Re: [xml-dev] [OT] Re: [xml-dev] Lessons learned from the XML experiment

[Michael Kay <mike@saxonica.com>]

> 
> Further, you made the claim that "XML is not designed for nodes". If
> you are unwilling to defend this claim, it, too, must be rejected.
> 

No, let's be quite clear. You, David, made the claim that XML is designed for nodes, and Uche rejected that claim. The onus is on you to prove your claim, not the other way around.

I don't know exactly what "designed for nodes" means, but it suggests to me an idea that the designers of XML had tree-based data models firmly in mind as an influencing factor during the design process.

It's always difficult to discover what designers were thinking when they produced a specification, but with XML it's easier than usual because

(a) the specification contains a list of design goals, (section 1.1) and

(b) one of the authors of the specification, Tim Bray, produced an annotated edition here:

http://www.xml.com/axml/testaxml.htm

Now, in the list of goals, the closest we come to any mention of a data model is the goal "It shall be easy to write programs which process XML documents"; but Tim Bray's gloss on this statement makes it clear they were thinking that it should be easy to write an XML parser. So there is absolutely nothing in the spec about the ease of writing XML-consuming applications. Which is a rather remarkable omission, and puts XML in very stark contrast to JSON.

Similarly, in the annotated specification, mentions of trees, nodes, and data models are conspicuous by their absence.

Now I think we can confidently say that the designers of XML were well aware of the possibility of modelling a document as a tree of nodes; we must therefore assume that the absence of any mention of such a model is deliberate. Perhaps the designers had a tree model at the back of their minds and felt it could be added later, but that would be speculation; all the evidence is that they consciously decided data models were out of scope. Which in my view is unfortunate, but that's not the point.

We have a tradition on this list of showing each other respect, and I think you fell short of that standard in your response to Uche.

Michael Kay
Saxonica