[Sugar-devel] sugar-web - API for storing data

[Daniel Narvaez]

Great stuff!

I'm a bit undecided about the API... I'll try to let it go through my head
a bit more, until you post a pull request :)


On 3 September 2013 16:52, Manuel Quiñones <manuq at laptop.org> wrote:

> I'm back into this.  After discussing with Daniel some weeks ago, we
> agreed that the activity is the one who knows if it needs to store,
> not the toolkit.  So we prefer to let the activity developer do the
> storing, instead of doing when the activity goes to the background.
>
> Also the API I have proposed at that time was only for text data.
> Storing in web activities is a bit more complicated because there is
> no file descriptor to write to.  On the other hand, most webapps store
> text in JSON format
>
> So now I'm proposing a helper class called JSONStore that uses the
> standard localSorage.  I made it work in Get Things Done activity.  I
> will send a PR to add it to sugar-web.  Here it is:
>
> https://github.com/manuq/gtd-activity/blob/master/js/jsonstore.js
>
> An adventage of using localStorage is that it persists in a normal
> browser as well.  See http://manuq.github.io/gtd-activity/
>
> The usage is like this:
>
> myStore = jsonstore.JSONStore();
>
> myReadyCallback = function () {};
> window.addEventListener('storeReady', myReadyCallback);
>
> var value = myStore.read('key'); // read
> myStore.write('key', newValue); // write
>
> // Or use localStorage directly, and then call save():
>
> var value = localStorage['key'];
> localStorage['key'] = newValue;
> myStore.save();
>
>
> 2013/8/16 Daniel Narvaez <dwnarvaez at gmail.com>:
> > Hey,
> >
> > It seems be have two (mostly) independent questions here
> >
> > - How do we notify an activity of certain global events, being them
> > onPause/onStop or onRead/onWrite.
> >
> > If we want them to be passed in activity.setup() I think we should use an
> > object, like {"onSomething": ..., "onSomethingElse":..}. That will allow
> to
> > subscribe only to some of the available events. With two events that
> would
> > probably be overkill but if nothing else I think onStart/onPause/onStop
> > should be supported, even if we also have onRead and onWrite. They are
> > needed for more than writing to the datastore.
> >
> > Though, any reason to not use custom DOM events? This seems exactly the
> use
> > case they are designed for.
> > http://www.w3.org/TR/DOM-Level-3-Events/#extending_events-Custom_Events
> >
> > - Should we have onRead and onWrite events.
> >
> > What you are proposing is a bit different from what you have
> implemented. In
> > your patch onWrite does only a couple of things
> >
> > 1 Proxy both onPause and onStop to the same write method.
> > 2 Close the activity in onStop.
> >
> > I think 1 is not enough to justify onWrite existence, it's easy enough
> for
> > the concrete activity to do it if wanted.
> > About 2, I think the concrete activity needs more control on when it is
> shut
> > down. It might want to do so after having written some file outside the
> > journal, for example.
> >
> > Now, you are proposing that we pass metadata in both read and write,
> > similarly to the gtk API. But what about the data? I don't see exactly
> where
> > you are going with this, so it would helpful if you could sketch out that
> > API.
> >
> >
> > That was a bit long, to summarize:
> >
> > * I think onStart/onPause/onStop should be there in any case.
> > * On the top of those, your current onWrite implementation adds too
> little
> > to be justified.
> > * I tend to think we should use custom DOM events here instead of
> callbacks,
> > if possible.
> >
> > On 16 August 2013 14:01, Manuel Quiñones <manuq at laptop.org> wrote:
> >>
> >> This is one of the most important APIs we will have, so I would
> >> like to open discussion on it.
> >>
> >> In GTK activities, the activity developer subclass Activity, and
> >> override read() and write() methods.
> >>
> >> In web activities, we don't have that kind of hierarchy.  Instead, the
> >> activity developer imports 'activity/activity' module, and calls
> >> activity.setup() .  Then she/he can use activity.getDatastoreObject()
> >> to read and write.
> >>
> >> In GTK activities, 'read' is called at startup and 'write' is called
> >> when the activity goes to the background or when it stops.  Recently,
> >> I added in sugar-web those notifications, with the intention to make
> >> web activities behave like GTK ones.
> >>
> >> I provided an initial patch and dnarvaez proposed another option:
> >> https://github.com/sugarlabs/sugar-web/pull/74
> >>
> >> So we can:
> >>
> >> - Let web developers connect to the 'pause' and 'stop' notifications,
> >>   and use the activity datastore object directly. Pro: is more
> >>   flexible.  Con: more work in the activity side: error handling,
> >>   datastore object handling.
> >>
> >> - Subscribe 'read' and 'write' functions in activity.setup() .  They
> >>   will be called as expected, like in GTK.  'read' will have a JSON
> >>   string as argument.  'write' must return a JSON string.  Pro:
> >>   simpler approach.  Con: less flexibility in the activity side.  A
> >>   mockup can be found in this comment:
> >>
> >>
> https://github.com/manuq/sugar-web/commit/3c2420f59c9aa8df44d2c0d639fe37b4af63f9fb#commitcomment-3872770
> >>
> >> Thoughts?  Any other ideas?
> >>
> >>
> >> --
> >> .. manuq ..
> >>
> >> _______________________________________________
> >> Sugar-devel mailing list
> >> Sugar-devel at lists.sugarlabs.org
> >> http://lists.sugarlabs.org/listinfo/sugar-devel
> >
> >
> >
> >
> > --
> > Daniel Narvaez
>
>
>
> --
> .. manuq ..
>



-- 
Daniel Narvaez
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sugarlabs.org/archive/sugar-devel/attachments/20130905/2f8cc029/attachment-0001.html>