HTTP 308 Incompetence Expected

http://insanecoding.blogspot.com/2014/02/http-308-incompetence-expected.html

by aw3c2 • 12 years ago

234 43 12 years ago

insanecoding.blogspot.com

hk__22• 12 years ago

Side note: don’t use serif fonts such as Georgia with small characters. I changed the font to Helvetica and the readability was much better.

rlongstaff• 12 years ago

Both the font size and colour scheme on that page hurt my eyes.

frou_dh6• 12 years ago

On the plus side, it gave you something to complain about.

rcruzeiro• 12 years ago

Just add this custom css to the page and it should be much more legible:

body { background: white; color: black; line-height: 27px; }

#outer-wrapper { font-family: 'Lucida Grande'; font-size: 11pt; }

kalleboo• 12 years ago

Safari Reader mode to the rescue...

frou_dh6• 12 years ago

Tell the author. This is an aggregator.

hk__22• 12 years ago

The OP might be the author and thus will see this comment. In any case, it can be useful for other people.

lightcatcher• 12 years ago

Can anyone here provide any explanation of how the changes in HTTP2 might not be idiotic?

The changes discussed in the post just seem dumb to me, but I assume there has to be some reasoning behind them.

myhf• 12 years ago

I think the reasoning is "Embrace, Extend, Extinguish"

lvs• 12 years ago

"Veni, vidi, vici."

derefr2• 12 years ago

Alright, think of it this way.

People use HTTP for two things these days:

1. Its originally-stated purpose--an application-layer protocol that allows web browsers to retrive hypermedia documents from web servers. In this usage, HTTP replaced Gopher+FTP.

2. A transport-layer protocol, with features such as identified sub-flows (requests in a pipelined keepalive connection, websockets, etc.), several usefully-different varieties of caching, protocol feature autonegotiation, presentation-layer autonegotiation (Accept headers), automatic redirection semantics, optional encryption (TLS+HSTS+CORS = probably the most well-thought-out security-boundary semantics of any protocol we've got), etc. In this usage, HTTP basically supercedes TCP.

There's a vicious circle here: as HTTP gains traction in sense #2, businesses become increasingly unwilling to allow anything other than HTTP-in-sense-#2 through their firewalls. Eventually, HTTP may be the only transport-layer protocol.

And, given that, on a stance of complete pragmatism where we can't prevent this from happening, only try to make the best of the situation... we need an HTTP-in-sense-#2 that can actually support being used as a universal transport-layer protocol for all of the Internet's traffic.

What does that mean? Well, it means, for one thing, making HTTP lower-overhead (i.e. binary.) It means making HTTP not only work in situations we'd previously have used TCP (e.g. websockets), but also situations where we'd have used UDP (e.g. VoIP streaming.) It means, well, doing pretty much everything HTTP2 does.

Note, though, that HTTP in sense #1 will likely always be around. Nobody who uses HTTP to transfer hypermedia documents between web browsers and web servers needs to switch to HTTP2. HTTP2 can do that, but it isn't for that. (Though, practically, doing HTTP-type stuff over HTTP2 will likely be both faster and more secure.)

andrewflnr3• 12 years ago

None of that explains the changes to redirect codes, which are the main point of the article. Those are what sound truly brain dead.

mattgreenrocks• 12 years ago

Eventually, HTTP may be the only transport-layer protocol.

Worse is better strikes again!

No, seriously; this is terrifying.

e98cuenc• 12 years ago

The author of this article is wrong assuming 301 is used as it is defined by existing standards.

HTTP2 redefines 301 to match current practice (permanent redirect that changes from POST to GET), and defines a new 308 to try again to get a permanent redirect that doesn't change the method.

hobohacker2• 12 years ago

I think the author of this blogpost has a few things off:

- HTTP2 != httpbis. Both work is being done by the same working group "httpbis". http://datatracker.ietf.org/wg/httpbis/charter/ covers this. httpbis (http://stackoverflow.com/questions/9105639/httpbis-what-does...) was originally chartered to revise HTTP/1.1 (RFC2616) The working group will refine RFC2616 to: * Incorporate errata and updates (e.g., references, IANA registries, ABNF) * Fix editorial problems which have led to misunderstandings of the specification * Clarify conformance requirements * Remove known ambiguities where they affect interoperability * Clarify existing methods of extensibility * Remove or deprecate those features that are not widely implemented and also unduly affect interoperability * Where necessary, add implementation advice * Document the security properties of HTTP and its associated mechanisms (e.g., Basic and Digest authentication, cookies, TLS) for common applications

As for the HTTP/2 work, here's a snippet from the charter on that: The Working Group will produce a specification of a new expression of HTTP's current semantics in ordered, bi-directional streams. As with HTTP/1.x, the primary target transport is TCP, but it should be possible to use other transports.

- He seems to think the httpbis folks gratuitously redefined 301. It should be noted that RFC2616 (which, by definition, predates the httpbis work since httpbis is defined to revise RFC2616) had already noted the issue with 301 (http://tools.ietf.org/html/rfc2616#section-10.3.2): Note: When automatically redirecting a POST request after receiving a 301 status code, some existing HTTP/1.0 user agents will erroneously change it into a GET request.

- It's unclear to me whether or not the author acknowledges the existence of buggy implementations as noted in section 10.3.2. It's an open question as to what to do in the presence of buggy implementations. From a server standpoint, if the client is buggy, and you don't want to break the client (willingness to break clients probably depends on how many of the server's users use that client), then you will attempt to work around it, irrespective of what the standard says. Therefore, it's simply pragmatic to ignore the spec if it doesn't mirror reality, and pragmatic spec editors may update the spec to acknowledge this difference.

- As far as current status of the various 308 usages, Julian (author of the 308 draft) is lobbying major user agents to adopt this, and has written up a status update on the Chromium bug tracker: https://code.google.com/p/chromium/issues/detail?id=109012#c....

6cxs2hd62• 12 years ago

It sounds like you're well-marinated in standards bodies, and that's a good thing -- it's tough, often thankless work that someone needs to do.

For the rest of us, the language from OP sure sounds like it's saying, "yeah do whatevs with 301, we give up".

People often read RFCs in a hurry. Wouldn't this be a great place to use the a "SHOULD NOT" (change the request method)?

If you're saying "MUST NOT" would be bad because the horse is out of the barn, I understand. But the draft language now sure sounds like "MAY", and the OP has a good point that it's likely to encourage more wrong behavior, not less.

At least IMHO. Again, I am not a standards lawyer, so please take this feedback accordingly.

hobohacker2• 12 years ago

I guess I should out myself as a Chromium HTTP stack maintainer (since 2009, so this behavior predates me). One might consider me a domain expert here. I participate in IETF HTTPbis for the HTTP/2 work as the primary Chromium representative. I am not involved with the RFC 2616 revision work as that's tough, thankless work, that thank god we have Julian Reschke and Roy Fielding working on. As far as I'm concerned, I owe them a drink everytime I see them. They do an awful lot of legwork talking to various implementations and trying to build consensus on actually conforming with the standard and all its edge cases. It's really quite unfortunate to see this blog post author treat them so unfairly, although I can see how one might easily jump to his conclusion.

Now, as far as "SHOULD NOT", that's a reasonable thought for people not aware of what popular user agents currently do. The thing is, the majority of major browsers rewrite POST to GET on a 301. Here's my browser's code for it: https://code.google.com/p/chromium/codesearch#chromium/src/n.... Here's Firefox's code for it: http://mxr.mozilla.org/mozilla-central/source/netwerk/protoc.... To my knowledge, all browsers implement this behavior. We basically copied IE's behavior, because, IE did it and websites expected all user agents to do what IE did. Story of the web, sound familiar? :P

So, as you can see, Julian was merely acknowledging the pragmatic reality of the situation when he updated the httpbis specs to reflect this behavior: http://trac.tools.ietf.org/wg/httpbis/trac/changeset/1428. And this reasoning behind it is covered in the introduction to the relevant section in the httpbis docs: http://tools.ietf.org/html/draft-ietf-httpbis-p2-semantics-2....

"SHOULD NOT" implies that our implementations are behaving badly. Now, it's true, our implementations may not be behaving ideally from a spec cleanliness point of view, but interop trumps spec cleanliness, at least from the perspective of anyone who actually deploys real software on the internet. So it's probably best for the spec to acknowledge this and officially allow this. Specs that don't mirror reality are...probably not just useless, but actively harmful.

I hope that explains things, cheers.

aprescott3• 12 years ago

While browsers can probably "do anything" with a 301 or 302, I think in practice it's simpler.

I think the issue here is that 301 and 302 were originally intended to preserve the HTTP method but they became permanent and temporary versions of "issue a new request with a GET". So to try and fix that they provided 307 (and now 308) as temporary and permanent versions of "this resource changed location, so reissue this request at the new URL".

I actually wrote a post about this a couple of days before RFC 2616 got marked for official deprecation: https://aprescott.com/posts/http-redirects

I plan on updating that with more information once a proper RFC deprecates 2616 and 308 makes its way into something other than a referenced alternative, as it is in the current draft last time I checked.

Also, for fun, try pointing curl at a server returning various response codes and see what it does with `-X [method]` and compare it with the latest Chrome and Firefox.

6cxs2hd62• 12 years ago

I thought OP said the situation with 301, while not perfect, is much much better than 302. Even if clean-slate 307 and 308 codes is a great idea, I think OP is concerned that redefining 301 to be excessively permissive will make things worse not better -- in that 301 will go from fairly reliable to being as bad as 302.

aprescott3• 12 years ago

302 is already bad, and 301 is already wrongly implement as RFC 2616 itself notes. Ultimately I doubt either is going to see a "fixed" implementation from a buggy one that's lasted as long as it has.

al2o3cr• 12 years ago

One quibble: in re "So now you can use a new status code which older browsers won't know what to do with", I feel pretty confident in saying that "older browsers" won't be talking HTTP2...

Pacabel3• 12 years ago

I feel pretty confident in saying that at least some poorly-written web apps will end up sending new status codes to user agents that are not expecting them.

I also feel pretty confident in saying that it will be the browsers that will be perceived to be "in the wrong" when they reject or ignore such responses, even though it's solely the fault of bad web apps. (See how browsers today need to accept and try to correctly handle totally broken and incorrect markup, for instance.)

mikeash• 12 years ago

I recently attempted to redirect a POST request being made by Apple's NSURLConnection. I say "attempted" because I could not find any status code that didn't make it revert to a GET for the subsequent request. 301, 302, 303, and even 307 didn't work. I finally ended up telling Apache to proxy the request to the real URL rather than trying to redirect the client.

(It is possible to override this behavior in the client with a bit of code, but I was trying to make this work with software that had already shipped.)

ChrisArchitect• 12 years ago

side note: reminded me of some of these 7XX HTTP Status codes - Developer Errors https://github.com/joho/7XX-rfc

HTTP 308 Incompetence Expected

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