感觉WSGI确实和SERVLET相似，为PYTHON提供了运行和管理环境。WSGI服务器和PYTHON的WEB框架一起，实现WEB响应。
步骤：
- 首先，服务器启动并加载一个由Web框架/应用提供的可调用的’application’
- 然后，服务器读取请求
- 然后，服务器解析它
- 然后，服务器使用请求的数据创建了一个’environ’字典
- 然后，服务器使用’environ’字典和’start_response’做为参数调用’application’，并拿到返回的响应体。
- 然后，服务器使用调用’application’返回的数据，由’start_response’设置的状态和响应头，来构造HTTP响应。
- 最终，服务器把HTTP响应传回给户端。
代码（别小看它，启动DJANGO的APP都可以的，但DJANGO必须提供一个WSGI供它调用APP）：
# Testedimport socketimport StringIOimport sysclass WSGIServer(object): address_family = socket.AF_INET socket_type = socket.SOCK_STREAM request_queue_size = 1 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 address 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 server host name and port host, port = self.listen_socket.getsockname()[:2] self.server_name = socket.getfqdn(host) self.server_port = port # Return headers set by Web framework/Web application self.headers_set = [] def set_app(self, application): self.application = application def serve_forever(self): listen_socket = self.listen_socket while True: # New client connection self.client_connection, client_address = listen_socket.accept() # Handle one request and close the client connection. Then # loop over to wait for another client connection self.handle_one_request() def handle_one_request(self): self.request_data = request_data = self.client_connection.recv(1024) # Print formatted request data a la 'curl -v' print(''.join( '> {line}n'.format(line=line) for line in request_data.splitlines() )) self.parse_request(request_data) # Construct environment dictionary using request data env = self.get_environ() # It's time to call our application callable and get # back a result that will become HTTP response body result = self.application(env, self.start_response) # Construct a response and send it back to the client self.finish_response(result) def parse_request(self, text): request_line = text.splitlines()[0] request_line = request_line.rstrip('rn') # Break down the request line into components (self.request_method, # GET self.path, # /hello self.request_version # HTTP/1.1 ) = request_line.split() def get_environ(self): env = {} # The following code snippet does not follow PEP8 conventions # but it's formatted the way it is for demonstration purposes # to emphasize the required variables and their values # # Required 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 # Required CGI variables env['REQUEST_METHOD'] = self.request_method # GET env['PATH_INFO'] = self.path # /hello env['SERVER_NAME'] = self.server_name # localhost env[ return env def start_response(self, status, response_headers, exc_info=None): # Add necessary server headers server_headers = [ ('Date', 'Tue, 31 Mar 2015 12:54:48 GMT'), ('Server', 'WSGIServer 0.2'), ] self.headers_set = [status, response_headers + server_headers] # To adhere to WSGI specification the start_response must return # a 'write' callable. We simplicity's sake we'll ignore that detail # for now. # return self.finish_response def finish_response(self, result): try: status, response_headers = self.headers_set response = 'HTTP/1.1 {status}rn'.format(status=status) for header in response_headers: response += '{0}: {1}rn'.format(*header) response += 'rn' for data in result: response += data # Print formatted response data a la 'curl -v' 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) = '', 8888def make_server(server_address, application): server = WSGIServer(server_address) server.set_app(application) return serverif __name__ == '__main__': if len(sys.argv) < 2: sys.exit('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()
def app(environ, start_response): status = '200 OK' response_headers = [('Content-Type', 'text/plain')] start_response(status, response_headers) return ['Hello world from a simple WSGI application!n']
截图：
