[Nml-wg] XML syntax for NML relations

[Jason Zurawski]

Hi Freek/All;

On 8/16/11 7:36 AM, thus spake Roman Łapacz:
> W dniu 2011-08-16 12:09, Freek Dijkstra pisze:
>> Hi,
>
> Hi Freek,
>
>> I've been thinking about the relation syntax.
>>
>> So far, we have seen these two proposals:
>>
>>     <nml:link id="urn:ogf:network:example.net:link_A-to-C">
>>       <nml:relation type="serialcompound">
>>          ...
>>       </nmlserialcompound:relation>
>>     </nml:link>

I think you mean this instead:

      <nml:link id="urn:ogf:network:example.net:link_A-to-C">
        <nml:relation type="serialcompound">
           ...
        </nml:relation>
      </nml:link>

Your example above would not parse correctly.

>> and:
>>
>>     <nml:link id="urn:ogf:network:example.net:link_A-to-C">
>>       <nmlserialcompound:relation>
>>          ...
>>       </nmlserialcompound:relation>
>>     </nml:link>
>>
>> The advantage of the first syntax is that it is very easily extendable,
>> and it is still obvious for a parser to understand that it is some kind
>> of nml:relation, even if the particular type of relation is not known by
>> the parser.
>>
>> The advantage of the second syntax is that it is easy to create a
>> meaningful validator for each specific nml:relation.
>>
>>
>> I dislike both syntaxes, and was hoping for a syntax that would provide
>> both benefits.
>>
>> If I'm correct, the following syntax will do just that:
>>
>>     <nml:link id="urn:ogf:network:example.net:link_A-to-C">
>>       <nml:relations>
>>         <nmlserialcompound:relation>
>>            ...
>>         </nmlserialcompound:relation>
>>       </nml:relations>
>>     </nml:link>
>>
>> This adds a parent element to the relation elements, signifying that
>> <nmlserialcompound:relation>   is indeed a nml:relation. So even a parser
>> that has no knowledge about this particular nml:relation still knows
>> it's base syntax, while a parser that understands the details can still
>> use an meaningful syntax validator (such as XSD) to make sure the syntax
>> is correct.
>
> The solution with namespaces gives you that (nmlserialcompound:relation
> inherits from the base nml:relation). nml:relations only complicates the
> xml structure without giving too much.

I agree with Roman, the use of the 'relations' element is really not 
necessary here.

I am still not clear why you believe this element is necessary.  It is a 
'grouping' concept from what I can tell, but this does not add any 
inheritance into the sub elements except that of parent/child.  The 
concept of namepsaces gives you the inheritance that I think you want.

-jason

>
> Cheers,
> Roman
>
>> Would this do, and is this syntax acceptable to all?
>>
>> Regards,
>> Freek