21 — HTTP — asking a web server

HTTP is how programs ask web servers for pages. The example examples/http-client.nme asks your own computer for a file over http://localhost:8000. It is a learning project, not advice.

Serve a folder first, then run the example in a second terminal:

python3 -m http.server 8000

nme run examples/http-client

the server answered: hello from http!

#Steps

1. urllib is a standard Python library, so it needs no installation. The program imports the part that talks to servers and picks a URL:

   # part of examples/http-client.nme
   import urllib.request
   
   url = "http://localhost:8000/hello.txt"
   

   copyrun it →

   localhost means "this computer", and 8000 is the port the server from the first terminal listens on.

2. urlopen opens a connection to that URL and returns a response. The response is not text yet — it is bytes — so it must be read and decoded:

   # part of examples/http-client.nme
   with urllib.request.urlopen(url) as response:
       body = response.read().decode("utf-8")
   

   copyrun it →

   The with block closes the connection when it ends, and .decode("utf-8") turns the bytes into a string.

3. The last line shows the answer. body.strip() removes the newline the server sent with the file:

   # part of examples/http-client.nme
   show "the server answered: " + body.strip()
   

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4. nme check verifies the program even without a server — checking only needs the syntax, running needs the server:

   nme check examples/http-client
   

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5. The Korean twin examples/http-client.ko.nme writes the same program; only the final show becomes 말해 "서버 응답: " + body.strip(). Run nme r examples/http-client.ko against the same folder for the same result in Korean.

#Try it yourself

Add a second file, hello2.txt, to the folder you serve and change url to point at it. Restart nothing — the server reads files on demand — then run the example again to see the new file.

#What you learned

• python3 -m http.server 8000 serves the current folder on localhost:8000.
• urllib.request.urlopen(url) opens a connection and returns a response.
• A response must be read with .read() and decoded with .decode("utf-8").
• body.strip() removes the newline the server sent with the file.