Thursday, February 15th, 2007

More on Offline Support in Firefox

Category: Firefox, Offline

Mozilla’s Rob O’Callahan blogged about the technologies behind yesterday’s posting on Zimbra’s off-line mode:

As Chris mentioned, there are four pieces to our offline puzzle… the only really new part is using &lquot;link rel=”offline-resource”&rquot; to put resources in a persistent “offline cache” that won’t accidentally evict your application. That is quite simple and once we’re confident we have the right semantics for it, we’ll definitely try to get it standardized somewhere.

One API that we are thinking about adding is support for script-controlled loading of resources into the offline cache. This needs to be designed in conjunction with a policy for deleting resources from the offline cache, something we haven’t settled on yet.

It’s a great update on the Mozilla team’s direction for off-line in future versions of Firefox.

Posted by Ben Galbraith at 7:00 am

3.3 rating from 13 votes


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this is an awesome idea. i wonder how soon before MS takes this one too.

Comment by ty — February 15, 2007

I don’t get the idea. Why don’t they do that by a HTTP header and by the same meta tag? Why should the application link itself, why doesn’t it just describes it in their page header? How will the application be able to invalidate this data, and how it will be able to add data? I think it’s not the idea we need.

Anyway, there is a protocol for data caching, we just need to extend that, if that’s necessary, but not creating new possibilities for the same thing. Maybe I don’t get the idea about it, don’t know.

I think the user should be warned about, that the application would like to store local data. The application should tell to the client, that it would need 100MB storage, and the user should say OK for it. Then the application from the current domain will be able to store as much data as it would like to do in this frame, with using a protocol.

Comment by András Bártházi — February 15, 2007

András, a web app without offline capability has no code that implements the server side functionality to link to (“link to itself”, in your words), such that the code can be downloaded and cached persistently in the browser. Web apps use PHP, Java, Ruby, etc. to implement their business logic and presentational layers. To become offline-enabled, a web app needs some extra JavaScript and other client-side content, which must be cached in a reliable way, not subject to eviction from the HTTP cache browsers use for page re-load speedup.

So this extra client-targeted offline-supporting content is what the link rel=”offline-cache” tags will reference. Hope this is clear now.


Comment by Brendan Eich — February 16, 2007

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