Re: Widgets on low memory devices

Grassel,

I currently have the system implemented as a single html file per packed
widget with a DIV for each view. There are two "magic" DIV IDs, one for
minimized and one for maximized and ideally I'd like to have 10 widgets
available for a user on their "widget desktop".

In my browser, and I *think* most browsers, when the widget html is loaded
the complete DOM is in memory including all scripts even if the visual
representation is not. Note that my platform is featurephone (>1MB memory)
not smartphone.

Essentially I'd like to support two kinds of widget:

a) Widgets which can show dynamic information when minimized, e.g. a
newsreader widget which displays a count of new articles, or for a weather
widget just a summary for today. The widget then shows more detail when
maximized, e.g. the complete article or the week's forecast.

b) Widgets which has a just an icon when minimized, but a resource-intensive
maximized view - for example a PacMan game widget.

..as you can imagine, the issue is that the complicated maximized views and
their scripts are in-memory even when not displayed.

The idea of just using an icon (rather than XHTML) for the minimized view is
not great for my implementation, as it makes the Weather Widget, or
Newsreader Widget difficult.

The concept of saving state (setPreferenceForKey) to share info between
different views is good - but it's the whole transition between the views
that I think falls between the gaps in the current spec.

Does this change your thinking at all?

Thanks,

Alex.


On 25/06/07, Grassel Guido (Nokia-NRC/Helsinki) <guido.grassel@nokia.com>
wrote:
>
>
> Dear Alex,
>
> Thanks for the input.
>
> How does a minimized view help to conserve memory (add more resources:
> CPU, bandwidth, and battery) compared to a maximized (normal) view?
> - From my own experience, the majority of system resources goes on keeping
> yet another Widget running in the browser engine,  the size of its visual
> representation makes only a comparably small difference. A well written
> Widget should put itself to idle state whenever it detects that it does not
> have the user's attention.
>
> - Experiments with multi-document support on the S60 browser tells that
> many today's smart phones have resources for 2-3 open document. Devices with
> over average amount of RAM can handle more. No more than one document should
> perform intensive JavaScript / DOM stuff at the same time. This gives some
> idea on how many Widgets can be running at the same time.
> - The Widget 1.0 spec defines an icon to be supplied with each Widget
> package that should be shown when the Widget is not running.
> Are several index.html files needed for a widget to have multiple views ?
> - I think it is not necessary. It can be worked quit well with some
> branching in just one file.
>
>
> Regards
> - Guido
>
> On 6/22/07 12:20 PM, "ext Alex Linde" <alex@joemoby.com> wrote:
>
> Hi,
>
> I've been reviewing the widget requirements with regard to implementation
> on low memory devices. Within our proposed implementation we would like to
> have widgets with one or more views - essentially a minimized view for the
> "widget dashboard" with an option for a widget to maximize to full screen.
>
> This is possible within the framework you have proposed, however for a
> single "index.html" it still requires that all views are loaded by the
> browser or widget engine.
>
> My question is whether the ideal implementation of multiple views should
> be:
>
> - Separate html files within the widget - essentially requiring that each
> view can save state to pass to the other.
> - Individual div sections in the index.html with style.display = "none"
> for views that should be removed from memory.
> - ..something else?
>
> Would it be possible for the group to suggest a recommended method of
> supporting multiple views and include this in their documentation? This
> would help both widget runtime developers and widget authors.
>
> Many thanks,
>
> Alex.
>
>
>
> Kind Regards
> - Guido
>
> -----
> Guido Grassel, Nokia Research Center, guido.grassel@nokia.com
>



-- 
Alex Linde
+44 7966 204 616