HTTP/2 server push

Posted on Posted in New technologies

What is HTTP/2?

HTTP/2 or HTTP 2.0 is a major revision of Hyper Text Transfer Protocol used by World Wide Web. It is second generation of HTTP protocol and a major up-gradation in HTTP since 1997’s HTTP 1.1.

HTTP/2 deals with major 2 issues of HTTP 1.1

1) Head of line blocking (HOL) a performance limiting phenomenon when a line of packets is held up by first packet.
2) Uncompressed Headers


HTTP/2 provides Feature called Server Push
HTTP/2 Server Push allows us to send resources to the user even before he actually requested for them. Server Push is an effective way to save rendering time of web page and achieve performance benefits over HTTP 1.1

What exactly is HTTP/2 Server Push?

Website access uses a request and response mechanism. The user sends request and then a remote server responds with some delay.
Suppose Adam is an internet user and he wanted to visit a website . He entered URL and then the initial request of HTML file is sent to the remote server. This HTML homepage of website is parsed by the web browser where browser encounters need of more resources like CSS files,JavaScript files,images etc.
After Adam requested a homepage his browser puts up a new request for the resources it found in code.  This new request is sent to remote server and with some more time server fulfills this request of additionally resources asked by Adam’s browser.


The problem with this mechanism was that, it requires time for browser to figure out and get the resources it required. After browser discovers what it want it places request and wait for response this all delays page rendering.

This is where Server Push comes in effect. Server Push preemptively push website assets before user explicitly asks it for. Website administrator can plan out and send the resources user may going to need for the page they are requesting.

Suppose user wants to view index.html page where page rendering is highly depend upon the external style-sheet style.css. In simple HTTP protocol after the request for index.html again a new request for style.css will be made by browser but in HTTP/2 we can respond user with index.html with style.css on first request by pushing style.css. This reduces request time which reduces response time and waiting time.So page renders fast compared to HTTP requested page.


Leave a Reply

Your email address will not be published. Required fields are marked *