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Comment by pohl | Hacker News Reader

Why are people calling URL fragment a "hashbang" now? The exclamation point is only as recent as Google's Ajax spider standard proposal.

(Is the present essay only concerned about the strict subset of navigation state encoded in fragments that seeks to be indexed by spiders? Or is it concerned about all such usage and is abusing the term "hashbang"?)

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Because the convention as used by Gawker and similar is not about referencing an anchor but describing a page. IOW these things should be part of the url proper, not fragments.

Ok, so the hue and cry is specifically about the use of the technique when the content seeks to be indexed (and therefore includes the bang)? The author would not find a problem with GMail, for example, using a bookmark-able fragment like "#inbox/13038eb4c2b587f7" in the same manner as Gawker (that is: not referencing an anchor but describing an addressable page full of content)?

The problem is with any site that uses stuff after the hash to distinguish between what should be different application states. From the REST perspective, these applications just have one huge state and thus miss out on many of the benefits of REST.

What's worse, fixing this flaw necessitates breaking all of the application's URLs.

When pushState is used properly, a single-page app essentially becomes a transparent client-side proxy/cache, which maps much better onto REST.

Sorry but REST is fine with forcing the client to maintain its own state (in fact it's pretty much assumed the client will, for any non-trivial application). Using hashes in this manner shouldn't require the server to maintain additional state. If I'm missing something here, could you please elaborate?

Well, an application has many kinds of state on many different levels. The sort of state that serves as the S in REST is the one that a client changes by requesting and manipulating representations of resources identified by URIs.

An application composed of a single representation that implements the entire app with code-on-demand is not exploiting the REST architecture very much.

Actually, even if the application is properly broken up into URIs, it's still not entirely RESTful because the "engine of application state" has become Javascript + secret protocol rather than hypermedia.

Ah okay I see now, code-on-demand as a primary method does run contrary to REST. Thanks for clarifying.

I'm quite puzzled there too.

In what sense is using a hash as part of the address a hashbang?

Hashbang refrers to #!, #!, and only #!.

Google published a specification [1] for "Making AJAX Applications Crawlable" which uses #!. This has been widely adopted; it's plausible that the majority of web apps that store their state in fragment identifiers use this convention. That is why people are using the term "hashbang" to refer to the practice in general.

http://code.google.com/web/ajaxcrawling/docs/specification.h...

Once of the reasons Gawker moved away from hashbangs is that they weren't well supported by Google, despite this being a "Google specification". Nick Denton, the founder of Gawker, has some interesting tweets about the use of hashbangs over the past few months:

Nick Denton: "Dip in uniques largely because of drop in Google refers. Pageviews (which are driven more by core audience) less affected." -- http://twitter.com/nicknotned/status/61152134929981440

Nick Denton: "Google does not fully support "hashbang" URLs. So we're eliminating them rather than waiting for Mountain View." -- http://twitter.com/nicknotned/status/61465859079671808

Nick Denton: "Yeah, I'd advise against hashbang urls. Will kill search traffic -- even if you abide by Google protocol." -- http://twitter.com/nicknotned/status/62595141927583745

So here's a high-profile failure of hashbangs when it comes to being indexed by Google. Which means if it's search indexability you want, hashbangs isn't it. The Google spec just isn't mature enough, or well supported by Google search itself.

I think this article has a good explanation of what people find distasteful specifically about those hashbang fragments: http://news.ycombinator.com/item?id=2592741

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