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Subject: [emergency] Re: Attributes vs Elements


Oh Boy! Lemme find a match.

Sorry, couldn't help myself there for a second. I'm better now. Whew!

I usually duck this one, and just use elements as much as I can.
However,  I plan to stay out of this debate, so don't take that as a
recommendation.

Ciao,
Rex

At 2:09 PM -0400 5/8/03, R. Allen Wyke wrote:
>Oh boy - you have just stepped into one of the biggest debates of all
>times. However, you are right - it is appropriate for us to discuss this
>and to do so within the larger audience of the EM TC. I will take what
>you have, and run with it (fully realizing that I am sure it will
>stimulate some responses :)
>
>The objective of this discussion will be to formalize some *basic*
>guidelines we should all adhere to for any XML schemas we develop. I
>think it is best we do not set hard and fast rules and that we provide
>some wiggle room for each SC, but we do need to be consistent in at
>least some fashion. I will include the outcome in the guidelines
>document I am working on.
>
>For the context of this debate and to start the discussion, let me list
>the basis of how I came to a recommendation:
>
>1. There is no single and always correct answer.
>
>2. You will be hard pressed to find a definitive human definition of
>"element" or "attribute", in the context of XML, to provide a single
>answer to this question. However, it is generally accepted that
>attributes are metadata about its containing element with some implied
>inheritance in any subsequent child elements.
>
>3. The 6th design goal of the original XML Recommendation
>http://www.w3.org/TR/REC-xml#sec-origin-goals) states that "XML
>documents should be human-legible and reasonably clear."
>
>4. There is a technical argument within XML Schema Part 2: Datatypes
>(around internationalization), to keep human-readable text out of
>attribute values. Under the xsd:string datatype
>(http://www.w3.org/TR/xmlschema-2#string), it says:
>
>NOTE:  Many human languages have writing systems that require child
>elements for control of aspects such as bidirectional formating or ruby
>annotation (see [Ruby] and Section 8.2.4 Overriding the bidirectional
>algorithm: the BDO element of [HTML 4.01]). Thus, string, as a simple
>type that can contain only characters but not child elements, is often
>not suitable for representing text. In such situations, a complex type
>that allows mixed content should be considered. For more information,
>see Section 5.5 Any Element, Any Attribute of [XML Schema Language: Part
>2 Primer].
>
>In not so many words, it says don't use attributes for human-readable
>text. You are not able to include elements, for further description, in
>attribute values and things like hard returns are problematic from a
>programming standpoint (not too mention a long attribute value violates
>#3 above).
>
>5. From a programming standpoint, accessing elements vs. attributes
>isn't very different if you use a good parser/processor.
>
>Based on these, I recommend we do the following as part of our
>guidelines.
>
>--------------------------
>Any and all schema developed by the EM TC and its SCs SHOULD:
>
>1. in general practice separate metadata into attributes.
>
>2. make every effort to keep documents human-legible and reasonably
>clear as specified in the Origin and Goals
>(http://www.w3.org/TR/REC-xml#sec-origin-goals) of the "Extensible
>Markup Language (XML) 1.0 (Second Edition)".
>--------------------------
>
>Ok, the gasoline has been poured. I am sure someone will now strike the
>match :)
>
>Allen
>
>On Wed, 2003-05-07 at 18:32, Weltman, Jerry wrote:
>>  Allen and Rick,
>>
>>  During the Notifications and Messaging SC a couple of weeks ago, I
>>  brought up the issue that we could be using attributes for some of the
>>  data instead of elements. The response was overwhelming that we should
>>  not be using attributes, which is fine by me. But I am wondering
>>  whether there should be some debate among the TC in general on this
>  > issue since it seems like we would prefer that all of the TC's XML
>>  structures have a similar style.
>>
>>  Or perhaps I am missing something. Is there something about the work
>>  we are doing that makes attribute-free XML structures an obvious
>>  common goal?
>
>>  Jerry
>--
>R. Allen Wyke
>Chair, Emergency Management TC
>emtc@nc.rr.com
>http://www.oasis-open.org/committees/emergency


--
Rex Brooks
GeoAddress: 1361-A Addison, Berkeley, CA, 94702 USA, Earth
W3Address: http://www.starbourne.com
Email: rexb@starbourne.com
Tel: 510-849-2309
Fax: By Request


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