Python Web Server Gateway Interface(WSGI)

import socket,sys
from io import StringIO
class WSGIServer(object):
#ipv4
address_family = socket.AF_INET
#tcp
socket_type = socket.SOCK_STREAM
request_queue_size = 1
recv_size = 1024

def __init__(self,server_address):
#create a listening socket
self.listen_socket = listen_socket = socket.socket(self.address_family,self.socket_type)
#allow to reuse the same port after releasing
listen_socket.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
#bind
listen_socket.bind(server_address)
#activate
listen_socket.listen(self.request_queue_size)
#get listening host full name and port
host,port = self.listen_socket.getsockname()[:2]
self.server_name = socket.getfqdn(host)
self.server_port = port
self.headers_set = []

def set_app(self,application):
self.application = application

def serve_forever(self):
listen_socket = self.listen_socket
while True:
#get new client connection
self.client_connection,client_address = listen_socket.accept()
#handle the request and then close it ro listen the next request
self.handle_one_request()

def handle_one_request(self):
self.request_data = request_data = self.client_connection.recv(self.recv_size)
#print format request data
print(''.join('< {line}\n'.format(line = line) for line in request_data.splitlines()))

#parse the request info
self.parse_request(request_data)
#construct the environment dictionary depend on the request data
env = self.get_environ()
#call the application to construct the response data body
result = self.application(env,self.start_response)
#send the response message to the client
self.finish_response(result)

def parse_request(self,text):
request_line = text.splitlines()[0].rstrip('\r\n')
#break down the request line and get the components needed
self.request_method,self.path,self,request_version = request_line.split()

def get_env(self):
env = {}
#wsgi variables
env['wsgi.version'] = (1,0)
env['wsgi.url_scheme'] = 'http'
env['wsgi.input'] = StringIO.StringIO(self.request_data)
env['wsgi.errors'] = sys.stderr
env['wsgi.multithread'] = False
env['wsgi.multiprocess'] = False
env['wsgi.run_once'] = False
#CGI variables
env['REQUEST_METHOD'] = self.request_method
env['PATH_INFO'] = self.path
env['SERVER_NAME'] = self.server_name
enc['SERVER_PORT'] = self.server_port
return env

def start_response(self,status,response_headers,exc_info=None):
server_headers = [
('Data','Thu,14 Dec 2017 14:55:00 GMT'),
('Server','WSGIServer 0.2'),
]
self.headers_set = [status,response_headers + server_headers]

def finish_response(self,result):
try:
status,response_headers = self.headers_set
response = 'HTTP/1.1 {status}\r\n'.format(status = status)

for header in response_headers:
response += '{0}: {1}\r\n'.format(*header)
response += '\r\n'

for data in result:
response += data

print(''.join('> {line}\n'.format(line = line) for line in response.splitlines()))
self.client_connection.sendall(response)
finally:
self.client_connection.close()

SERVER_ADDRESS = (HOST,PORT) = '',8888

def make_server(server_address,application):
server = WSGIServer(server_address)
server.set_app(application)
return server

if __name__ == '__main__':
if len(sys.argv) < 2:
sys.exit('please provide a WSGI application object as module:callable')
app_path = sys.argv[1]
module,application = app_path.split(':')
module = __import__(module)
application = getattr(module,application)
httpd = make_server(SERVER_ADDRESS,application)
print('WSGIServer:Serving HTTP on port {port}...\n'.format(port=PORT))
httpd.serve_forever()