll-socket-server for the latest changes

Basic setup

The user communicates with the ServerSocket class using two functions (handle_incoming and handle_readable) that returns True/False.

The following is a simple example of an echo server

#!/bin/env python3
import esockets
def handle_incoming(client, address):
    """
    Return True: The client is accepted and the server starts polling for messages
    Return False: The server disconnects the client.
    """
    
    client.sendall(b'SERVER: Connection accepted!\n')
    return True

def handle_readable(client):
    """
    Return True: The client is re-registered to the selector object.
    Return False: The server disconnects the client.
    """
    
    data = client.recv(1028)
    if data == b'':
        return False
    client.sendall(b'SERVER: ' + data)
    return True

server = esockets.SocketServer(handle_incoming=handle_incoming,
                               handle_readable=handle_readable)
server.start()
print('Server started on: {}:{}'.format(server.host, server.port))

Customizable variables

When the SocketServer is initiated the following customizable variables are set if not otherwise specified

Variable	Description	Default
port	The server port	1234
host	The server host	Using the socket modules socket.gethostbyname(socket.gethostname())
queue_size	Max number of clients awaiting to be accepted	1000
block_time	Maximum block time within each selector and queue objects	2
selector	A selectors object to determine which type to use	selectors.EpollSelector
max_subthreads	Maximum number of threads started in addition to the four mainthreads	-1 (Unlimited)
Calling with all default values would then look like this

server = esockets.SocketServer(  port=1234,
                                 host=socket.gethostbyname(socket.gethostname()),
                                 queue_size=1000,
                                 block_time=2,
                                 selector=selectors.EpollSelector,
                                 handle_readable=lambda client: True,
                                 handle_incoming=lambda client, address: True,
                                 max_subthreads=-1):

Planned releases

ewebsockets - A Websocket server based on esockets and the RFC6455 websocket protocol

Contact

Find something hard to understand? Do you have any suggestions of further improvement? If so do not hesitate to contact me on christoffer_zakrisson@hotmail.com