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From Brian LeRoux...@brian.io>
Subject Re: Configuring the File plugin
Date Tue, 14 Jan 2014 18:44:11 GMT
So, to be clear and terse: what are the use cases / why are we adding more
config?


On Tue, Jan 14, 2014 at 10:34 AM, Ian Clelland <iclelland@chromium.org>wrote:

> On Tue, Jan 14, 2014 at 10:52 AM, Andrew Grieve <agrieve@chromium.org
> >wrote:
>
> > On Tue, Jan 14, 2014 at 10:38 AM, Ian Clelland <iclelland@chromium.org>
> > wrote:
> > > On Mon, Jan 13, 2014 at 9:16 PM, Andrew Grieve <agrieve@chromium.org>
> > wrote:
> > >
> > >> I think we need two things for transitioning to different PERSISTENT /
> > >> TEMPORARY locations:
> > >> 1. The ability for the user to retrieve the files at the old location
> > >> (so they can be moved to the new location)
> > >> 2. The ability to turn turn on the change with a switch (e.g.
> > >> <preference name="IosUseLegacyFileSystemPath" value="true" />)
> > >>
> > >> I'd love for the default to be the new locations so that new apps
> > >> don't forget to turn on the preference and find out they need to
> > >> migrate later on.
> > >>
> > >
> > > This is the really dangerous bit, though. If we make the default
> anything
> > > but the current behaviour, then devs *will* update their plugins and
> > push,
> > > and users *will* lose the ability to access old saved files. We will
> > > absolutely encounter the situation where developers test their app with
> > > blank filesystems, and everything works fine, but data is rendered
> > > inaccessible to users who upgrade from an old version. And I'm sure
> it'll
> > > happen no matter how loudly we announce the change.
> > >
> > > I would sooner make the new plugin be "broken by default", so that the
> > app
> > > doesn't even start until you add a configuration preference, one way or
> > the
> > > other. Then we could recommend at that time, "if you have an existing
> app
> > > with users, then use the old value; if this is a brand new app, use the
> > new
> > > one".
> >
> > I really like this idea!
> >
> > >
> > > Also - the simpler our instructions can be, the better. I don't think
> > >> most devs even realize that they are doing a foolish thing with the
> > >> way things are set up right now, so telling them to configure their
> > >> own paths might put too much of a burden on them (they'd have to learn
> > >> where files should go, and then also figure out how our config syntax
> > >> works).
> > >>
> > >
> > > True. The simple case should be as simple as possible. Ideally, doing
> > > nothing at all should get them some reasonable behaviour, compatible
> with
> > > previous versions.
> > >
> > >
> > >>
> > >> The case of adding new FS roots is compelling, but I think most users
> > >> would appreciate FS roots for content, assets, sdcard, etc to be
> > >> pre-built-in rather than have to wire them up themselves.
> > >>
> > >
> > > Agreed. Those ones should be available out-of-the-box, either as part
> of
> > > File, or as part of a related plugin. (Leaning towards File, since it
> is
> > > already providing content and assets filesystem URLs)
> > >
> > >
> > >
> > >> One thing that jumped out to me is the src= argument:
> > >> <filesystem name="documents"
> > >>     type="local-filesystem"
> > >>     prefix="cdvfile://localhost/documents"
> > >>     src="Documents" />
> > >>
> > >> If the goal is for these to be customizable, then it's not that
> > >> flexible to use pre-defined values in the src= argument. Perhaps
> > >> instead of using config.xml, the File plugin could have a
> > >> registerFileSystemRoot(name, type, prefix, rootPath) function that
> > >> could be used for this purpose. That way plugins could compute their
> > >> root paths and then call this function at plugin init time.
> > >>
> > >
> > > That was mostly an off-the-top-of-my-head strawman for the format.
> > However,
> > > it does address the issue of how to specify "this filesystem lives at
> the
> > > NSTemporaryDirectory location; that one lives at NSLibraryDirectory",
> > > without having to know the real filesystem path for those things.
> > >
> > > I expected that the interpretation of something like a "src" attribute
> > > would be very dependent on the filesystem type, and specialized to that
> > > type, rather than representing an absolute device fs path.
> >
> > If the valid values here are pre-determined by the FS type, then I
> > don't know why we'd have this configuration.
> > Let's just expose all of the roots that the FS knows about. If we want
> > to be able to toggle some on/off, then let's add a pref for
> > "fs-type-whitelist" which is just a comma-separated-list.
> >
> >
>
> A comma-separated list isn't so bad; in fact, given the call signature of
> requestFileSystem, the *order* of items in that list may be the critical
> thing. A CSL is certainly easier to shoehorn into our existing config
> parsing than a whole block of XML, even if it's a bit uglier.
>
> What about something shaped like
>
> <preference name="filesystems" value="temporary,documents,assets,library"
> />
>
> Then you could switch "documents" and "library" in the list, and you would
> be storing files in the new position (by the definition of
> window.PERSISTENT).
>
> Ian
>
> > >
> > >
> > >>
> > >>
> > >>
> > >> Another thing that occurred to me (maybe off topic?): Why:
> > >> cdvfile://localhost/documents
> > >> instead of:
> > >> cdvfile://documents/
> > >> Looking at this URL-wise, I think it would be a nice-to-have to have
> > >> the type encoded as the hostname so that root-relative URLs would work
> > >> with the URLS.
> > >>
> > >
> > > We discussed this at the Waterloo meetup, and there was definitely some
> > > push for having the authority part in the URL be the real authority
> > > (localhost), for consistent URL handling.
> > >
> > > Having the FS type be the authority would make some of the internal URL
> > > parsing easier, but I don't know if it causes problems anywhere else.
> > >
> > >
> > >>
> > >>
> > >> Could we get away with just two parameters to each FS root?
> > >> 1. Name (use this to determine prefix as cdvfile://${name})
> > >> 2. src (URI to be considered the root of the FS).
> > >>
> > >
> > > Those are, internally, the parameters used by the "local filesystem" FS
> > > type (i.e., not "content" or "assets library".) The actual device-FS
> > root,
> > > though, is currently determined at run time by the device, based on
> > whether
> > > it is the temporary or persistent FS.
> > >
> > >
> > >>
> > >>
> > >>
> > >>
> > >> On Mon, Jan 13, 2014 at 4:29 PM, Ian Clelland <iclelland@chromium.org
> >
> > >> wrote:
> > >> > On Mon, Jan 13, 2014 at 3:21 PM, Jesse <purplecabbage@gmail.com>
> > wrote:
> > >> >
> > >> >> Will any of the following work?
> > >> >>
> > >> >> <img src="cdvfile://localhost/persistent/1.png"/>
> > >> >>
> > >> >> xhr.open("GET","cdvfile://localhost/persistent/data.txt");
> > >> >>
> > >> >> <link rel="stylesheet" type="text/css"
> > >> >> href="cdvfile://localhost/persistent/style.css"/>
> > >> >>
> > >> >
> > >> >
> > >> > If the new file plugin is installed, and the file exists, then the
> > first
> > >> > three of those should definitely work (assuming the default
> > >> configuration).
> > >> >
> > >> >
> > >> >>
> > >> >> <a href="cdvfile://localhost/temporary/site/temp.html"
> > >> >> target="_blank">Review Site</a>
> > >> >>
> > >> >
> > >> > I'm not sure about this -- haven't tried it. If it's doing
> navigation,
> > >> then
> > >> > I don't know how it plays with the fact that plugins get unloaded
or
> > >> reset
> > >> > at some point.
> > >> >
> > >> > The in-app-browser version of this:
> > >> >
> > >> > window.open("cdvfile://localhost/temporary/site/temp.html",
> "_blank")
> > >> >
> > >> > should work just fine.
> > >> >
> > >> >
> > >> >
> > >> >>
> > >> >>
> > >> >> @purplecabbage
> > >> >> risingj.com
> > >> >>
> > >> >>
> > >> >> On Mon, Jan 13, 2014 at 10:37 AM, Brian LeRoux <b@brian.io>
wrote:
> > >> >>
> > >> >> > I am apprehensive about making this surface configurable.
(I can
> > live
> > >> w/
> > >> >> > our own protocol cdvfile:// personally).
> > >> >> >
> > >> >> > The main use case is being able to add custom storage providers
> in
> > the
> > >> >> > future?
> > >> >> >
> > >> >> > (Might be good to add this to the 'lets talk configuration'
> > backlog /
> > >> >> > meeting.)
> > >> >> >
> > >> >> >
> > >> >> > On Mon, Jan 13, 2014 at 7:32 AM, Ian Clelland <
> > iclelland@chromium.org
> > >> >> > >wrote:
> > >> >> >
> > >> >> > > The new File plugin is essentially ready, for iOS and
Android
> > (with,
> > >> >> > > hopefully, no breaking changes for those or other platforms)
> > >> >> > >
> > >> >> > > I had to move away from the "filesystem://" URL scheme
-- on
> > Android
> > >> >> 4.4,
> > >> >> > > that scheme appears to be special, and doesn't defer
to
> > >> >> > > WebView.shouldInterceptRequest(). (I filed
> > >> >> > > https://code.google.com/p/chromium/issues/detail?id=333395
on
> > >> Friday
> > >> >> > once
> > >> >> > > I
> > >> >> > > had isolated the problem.) For now, I've settled on
> "cdvfile://",
> > >> but
> > >> >> the
> > >> >> > > issue is open to bikeshedding, I suppose.
> > >> >> > >
> > >> >> > > What I'd really like to open for discussion though,
is the idea
> > of
> > >> >> making
> > >> >> > > the whole plugin configuration, er, configurable.
> > >> >> > >
> > >> >> > > The URL scheme is one driving force behind this; the
historical
> > >> >> locations
> > >> >> > > of the TEMPORARY and PERSISTENT filesystems is another;
the new
> > >> ability
> > >> >> > to
> > >> >> > > open up completely new filesystems is a third.
> > >> >> > >
> > >> >> > > I'm thinking of implementing a section in config.xml
that would
> > >> define
> > >> >> > the
> > >> >> > > names of the installed filesystems available to a Cordova
app,
> > along
> > >> >> with
> > >> >> > > their type, the URL prefix to use, and any other required
> details
> > >> (like
> > >> >> > > *where the files live*). Something like this:
> > >> >> > >
> > >> >> > > <widget>
> > >> >> > >   <filesystems platform="android">
> > >> >> > >     <filesystem name="temporary" type="local-filesystem"
> > >> >> > > prefix="cdvfile://localhost/temporary" src="cache" />
> > >> >> > >     <filesystem name="persistent" type="local-filesystem"
> > >> >> > > prefix="cdvfile://localhost/persistent" src="Documents"
/>
> > >> >> > >     <filesystem name="content" type="content-filesystem"
> > >> >> > > prefix="content://" />
> > >> >> > >   </filesystems>
> > >> >> > > </widget>
> > >> >> > >
> > >> >> > > or
> > >> >> > >
> > >> >> > > <widget>
> > >> >> > >   <feature name="File">
> > >> >> > >     <filesystems platform="android">
> > >> >> > >       <filesystem name="temporary" type="local-filesystem"
> > >> >> > > prefix="cdvfile://localhost/temporary" src="cache" />
> > >> >> > >       <filesystem name="persistent" type="local-filesystem"
> > >> >> > > prefix="cdvfile://localhost/persistent" src="Documents"
/>
> > >> >> > >       <filesystem name="content" type="content-filesystem"
> > >> >> > > prefix="content://" />
> > >> >> > >     </filesystems>
> > >> >> > >   </feature>
> > >> >> > > </widget>
> > >> >> > >
> > >> >> > > (The platform's defaults.xml, or whatever we're calling
it
> these
> > >> days,
> > >> >> > > could specify the default mapping, so that devs could
write
> > >> >> > cross-platform
> > >> >> > > apps without having to add this for every platform,
or even at
> > all,
> > >> if
> > >> >> > they
> > >> >> > > don't care to change it)
> > >> >> > >
> > >> >> > > I think that being this explicit will let us change
the url
> > scheme
> > >> as
> > >> >> > > needed (hopefully cdvfile won't need to change, but
it would
> have
> > >> if it
> > >> >> > was
> > >> >> > > still "filesystem"). It could eventually allow new FS
plugins
> to
> > be
> > >> >> added
> > >> >> > > to an app with this mechanism. And it would mean that
we could
> > roll
> > >> >> out a
> > >> >> > > default configuration that left the iOS files in their
current
> > >> >> locations:
> > >> >> > >
> > >> >> > > <filesystem name="temporary"
> > >> >> > >     type="local-filesystem"
> > >> >> > >     prefix="cdvfile://localhost/temporary"
> > >> >> > >     src="Temporary" />
> > >> >> > > <filesystem name="persistent"
> > >> >> > >     type="local-filesystem"
> > >> >> > >     prefix="cdvfile://localhost/persistent"
> > >> >> > >     src="Documents" />
> > >> >> > >
> > >> >> > > and then, in a later version, we could change the default
for
> new
> > >> >> > projects
> > >> >> > > to
> > >> >> > >
> > >> >> > > <filesystem name="temporary"
> > >> >> > >     type="local-filesystem"
> > >> >> > >     prefix="cdvfile://localhost/temporary"
> > >> >> > >     src="Temporary" />
> > >> >> > > <filesystem name="persistent"
> > >> >> > >     type="local-filesystem"
> > >> >> > >     prefix="cdvfile://localhost/persistent"
> > >> >> > >     src="Library" />
> > >> >> > > <filesystem name="documents"
> > >> >> > >     type="local-filesystem"
> > >> >> > >     prefix="cdvfile://localhost/documents"
> > >> >> > >     src="Documents" />
> > >> >> > >
> > >> >> > > and existing projects shouldn't see any change. And
in the
> > meantime,
> > >> >> any
> > >> >> > > dev who wanted to use the more sensible filesystem locations
> > could
> > >> just
> > >> >> > > change their own config.xml.
> > >> >> > >
> > >> >> > > I'm going to take a stab at implementing this as described,
but
> > >> >> > discussion
> > >> >> > > is certainly welcome before it goes out to the world.
As
> multiple
> > >> >> people
> > >> >> > > have said, we need to get this right, and not hurt all
of our
> > >> existing
> > >> >> > > devs.
> > >> >> > >
> > >> >> > > Ian
> > >> >> > >
> > >> >> >
> > >> >>
> > >>
> >
>

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