xml-dev - Re: [SML] Whether to support Attribute or not?

[Joe Lapp <jlapp@webmethods.com>]

Yes, mixed content is an issue, which is why I started the "Data Markup Language" thread.  You might cast your vote there.

At 05:28 PM 11/28/1999 -0800, Paul Tchistopolskii wrote:
>
>> I understand the problem better after reading other people's responses.
>> What threw me was the analogy to object data and behavior, which I don't
>> think is the right analogy.
>> 
>> In each of these example elements
>> 
>>   <lineitem><model>XYZ</model><quantity>3</quantity></lineitem>
>>   <lineitem quantity="3"><model>XYZ</model></lineitem>
>>   <lineitem quantity="3">XYZ</lineitem>
>> 
>> 'lineitem' has two properties: model and quantity.  It happens that in the
>> last example the model is not labelled 'model'.  The label is missing,
>> since strictly speaking XYZ is not the lineitem.
>> 
>> If we throw away the quantity attribute we are left with...
>> 
>>   <lineitem>XYZ</lineitem>
>> 
>> XYZ may indeed represent the line item, but we could have chosen a more
>> specific word...
>> 
>>   <model>XYZ</model>
>> 
>> I'd argue that if an element has attributes in addition to text content,
>> then the attributes together with the content define the element, and the
>> content must therefore be yet one more property of the element.  The
>> property simply has not been named.
>
>.... I think, <PCDATA> could be a name of such a  'hidden property' property ? ;-)
> 
>> You might consider that a shortcoming of XML.  
>
>I don't understand where is a shortcoming here .... I think nobody knows 
>for sure what will happen with some 'plain' PCDATA field in the future - it 
>may easily become mixed content, so considering PCDATA to be 
>a special case of mixed content looks reasonable and consistent to me.
>
>But I agree, when you have PCDATA but  *not*  mixed content it usualy 
>means that you'l better to specify some new element / attribute ... 
>Do I understand your point ? 
>
>I don't  understand  what to do with such a knowledge ... 
>
>> By allowing attributes it allows elements to have unnamed properties.  
>> I'm having trouble interpreting this as an advantage that attributes give.  
>
>> Were there never attributes, every property would have a label.  
>
>> (Unless there is mixed content, which prompts my next thread...)
> 
>> I think the solution for SML/XML conversion is give this property an
>> explicit name.
>
>What is the *problem* you want to solve ?
>
><lineitem><quantity>3</quantity>XYZ</lineitem> is valid XML and 
>valid SML as well.  
>
>Or I'm missing something in SML ?
>
>Or you are saying PCDATA should be restricted from SML, and 
>only mixed content should remain?
>
>What is the purpose ? ... Actualy, maybe there is some .... 
> 
>I don't want to drop mixed content from SML. It will 
>kill the markup abilities and I don't see any reasons why 
>it should be killed.  Maybe I'm missing something here.
>
>Rgds.Paul.
> 
--
Joe Lapp              (Looking for some good people to help design
Senior Engineer        and build the Internet's business-to-business
webMethods, Inc.       XML infrastructure.  We are 100% Java.)
jlapp@webMethods.com           http://www.webMethods.com

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