Re: [xml-dev] Serialization of XDM

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

Here are some use cases I am imagining.  They may well lead to different 
ideal representations ...

1) Program to Program interop
XDM producer program produces a set of values to be used by an XDM consumer

Example:  XQuery produces a sequence of nodes to be passed into an XSLT 
or XQuery external variable in a different environment.

2) Internal XML Program Interop
"Orchestrating" or "Scripting" programs that want to expose their 
connectivity in a standard way.

Example: XProc "pipes" are a subset of XDM, (sequence of Documents).  
This includes the input and output of the processor as a whole.
It would be nice if XProc implementations would accept a standard 
representation for both input and output, as well as expose a standard 
implementation for interconnectivity between steps.  This would allow 
XProc engines to interop with different vendor's step definitions 
independently of the implementation of the engine.  It would also allow 
a standard for supplying data to XProc and outputting data from XProc 
(sequence of nodes).

Example:  A vendor's XQuery accepts XDM values as declared external 
variables.  There is no standard on how these may be passed into XQuery.
An XDM Serialization standard would allow standards on how to say supply 
a file containing XDM values to any XQuery implementation.

3) XML to NON-XML Program interop
If an XML program (say XQuery) outputs XDM data which is to be consumed 
by a NON-XML program (say a program that reads text or CSV),
it would be very nice if there was a standard format to produce, or 
atleast a standard way to convert such a format.
This is a similar but distinct case from #4


4) Standard "User Friendly" output of XDM  processes
Current xquery and xpath implementations vary on how they output XDM 
values (such as non-documents).
Example.  What is a standard output of     '1 to 10'  ?
It would be very useful if vendors could agree on at least one standard 
for this.  Typical examples I've seen are space separated, or newline 
separated output.







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



Mukul Gandhi wrote:
> Hello David,
>    I think, I agree with you, that it's a good idea to be able to
> serialize an XDM instance into some form. I would prefer an XML format
> for the serialized XDM instance. i.e, perhaps we could define a XML
> Schema for XDM serialization format.
>
> But I am keen to know, what could be useful use cases, for XDM
> serialization? I can think of interoperability of XDM instances
> between vendros, as on the use cases for XDM serialization. But would
> this really give some/any value to users (say query[XQuery] and
> stylesheet[XSLT] writers)?
>
> It seems to me, XDM serialization is like aiming to go to mars at this
> point of time :)
>   
>