Comment by moe | Hacker News Reader

Comment by moe | Hacker News Reader

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Well, it seems the author drank a bit too much of the webservices kool-aid. HTTP is just one protocol amongst many. It was never meant to be "universal". The only reason why it's being abused for even the most unsuitable tasks nowadays is because when all you have is a hammer then everything starts to look like a thumb...

There are many purposes where HTTP is not suitable at all. Realtime audio/video comes to mind - UDP is commonly used here because even the TCP latency is too much. Anything where you need a persistent, bi-directional connection is not a good match either. Anything where you need to push from server to client. In short: Anything that doesn't fit into the request/response paradigm.

In fact, many consider HTTP in its current incarnation to not even be suitable for the interactivity that we expect of modern webapps.

But ofcourse that doesn't stop the truly enlightened. Hence we got abominations like "Comet", a persistent stream-socket emulated on top of an inherently request/response-based protocol. Or RSS, which is nothing more than Usenet done really, really wrong - all lessons unlearned.

Sorry, got a bit carried away. But you get the idea I guess.

The enthusiasm for tunneling everything over HTTP comes from that being easier than getting firewall rules changed, not any intrinsic properties of HTTP itself. It's port 80 people are interested in, really.

I edited out a section where I talked about how it's NOT just port 80.

It turns out lots of ISPs and broken routers and terrible corporate proxies only allow HTTP. They do things like require HTTP headers, so they can check for whitelists/blacklists. It's stupid and it breaks TCP/IP in general, but most people only care about the internet so it just works for most people.

You mean most people only care about the web, right?

Eep, yes :)

UDP and TCP aren't comparable to HTTP. HTTP is an application layer protocol, which rides on top of UDP and TCP, which are transport layer protocols.

Be careful when you get carried away.

Read my sentence again, I wrote: UDP is commonly used here because even the TCP latency is too much.

I meant to say: They not only avoid HTTP - they even avoid TCP, too.

Well, the phrasing was not ideal, I'll give you that.

http://www.w3.org/Protocols/rfc2616/rfc2616-sec1.html#sec1.4 "HTTP only presumes a reliable transport; any protocol that provides such guarantees can be used"

UDP does not guarantee packet delivery, thus HTTP cannot ride on top of UDP.

I think that entry should have read 'http only presumes a reliable connection based transport'.

It would be pretty hard to make http work over something that guarantees transport of a packet but is not connection oriented.

I stand corrected on that point.

UDP [ Reliable_protocol_wrapper [ HTTP ] ]

Where Reliable_protocol_wrapper does retransmissions, acks, sequence numbering etc.

There's no reason why you couldn't use HTTP over UDP if you like, I'm sure it's most likely been done in the past - if only just for fun.

Actually it can, and does: http://en.wikipedia.org/wiki/HTTPU

HTTPU is not HTTP. That's why it has a different name...

Comet is an abomination if you think the problem is how to design a persistent stream. But the real problem is how to design a persistent stream in the browser.

Well, technically it's an abomination no matter from what angle you look at it (and I am looking at the orbited sourcecode in another window right now).

To me comet is a testament to our collective failure to demand proper tools from the "big guys" (Mozilla, Opera, Microsoft). The term "web 2.0" was coined roughly 7 years ago and even long before that it has been clear that some sort of WebSocket would be incredibly useful to have in a browser.

Yet no single browser vendor (to my knowledge) has impemented it today.

Imagine where we could stand if only Firefox had a true, non-standard Socket class already. People would be using it (socket for the fox, comet-hacks for the rest) and IE market share would probably be dropping faster than ever because all the fancy new apps work better elsewhere.

But I digress, this is mostly whining. You have a point; the comet hack, as ugly as it is, is justified by the lack of proper alternatives. But still, an abomination on so many levels...

I think this exactly illustrates my point... (sorry for calling you out twice moe, I very much appreciate you expressing your opinions even though I disagree with them)

You say "all lessons unlearned" implying that RSS is worse than previous incarnations of solving the same use case. This is a common opinion I really am railing against. RSS is EXTREMELY popular. Usenet is a dying architecture. It's a case where being worse in the "obvious" technical architecture allows you to be better in things that actually matter: ease of access, simplicity of use, lack of installing things and wide support. These are just some of the reasons RSS took off. Easier means more viral, because easier means a shorter viral loop.

Of course, I think RSS is better for syndication than notification, and would prefer more sites like twitter use Webhooks in addition to RSS.

It's a case where being worse in the "obvious" technical architecture allows you to be better in things that actually matter: ease of access, simplicity of use, lack of installing things and wide support.

Well, ubiquity != adequacy. I understood the original author's article as a technical recommendation. He basically suggests to use HTTP for everything because he thinks "it's technically good for everything".

He made broad claims about how any HTTP based protocol will magically scale by leveraging proxies, loadbalancers and other existing infrastructure, completely ignoring the fact that many applications just don't fit into the request/response paradigm in first place.

RSS is a great example for the power of the internet that enables us to "build on what we have" without waiting for some standards body or greater authority to get moving. But it is also a text-book counterexample to his scalability and "one size fits all" claims. Polling just doesn't scale for these things and technically it's a step back from Usenet, that had these problems sorted out already. We went back to square 1 with RSS and are now locked up there until we get a true WebSocket and worthwhile persistent storage in browsers.

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