HTTP(3), Apr/11/2023

Today, I reviewed the HTTP connections.

 

HTTP connections

Non-persistent HTTP

• At most one object sent over TCP connection
  • connection then closed
• Downloading multiple objects required mutiple connections

Persistent HTTP

• Multiple objects can be sent over single TCP connection between client, server.

 

Here is the picture describing Non-persistent HTTP

Without parallel TCP connections

With parallel TCP connections

And this is the Persistent HTTP.

Without Pipelining

With Pipelining

 

 

In the Web server, we have "Conditional GET" which means "don't send object if cache has up-to-date cahced version."

• Cache: specify date of cached copy in HTTP request. --> If-modified-since: <date>
• Server: response contains no object if cached copy is up-to-date --> HTTP/1.0 304 Not modified

Conditional GET