RE: [xml-dev] XML 2.0

["Rick Jelliffe" <rjelliffe@allette.com.au>]

What is the difference between a document with multiple roots and a
document with a single root?  One start tag and one end tag.

What is the benefit of forcing a single root? Catching errors where the
document ends prematurely but on a /*/* boundary.

In SGML/HTML, where there is tag omission, having a single rooted document
was an absolute necessity. XML does not have this, because of the WF
rules. However, the value that a multi-rooted documents gives seems so
slight as to be non-existent. All multi-rooting does is push the
requirement for checking that a transmission has completed successfully to
the next lower layer of the protocol stack, and it is something that needs
to be proved that the next lower layer (e.g. HTTP) does correctly handle
the kinds of incorrect document terminations that XML's single root model
does, surely.

Cheers
Rick Jelliffe

Michael Kay said:
>> A corollar of having multiple roots in one document is to
>> define a syntax for naming multiple father-children relations.
>>
>> As with a database, each element should be accessible
>> directly (efficient use of '//element') while oriented
>> relations (child to father or father to children) are used to
>> access other elements.
>>
>> With XML 1.0, we have to add id attributes to implement this
>> and there is no specific syntax. XML 2.0 should develop a
>> richer syntax for axes.
>
> Sounds like you're reinventing the network (Codasyl) model. It's about
> time
> it had a revival. I think you're right - the strict hierarchical approach
> of
> XML is fine for messages and for documents, but it really isn't ideal for
> persistent data. The poor handling of relationships outside the hierarchy
> has always been a weakness.
>
> Michael Kay
> http://www.saxonica.com/
>
>
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