Why IIS support HTTP/2 only through HTTPS and not HTTP ? - iis

When i read the doc, it's look like IIS support HTTP2 only over a TSL connection (https://learn.microsoft.com/en-us/iis/get-started/whats-new-in-iis-10/http2-on-iis - IIS currently supports HTTP/2 only over TLS). Why a such behavior ?

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Can a server using http1.1 protocol be able to serve a request coming from browser using http2 protocol

For example I have a node server which uses the built-in module "http" (which is http1.1 version I assume). So will it be able to serve any XHR request from browser with http2 protocol?
Yes. Browsers negotiate HTTP/2 as part of the HTTPS setup (since browsers only support HTTP/2 over HTTPS). If HTTP/2 is not supported by both sides it will just use HTTP/1.1
Thanks one of the great things about HTTP/2 and why it’s made such headway - the ability to (almost!) seamlessly roll it out to the web without breaking existing sites/servers/browsers.

Confusion http/2,3 and cloudflare

When I start my API server on local it serves http/1.1 but I found that when it's deployed on VPS and set up with Cloudflare, the browser shows the protocol is http/3. So between the clients and Cloudflare is http/3 and Cloudflare and VPS is http/1.1 is this correct? That means http/3 is served only by DNS, my server is still plain http/1.1 and I need to migrate it to http/2 to be truly supported http/2. (I'm using node so it'll be a switch from http to http2 module)
When your web application / web API is behind Cloudflare, Cloudflare acts as a reverse proxy. This means that there are two "legs" of the connection:
From the end user's client (browser / mobile phone etc...) to Cloudflare
From Cloudflare to your origin server (in your case a VPS)
From a user point of view, they see leg (1) so it is quite easy to enable HTTP/2 or HTTP/3 (see documentation) even if your origin server does not support them. This is what you see in the browser when testing, depending on your configuration in the Cloudflare Dashboard.
For leg (2), only HTTP/1.1 is currently supported (as noted also in this Support KB). You can still optimize the setup of that leg by using features such as Argo Smart Routing or Argo Tunnel,
Update Jun 2022: HTTP/2 to the origin server is now supported and can be enabled in the dashboard. See here for more details.

How to force browsers to use HTTP/2 protocol w/o TLS?

I have a nodejs based web app that uses http2 library of nodejs. I start my app
HTTP/2 server is listening on port 3000. PID: 238718.
and want to check app's homepage: http://localhost:3000/
I have an error in Chrome browser: ERR_INVALID_HTTP_RESPONSE
I know that Chrome uses HTTP/2 over TLS (HTTPS).
Does any possibility exist to use HTTP/2 w/o HTTPS in a browsers?
Does HTTP/2 require encryption?
No. After extensive discussion, the Working Group did not have consensus to require the use of encryption (e.g., TLS) for the new protocol.
However, some implementations have stated that they will only support HTTP/2 when it is used over an encrypted connection, and currently no browser supports HTTP/2 unencrypted.
Source: https://http2.github.io/faq/#does-http2-require-encryption
Note that you can just use a self signed certificate for local development

What is difference between httpS and http/2?

I'm trying to understand what is the difference between HTTPS and http/2?
If I'm going to build a Node.js/express app, what should I use?
Can I use HTTPS with http/2?
Maybe if I use HTTPS, I don't need http/2 because it's the same, or HTTPS use http/2 under the hood?
I'm confused.
Someone is linked to me "difference between HTTP 1.1 and HTTP 2.0 [closed]", but I understand the difference between HTTP and HTTP2. I'm asking about HTTPS and HTTP/2
HTTP - A protocol used by clients (e.g. web browsers) to request resources from servers (e.g. web servers).
HTTPS - A way of encrypting HTTP. It basically wraps HTTP messages up in an encrypted format using SSL/TLS. The web is moving towards HTTPS more and more and web browsers are starting to put more and more warnings when a website is served over unencrypted HTTP. Unless you have a very good reason not to, use HTTPS on any websites you create now.
Digging into HTTP more we have:
HTTP/1.1 - this was the prevalent format of HTTP until recently. It is a text-based protocol and has some inefficiencies in it - especially when requesting lots of resources like a typical web page. HTTP/1.1 messages can be unencrypted (where web site addresses start http://) or encrypted with HTTPS (where web site address start with https://). The client uses the start of the URL to decide which protocol to use, usually defaulting to http:// if not provided.
HTTP/2 - a new version of HTTP released in 2015 which addresses some of the performance issues by moving away from a text based protocol to a binary protocol where each byte is clearly defined. This is easier to parse for clients and servers, leaves less room for errors and also allows multiplexing. HTTP/2, like HTTP/1.1, is available over unencrypted (http://) and encrypted (https://) channels but web browsers only support it over HTTPS, where it is decided whether to use HTTP/1.1 or HTTP/2 as part of the HTTPS negotiation at the start of the connection.
HTTP/2 is used by about a third of all websites at the time of writing (up to 50% of websites as of Jan 2020, and 67% of website requests). However not all clients support HTTP/2 so you should support HTTP/1.1 over HTTPS and HTTP/2 over HTTPS where possible (I believe node automatically does this for you when using the http module). I do not believe HTTP/1.1 will be retired any time soon. You should also consider supporting HTTP/1.1 over unencrypted HTTP and then redirect to HTTPS version (which will then use HTTP/1.1 or HTTP/2 as appropriate). A web server like Apache or Nginx in front of Node makes this easy.
HTTP/3 - the next version of HTTP, currently under development. It is expected to be finalised in 2020 though it will likely be late 2020 or even 2021 before you see this widely available in web servers and languages like node. It will be built on top of a UDP-based transport called QUIC (rather than the TCP-based protocol that HTTP/1.1 and HTTP/2 are based on top of). It will include part of HTTPS in the protocol so HTTP/3 will only be available over HTTPS.
In short you should use HTTP/1.1 over HTTPS, should consider HTTP/2 as well if easy to implement (not always possible as not quite ubiquitous yet - but getting there) and in future you might be using HTTP/3.
I suggest you get a firm understanding of all of these technologies (except maybe HTTP/3 just yet) if you want to do web development. It will stand you in good stead.

mod_spdy: Browsers which not support the SPDY protocol

I have a doubt about using module mod_spdy in my webite:
If I install the module mod_spdy in my Apache Server, What will it happen with the http requests come from desktop and mobile browser which not support the SPDY protocol? (see the browser which not support the SPDY protocol in http://caniuse.com/spdy )
I don’t know if in this case Apache will serve the information using the http protocol or the web browser will have problem to render the information. In the last case, is there any solution to solve the problem with the browser that not support SPDY? For instance, use a web server responding with a different protocol (http or SPDY) depending on which user agent is requesting: browsers support SPDY or browsers only support HTTP.
Thanks in advance,
First of all Apache mod_SPDY supports encrypted connection(HTTPS) only, therefore you have to create a VirtualHost for the 443 port and add your SSL certificate. Mod_SPDY will automatically fallback to HTTPS 1.1 if the browser does not support SPDY. A good use for it is to enable server PUSH. Have fun with SPDY!

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