Web server is mainly known as HTTP Server, which receives HTTP request and send back HTTP response.

We often use express which based on Node.js node:http module to launch a HTTP server, but what's behind them?

source code

Dig one layer more, node:http depends on http:net, which represent a TCP connection.

We can receive bytes from net.createServer, then parse HTTP request message and send back HTTP response message according to RFC2616. When we assume that all data is string, we can easily build a simplest HTTP server.

node http-text/server.js

curl --location --request GET 'http://localhost:8080/' --header 'Content-Type: text/plain' --data-raw 'Hello World'

source code

We still mainly use the code of Simplest HTTP Server.

The only things should be changed is that we cannot treat request body as plain text. We should check Content-Type, and use Content-Length to slice the real part of image bytes data. Then, we can do whatever we want to handle this multi-media data.

node http-image/server.js

curl --location --request GET 'http://localhost:8080/' --header 'Content-Type: image/png' --data-binary './http-image/send.png'