HTTP/2 - What is it and what is new?

9 Things To Expect

1. Same HTTP APIs

Making HTTP/2 succeed means that it has to work with the existing Web. So, this effort is about getting the HTTP we know on the wire in a better way, not changing what the protocol means.

2. Cheaper Requests

The Web performance community’s mantra is “avoid HTTP requests” because HTTP/1 make them expensive. This has given rise to techniques like inlining, concatenation and spriting to reduce the number of requests on a page.

With HTTP/2, these techniques shouldn’t be necessary

3. Network- and Server-Friendliness

HTTP/2 allows the use of a single connection per host, and encourages sites to consolidate their content on one host where possible.

4. Cache Pushing

HTTP/2’s “server push” allows a server to proactively send things to the client’s cache for future use.

5. Being Able to Change Your Mind

HTTP/2 adds the RST_STREAM frame to allow a client to change its mind; if the browser navigates away from a page, or the user cancels a download, it can avoid having to open a new connection without wasting all of that bandwidth.

6. More Encryption

HTTP/2 doesn’t require you to use TLS (the standard form of SSL, the Web’s encryption layer), but its higher performance makes using encryption easier, since it reduces the impact on how fast your site seems.

7. No More Text

One of the nice things about HTTP/1 is the ability to open up telnet, type in a request (if the server doesn’t time out!) and then look at the response. This won’t be practical in HTTP/2, because it’s a binary protocol. Why?

While binary protocols have lower overhead to parse, as well as a slightly lighter network footprint, the real reason for this big change is that binary protocols are simpler, and therefore less error-prone.

8. It’ll Take Some Time to Get it Right

HTTP/2 isn’t magic Web performance pixie dust; you can’t drop it in and expect your page load times to decrease by 50%.

It’s more accurate to view the new protocol as removing some key impediments to performance; once browsers and servers learn how and when to take advantage of that, performance should start incrementally improving.

9. HTTP/3 and Beyond

HTTP/1.x has lasted for more than fifteen years; why would we be even considering HTTP/3 before HTTP/2 is done?

One of the big reasons that HTTP/2 took so long to get to is that upgrading the protocol in the deployed infrastructure is really hard; there are lots of boxes out there that assume HTTP/1 will never change.

So, if the transition from HTTP/1 to HTTP/2 goes well, it should be a lot easier to introduce the next version, because we can use the same mechanism that we used for the first big hop.

The link below has more information:-

https://www.mnot.net/blog/2014/01/30/http2_expectations