- From: Michael Nordman <michaeln@google.com>
- Date: Tue, 20 Apr 2010 15:31:02 -0700
- To: Nikunj Mehta <nikunj@o-micron.com>
- Cc: public-webapps@w3.org, Joćo Eiras <joaoe@opera.com>, Mark Seaborn <mseaborn@chromium.org>
- Message-ID: <p2tfa2eab051004201531k8f63cffbk5d1095723435b835@mail.gmail.com>
On Tue, Apr 20, 2010 at 3:10 PM, Nikunj Mehta <nikunj@o-micron.com> wrote: > As I see it, there's no such thing as "permanent" storage for Web browser > managed data. Even if a site expresses preferences that it would like to > keep its data resident for a long time, there cannot be a "guarantee" for > the data to be there permanently. If applications are bound to have to deal > with data disappearing while they are not running, we should not need to > spec browser behavior around the notion of purgeable or permanent. > I see a difference between a cached version of a picture you've downloaded vs a new picture taken while on vacation by a camera built into the device and placed into a local repository managed by the user-agent. There is only one copy of that picture in the world. I'm looking for ways to make these storage APIs widely available w/o a lot of user-prompting, but also for ways for webapps to express stronger guarantees when needed. I think the notion of purgeable vs permanent may help reconcile these conflicting goals. > It makes sense for an application, OTOH, to say that it does not need data > to be stored on disk. IOW, create a database that is non-durable and, hence, > kept only in memory. Such databases are required to be empty upon creation. > They may be spilled over to disk, if implementations like to, but they will > not be retained from session to session. > > Nikunj > > > On Apr 20, 2010, at 2:37 PM, Michael Nordman wrote: > > I'd like to back up and challenge the notion of a per-site quota. > > In this discussion and others there is an underlying assumption that each > site has some well defined limit that the user-agent has granted it. I doubt > that's the best model. (Fyi: the chrome team's overly simplistic model > whereby each site gets 5M was not chosen because its a good model, this was > done just to proceed with building out the storage APIs independent of a > real storage management strategy). > > I'd like to set aside the per-site quota assumption and explore some > alternative models for web storage management. > > Some thoughts about the world we're designing for. There are an open ended > number of sites, each of which *could* use web storage in some form. From > that fact alone, it's impossible to come up with a quota that could be > granted to each and every site. It seems likely that the number of sites > that will actually require "permanent" storage is small compared to the > number of sites that *could* make use of more "volatile" storage, to borrow > jorlow's term, where the volatile data on disk can get scrapped by the > user-agent as needed. Maybe a better term for that class of storage is > "purgeable"? > > Maybe we should be designing for what seems to be the more common case, > lots of sites that make use of volatile/purgeable storage. But also come up > a means whereby the smaller number of sites that require stronger guarantees > can express the need for more permanent storage. > > "What if" by default all local storage is "purgeable". A lot of quota > issues melt away in this case since the user agent is free to reclaim > anything at anytime. I think it'd be reasonable if the user-agent never > asked the user anything on a per-site basis. A user-agent could warn when > system disk space crossed thresholds and give the user an option to set > limits on system disk space usage for webstorage as a whole. > > "What if" when creating local storage repositories (WebDBs or IndexedDBs or > WebFileSystems or AppCaches) there was an optional means for the webapp to > express "please consider this a permanent storage repository". The first > time a site request "permanent" storage could be a reasonable time to > interact with the user in some form, or to consult the user prefs about > allowing permanent storage w/o being asked. > > I think ericu is baking in a distinction in between 'permanent' and > 'temporary' in the FileSystem API he's working on. Some harmony across all > flavors of local storage could be good. > > I actually think local storage management is an area where the webplatform > has a chance to do a much better job then the desktop platforms have > historically done. We don't need no stinking quotas ;) But we also don't > need untold amounts of unused permanent storage littering disk drives > needlessly around the globe (until the user gets a new system). A silly > analogy. A computer is like a ship at sea. After years of usage, a whole > bunch of barnacles build up on the hull and slow the vessel down. The > webplatform to date is barnacle free in this area because there are no > permanent local storage facilities... lets try to make these new features > not so barnacle prone too. > > Cheers > -Michael > > On Tue, Apr 20, 2010 at 11:17 AM, Shawn Wilsher <sdwilsh@mozilla.com>wrote: > >> On 4/20/2010 4:11 AM, Mark Seaborn wrote: >> >>> 1) It doesn't allow a web app to ask for a storage allocation up front, >>> before it starts to consume the storage. >>> >> Why does that matter? >> >> >> 2) In Opera, the quota can only be increased in multiples of about 15, so >>> it >>> takes three prompts to get up into the range of gigabytes. >>> >> But there is an unlimited option, yeah? >> >> >> 3) The web app can't choose when the question is put to the user. >>> 4) The web app doesn't know how much storage has been allocated, so it >>> doesn't know when a question will be asked. >>> 5) In Opera, if the user chooses "Reject", they don't get prompted again. >>> This means that asking the user at an appropriate time is important for >>> the >>> continued functioning of the web app. Prompting the user at the wrong >>> time >>> will interrupt them with a page-modal dialog which they might want to get >>> rid of with "Reject", which would potentially break the web app by >>> leaving >>> it unable to get more storage. >>> >> These all feel like user-agent specific worries on how the user agent >> wants to bring this to the attention of the user. >> >> Cheers, >> >> Shawn >> >> > >
Received on Tuesday, 20 April 2010 22:31:34 UTC