Re: [xquery-talk] Serialization of XDM

["David A. Lee" <dlee@calldei.com>]

I agree with your sentiment
"if not you can serialize and parse them without loosing any information."

but not the implication.

This is (partially) true, but the problem with this is there is not *standardized* way to do this.
For simple things like say sequences of nodes, you can wrap them in a document.
Or for say integers you can wrap them in something like an <integer> tag.
The problem is there are a *million* ways to do it ... which means no vendor has agreed, which leaves it up to the programmer to do it.
Which means you have to cooperate on both sides of the equation, and since there is no standardized way to do it, different toolkits or pieces are almost certain to do it differently, and possibly in ways that are difficult to parse.

By "partially" I am refering to the interesting XDM type of attributes,  which noone can agree at all on how to serialize.
( although you could stick them in an element ... )

So to make this actually work in practice, you must control both sides of the partnership, and the serialization in between, and also pass "metadata" either by convention or something to make it all work.   A programmer, to say take the output of one XQuery, store it in a file, then put it back into an external varialbe of another XQuery invocation has to do quite a lot of work, the sort of work that XML was designed explicitly to *avoid having to do*.

Even defining a standardized schema for 'wrapping' XDM content unambiguously in a XML document would be a huge value,
even if the result wasn't pretty, at least it has the potential for interchange.

But lets not talk about function items ... I have no clue where to go with those ....

David A. Lee
dlee@calldei.com  
http://www.calldei.com
http://www.xmlsh.org
812-482-5224

Florent Georges wrote:

David A. Lee wrote:

  Hi,

  

There is no standard or even 'community accepted' way of
serializing XDM
    

  While I used to think this is a problem, more and more I think
it is not (or at most a little problem we can live with.)  XDM
is a convenient (and needed) data structure to work with within a
piece of code (like a stylesheet or a query.)  (BTW this is a
pity that XProc is not based on XDM, IMHO)

  But if you want to pass information between two different
pieces of code (like between a query and a stylesheet) you can
just restrict yourself to nodes.  If you want to pass a sequence
of integers, you can instead pass an element containing elements
the content of which are integers...

  So the simple rule: independent pieces of code set boundaries
between which you can only pass nodes, or even document nodes.
That's what XML means, after all.  If you use compatible
processors, you should then be able to configure them to pass
those nodes in an efficient way, and if not you can serialize and
parse them without loosing any information.

  Just my two cents....

  Regards,