Python web server related knowledge points

1. The process of browser requesting dynamic pages

##2.WSGI

Python Web Server Gateway Interface (or WSGI for short, pronounced "wizgy" ).

WSGI allows developers to separate the web framework of choice from the web server. You can mix and match web servers and web frameworks to choose a suitable pairing. For example, you can run Django, Flask, or Pyramid on Gunicorn or Nginx/uWSGI or Waitress. A true mix and match, thanks to WSGI supporting both server and architecture.

The web server must have a WSGI interface. All modern Python web frameworks already have a WSGI interface, which allows you to use it without modifying the code. The server works together with the featured web framework.

WSGI is supported by web servers, and web frameworks allow you to choose the pairing that suits you, but it also provides convenience for server and framework developers so that they can focus on their preferred areas and expertise without hindering each other. . Other languages ​​have similar interfaces: Java has the Servlet API, and Ruby has Rack.

3. Define the WSGI interface

The WSGI interface definition is very simple. It only requires web developers to implement a function to respond to HTTP requests. Let's take a look at the simplest Web version of "Hello World!":

def application(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/html')])return 'Hello World!'

The above application() function is an HTTP processing function that complies with the WSGI standard. It receives two parameters:

• environ: a dict object containing all HTTP request information;

• start_response: a function that sends an HTTP response.

The entire application() function itself does not involve any HTTP parsing part, that is to say, the underlying web server parsing part and the application logic part are separated, so that developers can You can concentrate on one area. The

application() function must be called by the WSGI server. There are many servers that comply with the WSGI specification. The purpose of our web server project at this time is to make a server that is very likely to parse static web pages and also parse dynamic web pages.

Implementation code:

import time,multiprocessing,socket,os,reclass MyHttpServer(object):def __init__(self):
        serveSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.serveSocket = serveSocket
        self.HTMLPATH = './html'def bind(self,port=8000):
        self.serveSocket.bind(('',port))def start(self):
        self.serveSocket.listen()while True:
            clientSocket, clientAddr = self.serveSocket.accept()
            print(clientSocket)
            multiprocessing.Process(target=self.serveHandler, args=(clientSocket, clientAddr)).start()
            clientSocket.close()def serveHandler(self,clientSocket,clientAddr):try:
            recvData = clientSocket.recv(1024).decode('gbk')
            fileName = re.split(r' +', recvData.splitlines()[0])[1]
            filePath = self.HTMLPATHif fileName.endswith('.py'):try:
                    pyname=fileName[1:-3]# 导入
                    pyModule = __import__(pyname)

                    env={}
                    responseBody = pyModule.application(env,self.startResponse)
                    responseLine = self.responseLine
                    responseHeader = self.responseHeaderexcept ImportError:
                    responseLine = 'HTTP/1.1 404 NOT FOUND'
                    responseHeader = 'Server: ererbai' + os.linesep
                    responseHeader += 'Date: %s' % time.ctime()
                    responseBody = &#39;<h1>很抱歉，服务器中找不到你想要的内容<h1>&#39;else:if &#39;/&#39;== fileName:
                    filePath += &#39;/index.html&#39;else:
                    filePath += fileNametry:
                    file = None
                    file =open(filePath,&#39;r&#39;,encoding=&#39;gbk&#39;)
                    responseBody = file.read()

                    responseLine = &#39;HTTP/1.1 200 OK&#39;
                    responseHeader = &#39;Server: ererbai&#39; + os.linesep
                    responseHeader += &#39;Date:%s&#39; % time.ctime()except FileNotFoundError:
                    responseLine = &#39;HTTP/1.1 404 NOT FOUND&#39;
                    responseHeader = &#39;Server: ererbai&#39; + os.linesep
                    responseHeader += &#39;Date:%s&#39; % time.ctime()
                    responseBody = &#39;很抱歉，服务器中找不到你想要的内容&#39;finally:if (file!=None) and (not file.closed):
                        file.close()except Exception as ex:
            responseLine = &#39;HTTP/1.1 500 ERROR&#39;
            responseHeader = &#39;Server: ererbai&#39; + os.linesep
            responseHeader += &#39;Date: %s&#39; % time.ctime()
            responseBody = &#39;服务器正在维护中，请稍后再试。%s&#39;%exfinally:
            senData = responseLine + os.linesep + responseHeader + os.linesep + os.linesep + responseBody
            print(senData)
            senData = senData.encode(&#39;gbk&#39;)
            clientSocket.send(senData)if (clientSocket!=None) and ( not clientSocket._closed):
                clientSocket.close()def startResponse(self,status,responseHeaders):
        self.responseLine = status
        self.responseHeader = &#39;&#39;for k,v in responseHeaders:
            kv = k + &#39;:&#39; + v + os.linesep
            self.responseHeader += kvif __name__ == &#39;__main__&#39;:
    server = MyHttpServer()
    server.bind(8000)
    server.start()

HTML files existing in the server:

• index.html

<html><head><title>首页-毕业季</title><meta http-equiv=Content-Type content="text/html;charset=gbk"></head><body>我们仍需共生命的慷慨与繁华相爱，即使岁月以刻薄和荒芜相欺。</body></html>

• biye.html

<!DOCTYPE html><html lang="en"><head><meta charset="gbk"><title>毕业季</title></head><body>![](http://localhost:51017/day18/html/biyeji.png)<br>当年以为六月不过也很平常<br>当自己真正经历了毕业<br>才知道偶尔看到六月毕业季等字里所流露的种种想要重温却不敢提及的回忆<br>毕业了<br>那个夏天，我的毕业季，我的青春年少<br>六月<br>有人笑着说解脱，有人哭着说不舍<br>那年，<br>你对我说的你好<br>在不知不觉中<br>变成了<br>再见。</body></html>

biyeji.png

mytime.py file

import timedef application(env,startResponse):
    status = 'HTTP/1.1 200 OK'
    responseHeaders = [('Server','bfe/1.0.8.18'),('Date','%s'%time.ctime()),('Content-Type','text/plain')]
    startResponse(status,responseHeaders)

    responseBody = str(time.ctime())return responseBody

Access results:

Home page

biye.html

##mytime.py

'''
自定义的符合wsgi的框架
'''import timeclass Application(object):def __init__(self, urls):'''框架初始化的时候需要获取路由列表'''
        self.urls = urlsdef __call__(self, env, startResponse):'''
        判断是静态资源还是动态资源。
        设置状态码和响应头和响应体
        :param env:
        :param startResponse:
        :return:
        '''# 从请求头中获取文件名
        fileName = env.get('PATH_INFO')# 判断静态还是动态if fileName.startwith('/static'):
            fileName = fileName[7:]if '/' == fileName:
                filePath += '/index.html'else:
                filePath += fileNametry:
                file = None
                file = open(filePath, 'r', encoding='gbk')
                responseBody = file.read()
                status = 'HTTP/1.1 200 OK'
                responseHeaders = [('Server', 'ererbai')]except FileNotFoundError:
                status = 'HTTP/1.1 404 Not Found'
                responseHeaders = [('Server', 'ererbai')]
                responseBody = &#39;<h1>找不到<h1>&#39;finally:
                startResponse(status, responseHeaders)if (file != None) and (not file.closed):
                    file.close()else:
            isHas = False  # 表示请求的名字是否在urls中，True:存在，False：不存在for url, func in self.urls:if url == fileName:
                    responseBody = func(env, startResponse)
                    isHas = Truebreakif isHas == False:
                status = &#39;HTTP/1.1 404 Not Found&#39;
                responseHeaders = [(&#39;Server&#39;, &#39;ererbai&#39;)]
                responseBody = &#39;<h1>找不到<h1>&#39;
                startResponse(status, responseHeaders)return responseBodydef mytime(env, startResponse):
    status = &#39;HTTP/1.1 200 OK&#39;
    responseHeaders = [(&#39;Server&#39;, &#39;time&#39;)]
    startResponse(status, responseHeaders)
    responseBody = str(time.ctime())return responseBodydef mynews(env, startResponse):
    status = &#39;HTTP/1.1 200 OK&#39;
    responseHeaders = [(&#39;Server&#39;, &#39;news&#39;)]
    startResponse(status, responseHeaders)
    responseBody = str(&#39;xx新闻&#39;)return responseBody&#39;&#39;&#39;路由列表&#39;&#39;&#39;
urls = [
    (&#39;/mytime&#39;, mytime),
    (&#39;/mynews&#39;, mynews)
]

application = Application(urls)

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