HTTP and the Application Layer
HTTP on the wire: what a request and response look like, and what HTTP/2 and HTTP/3 change about the connection under them.
Every layer below delivers bytes; the application layer is where those bytes mean something, and HTTP is the protocol most of them speak. What it looks like on the wire, and what its three versions change underneath, decides how many connections a page opens, why a lost packet slows some sites more than others, and which tool to reach for when a request misbehaves.
The topic places HTTP among the other application protocols, then opens a raw HTTP/1.1 message and separates statelessness from connection lifetime. It follows HTTP/2's many streams on one connection, compares the three versions, and explains why HTTP/3 moves to QUIC over UDP. A gotcha untangles FTP, SFTP and FTPS.
Designing an API on top of HTTP, its methods, status codes and resources, belongs to the API Design subject.
By the end you can read a raw HTTP message, tell statelessness from connection lifetime, say what HTTP/2 and HTTP/3 each fix, and name the protocol for a task.
Contents
10 cardsnot started