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RE: [widgets] What does it mean to have an unavailable API

From: Marcin Hanclik <Marcin.Hanclik@access-company.com>
Date: Tue, 2 Jun 2009 16:28:46 +0200
To: Scott Wilson <scott.bradley.wilson@gmail.com>, Henri Sivonen <hsivonen@iki.fi>
CC: public-webapps <public-webapps@w3.org>
Message-ID: <FAA1D89C5BAF1142A74AF116630A9F2C0A26ED9041@OBEEX01.obe.access-company.com>
Hi Scott,

In BONDI we have discussed the (has/request)Feature() for some time.
http://bondi.omtp.org/1.0/security/BONDI_Architecture_and_Security_v1.0.pdf, section 4.3

A few points for further discussion:
1. feature (at least in BONDI) is an abstract thing, not just one function. So hasFeature() is simply optimized checking procedure. If you check for a feature and discover that it is available, you may/should/must assume that a set of functions is available. Otherwise, you have to check each function individually and basically you cannot assume that if one functions is available, then the other is as well.

2. requestFeature() adds dynamism to the Website content. Widgets express their dependency statically by <feature>.
http://bondi.omtp.org/1.0/security/BONDI_Architecture_and_Security_Appendices_v1.0.pdf B.2 specifies more details.

Thanks.

Kind regards,
Marcin

Marcin Hanclik
ACCESS Systems Germany GmbH
Tel: +49-208-8290-6452  |  Fax: +49-208-8290-6465
Mobile: +49-163-8290-646
E-Mail: marcin.hanclik@access-company.com

-----Original Message-----
From: public-webapps-request@w3.org [mailto:public-webapps-request@w3.org] On Behalf Of Scott Wilson
Sent: Tuesday, June 02, 2009 3:18 PM
To: Henri Sivonen
Cc: public-webapps
Subject: Re: [widgets] What does it mean to have an unavailable API

I think in such a case the UA should not be expected to make frob()
available, and the Widget should not expect frob() to be present.

For example, in the Shindig opensocial runtime, client JS is injected
based on the <require> elements of the gadget. If it isn't declared,
it isn't injected, and if you try calling those functions they just
aren't there.

What this does make less clear for me is in W:A&E why you'd ever want
to call "hasFeature()"?

S


On 2 Jun 2009, at 13:51, Henri Sivonen wrote:

>>
>> Ok. I see what you mean. Widget.hasFeature has slightly different
>> semantics (in widgets, it means "did that feature I requested load
>> and become available?"
>
> Which brings up the issue that it's unclear what it means for an API
> to have latent support but not having been activated with <feature>.
>
> If a widget UA has an implementation for window.frob() and frob()
> requires <feature> activation, what should happen when frob() hasn't
> been activated with <feature>? Should there be no function object
> for frob()? Or should it be there but throw upon calling? Or
> something else.
>
> Please specify this.
>
> --
> Henri Sivonen
> hsivonen@iki.fi
> http://hsivonen.iki.fi/
>
>
>


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Received on Tuesday, 2 June 2009 14:29:43 GMT

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