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Writing a WEB server from scratch | ||||||||
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< < | We do not want to re-invent the wheel and we will use a WEB server already prepared for us by professional programmers but it is nevertheless interesting to implement a very simplistic WEB server ourselves simply to understand the basic principles. | |||||||
> > | We do not want to re-invent the wheel, and we will use a WEB server framework already prepared for us by professional programmers. It is nevertheless interesting to implement a very primitive WEB server ourselves, simply to understand the basic principles. | |||||||
The Hello World WEB Server | ||||||||
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< < | Let's start simple and produce a WEB server that just sends "Hello World!" to the browser when called. You may add some HTML text if desired. In the first version we will write a TCP server creating a stream socket and binding to port 80. | |||||||
> > | Let's start simple and produce a WEB server that just sends "Hello World!" to the browser when called. You may add some HTML text if desired. In the first version we will write a TCP server creating a stream socket and binding to port 80. | |||||||
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM) s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) try: s.bind(('',80)) except OSError as exception: if exception.args[0] = uerrno.EADDRINUSE: print("Socket is already bound, please reset the machine") sys.exit()The server then starts listening for an incoming connection request and establishes a connection by accepting it. s.listen(5) print("Starting the Hello World WEB server on IP address ",ipaddr,"port 80") while True: conn,addr=s.accept() print("GOT a connection from %s" % str(addr)) | ||||||||
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< < | Finally it reads an http request from the connection and answers with its Hello World page: | |||||||
> > | Finally, it reads an HTTP request from the connection and answers with its Hello World page: | |||||||
request=conn.recv(1024) print("Content %s" % str(request)) | ||||||||
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< < | request=str(request) response=html conn.send(response) conn.close() | |||||||
> > | request=str(request) response=html conn.send(response) conn.close() | |||||||
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< < | html is the http string to be sent, e.g. | |||||||
> > | HTML is the HTTP string to be sent, e.g. | |||||||
html = """ <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body> <title>Hello World </title> <h1>The Hello World! HTML page</h1> <p>Hello World!</p> </body> </html> """Please check https://docs.micropython.org/en/latest/library/usocket.html for more details. Here is the complete program: https://afnog.iotworkshop.africa/pub/IoT_Course_English/BasicWEBServer/helloWorldWebServerV1.py.txt -- Uli Raich - 2020-06-08 Comments
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