- From: Jens Alfke <snej@google.com>
- Date: Wed, 26 Aug 2009 16:51:42 -0700
On Aug 26, 2009, at 4:01 PM, Linus Upson wrote: > The analogy was made comparing a user agent that purges local > storage to an OS throwing out files without explicit user action. > This is misleading since most files arrive on your computer's disk > via explicit user action. You copy files to your disk by downloading > them from the internet, copying from a network drive, from a floppy, > your camera, etc. A web app would also be pretty likely to put stuff in local storage as a result of explicit user action. The use cases seem pretty similar. Also, you're not counting files that you create locally. After all, files have to come from somewhere :) Those are the most precious since they're yours and they may not live anywhere else if you haven't backed them up or copied them elsewhere. There's no reason web-apps can't create the same kind of content, and it would look very similar to a user: I go to the word processor [website], click New Document, type some stuff, and click Save. Even if the save process involves migrating the local data up to the cloud, that transition is not instantaneous: it can take arbitrarily large amounts of time if there are network/server problems or the user is offline. During that time, the local storage represents the only copy of the data. There is therefore a serious race condition where, if the browser decides to purge local data before the app has uploaded it, the data is gone forever. > A better analogy would be, "What if watching TV caused 0-5MB size > files to silently be created from time to time in a hidden folder on > your computer, and when your disk filled up both your TV and > computer stopped working?" This is a cache ? that isn't the kind of usage I'm concerned about. Maybe the local storage API needs a way to distinguish between cached data that can be silently thrown away, and important data that can't. (For example, the Mac OS has separate 'Caches' and 'Application Support' subfolders of ~/Library/.) First, this is what quotas are for. The TV web-app would have a limited quota of space to cache stuff. Second, the browser should definitely help you delete stuff like this if disk space does get low; I'm just saying it shouldn't delete it silently or as part of some misleading command like "Empty Cache" or "Delete Cookies". > At a minimum the HTML 5 spec should be silent on how user agents > implement local storage policies. I would prefer the spec to make it > clear that local storage is a cache, domains can use up to 5MB of > space without interrupting the user, and that UAs were free to > implement varying cache eviction algorithms. That will have the effect of making an interesting category of new applications fail, with user data loss, on some browsers. That sounds like a really bad idea to me. To repeat what I said up above: Maybe the local storage API needs a way to distinguish between cached data that can be silently thrown away, and important data that can't. ?Jens -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.whatwg.org/pipermail/whatwg-whatwg.org/attachments/20090826/d93ae00e/attachment.htm>
Received on Wednesday, 26 August 2009 16:51:42 UTC