实现一个简易的 wsgi 服务器
上文我们介绍了WSGI协议，本文，我们则亲自造一轮字：实现一个wsgi server。我们在模块simple_wsgi实现全部功能，主要包括：
WSGIServer类：实现wigs server功能make_server函数：一个wsgi server工厂函数，用于创建WSGIServer实例。
WSGIServer
WSGIServer类包括一下属性和方法：
- 数据属性：
request_queue_size：类属性，请求连接队列大小listen_socket：监听套接字server_name：服务器名port：服务器端口号client_connection：连接套接字application：web 应用headers_set：响应头部信息request_data：请求报文request_method：请求方法path：请求路径-
request_version：HTTP版本号 -
方法
-
__init__：构造函数 serve_forever：启动服务_parse_request：解析请求_get_environ：构造environ_start_response：构造start_responese函数set_app：调用web application_handle_one_request：处理请求_finish_response：发送HTTP响应
接下来，我们来看看每个方法是怎么实现的。
__init__
def __init__(self, server_address):
# 创建监听套接字
self.listen_socket = listen_socket = socket.socket(
socket.AF_INET,
socket.SOCK_STREAM
)
# 允许地址重用
listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# 绑定本地端点
listen_socket.bind(server_address)
# 被动监听
listen_socket.listen(self.request_queue_size)
# 获取服务器IP地址和端口号
host, port = self.listen_socket.getsockname()[:2]
self.server_name = socket.getfqdn(host)
self.server_port = port
# 响应头部信息
self.headers_set = []
# 其它实例属性
self.application = None
self.client_connection = None
self.request_data = None
self.request_method = None
self.path = None
self.request_version = None
set_app
def set_app(self, application):
"""
设置web应用
:param application:
:return:
"""
self.application = application
serve_forever
def serve_forever(self):
listen_socket = self.listen_socket
while True:
# 连接套接字
self.client_connection, client_address = listen_socket.accept()
# 处理请求
self._handle_one_request()
_parse_request
def _parse_request(self, text):
"""
解析请求行
:param text: http请求报文
:return:
"""
# 获取请求行
request_line = text.splitlines()[0]
request_line = request_line.rstrip('\r\n')
# 获取请求方法、请求URL、Http版本号
(self.request_method,
self.path,
self.request_version
) = request_line.split()
_get_environ
def _get_environ(self):
"""
构建 environ
:return:
"""
env = dict()
# WSGI 变量
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 变量
env['REQUEST_METHOD'] = self.request_method
env['PATH_INFO'] = self.path
env['SERVER_NAME'] = self.server_name
env['SERVER_PORT'] = str(self.server_port)
return env
_start_response
def _start_response(self, status, response_headers, exc_info=None):
# 添加必要的服务器头部信息
server_headers = [
('Date', 'Tue, 31 Mar 2015 12:54:48 GMT'),
('Server', 'WSGIServer 0.2'),
]
self.headers_set = [status, response_headers + server_headers]
_handle_one_request
def _handle_one_request(self):
"""
处理请求
:return:
"""
# 接受数据
self.request_data = request_data = self.client_connection.recv(1024)
# 解析请求行
self._parse_request(request_data)
# 构建环境变量
env = self._get_environ()
# 处理请求，获取响应报文体
result = self.application(env, self._start_response)
# 构建响应报文
self._finish_response(result)
_finish_response
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
self.client_connection.sendall(response)
finally:
self.client_connection.close()
make_server
make_server比较简单，接受一个端点地址和webapplication，返回一个server对象。
def make_server(server_address, application):
server = WSGIServer(server_address)
server.set_app(application)
return server
使用
现在，我们使用刚才完成的simple_wsgi和flask 来开发一个网络应用。代码如下：
# app.py
# coding=utf-8
from simple_wsgi import make_server, SERVER_ADDRESS
from flask import Flask
app = Flask(__name__)
@app.route('/', methods=['GET', 'POST'])
def home():
return '<h1>Home</h1>'
@app.route('/user/<name>')
def user(name):
return '<h1>Hello, %s!</h1>' % name
if __name__ == '__main__':
httpd = make_server(SERVER_ADDRESS, app)
httpd.serve_forever()
这是效果：
It works! 我们居然开发出一个wsgi server！