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Re: question about number of occurrences of author and content elements (in Widget packaging spec)

From: Marcos Caceres <marcosc@opera.com>
Date: Fri, 02 Jul 2010 12:00:22 +0200
Message-ID: <4C2DB8B6.3060101@opera.com>
To: Ricardo Varela <phobeo@gmail.com>
CC: public-device-apis@w3.org, public-webapps <public-webapps@w3.org>
Hi Ricardo,

(moving discussion to public-webapps)

On 7/2/10 5:56 AM, Ricardo Varela wrote:
> hallo all, hallo Marcos,
>
> We have a small question regarding what we interpret may be an
> inconsistency in the behaviours for parsing a config file as commented
> in the W3C widget packaging spec [1]
>
> According to the spec (latest and also older versions), the
> occurrences of some elements (eg: author or content) have to be zero
> or one

I'm sorry, the specification is unclear. It says "expected children (in 
any order)", but it certainly is not intended to be a restriction on 
authors - that is to say, it would make no sense to punish authors who 
put in two author elements by mistake. A conformance checker could then 
warn if something out of the expected (such as two author elements) if 
found in the document. This is defined in this yet to be published spec:

http://dev.w3.org/2006/waf/widgets-pc-cc/Overview.src.html

> However, on the algorithm to process a configuration document quoted
> below, it states: "If this is not the first author element
> encountered, then the user agent must ignore this element and any
> child nodes" It just says ignore and doesn't say to consider it as
> error
>
> Isn't this a contradiction in the parsing of the configuration
> document? We understand that it should be one of these 2 cases:
>
> a) we allow for more than one instance of author and content and let
> the first one take precedence (and therefore the occurrences should be
> "zero or more")

No, only one is expected.

> b) we allow only one instance of author and content elements (and
> therefore the parsing algorithm has got to stop with error on further
> occurrences)

Certainly not: the parser is not a conformance checker. The parser 
should be able to flexibly handle all garbage input gracefully, as well 
as be future compatible (in case we want to allow more than one author 
or content element on the future).

> Would appreciate some clarification about this, as we want to clarify
> what to do for our compliance tests

I hope that clarifies things. If not, I'm happy to discuss further.

Also, are you making your own compliance tests or using the official ones?:

http://dev.w3.org/2006/waf/widgets/test-suite/

> Thanks a lot in advance!
>
> Saludos!
>
> [1] http://www.w3.org/TR/widgets/
>

-- 
Marcos Caceres
Opera Software
Received on Friday, 2 July 2010 10:01:00 GMT

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