RE: [xml-dev] RE: Caution using XML Schema backward- or forward-compatib

["Len Bullard" <cbullard@hiwaay.net>]

If one approached it as a complex systems inquiry, you are examining the
critical value where a consumer/service complex transitions from receiver to
system/application.   The question of validation is somewhat irrelevant.  An
application can consume a data service without any a priori knowledge of the
service semantics.  That is why we use XML or its analogs.

IOW:

1.  What is the context? Exchange.  Yes.  Processing.  Yes.  Validation is a
process.  Use?  This implies some act not possible with data alone.  The
question is do all parties/applications/clients/services to the transaction
share the same intent?

2.  Means vary and uses vary.  The interesting question from a semantic
perspective is how many uses can be made by how many different means and the
results would be the same?  This is similar to the philosophical but
enlightening question, what is proof of intent?

With regards to the semantic:  at what point does some means, say RDF,
become functionally equivalent to an application?  IOW, when specifying a
system at some detail of specification, the specification becomes the
system.  At that point, versioning is versioning of an application (say,
client program) not versioning of the data it consumes.

You can certainly apply versioning to data instances because it is in most
cases some sequential or hierarchical naming scheme for the instances of the
validating artifact.  The set of relationships to the versioned
clients/applications is possibly infinite but practically within the phase
space.  The 'sweet spot' is at or near the critical transition between
specification and application.

I agree with Thomas Lord.  The shared definition for 'semantic' is be the
critical variable.  This is the phase transition variable, Roger, at which
the declared specifications transit into functional applications.

len


From: Costello, Roger L. [mailto:costello@mitre.org] 
 
Hi Len,

> Was there a point to that other than to beg
> the use of semantic web tech for web services?

No, I am not pushing any semantic web techniques. WSDL documents focus
on describing a web service based on the syntax of the data.  For a
client to use a web service, it needs to also know the semantics.
There are many ways to describe the semantics.

> May I assume that the entire focus of this is not versioning for data
> exchange, but versioning for applications implemented AS web services
where
> the definition of web services has X Y and Z components?

Yes, I narrowed the problem to data exchange between a web service and
clients, where the clients are unknown to the web service (the web
service is available to anyone).  How clients use the data retrieved
from the web service is variable and unknown.  

The issue is: how is versioning related to validation?  

I assert that a data versioning strategy should be decoupled from a
data validation strategy.  Versioning should be driven by business
requirements, not technology limitations.

Your thoughts?

/Roger
 

-----Original Message-----
From: Len Bullard [mailto:cbullard@hiwaay.net] 
Sent: Monday, December 31, 2007 10:47 AM
To: Costello, Roger L.; xml-dev@lists.xml.org
Subject: RE: [xml-dev] RE: Caution using XML Schema backward- or
forward-compatibility as a versioning strategy for data exchange

Umm..  cool but you just restated pretty much the nut of the
discussions for
the design of XML originally.  Was there a point to that other than to
beg
the use of semantic web tech for web services?

A lot of applications don't need it.

May I assume that the entire focus of this is not versioning for data
exchange, but versioning for applications implemented AS web services
where
the definition of web services has X Y and Z components?

len


From: Costello, Roger L. [mailto:costello@mitre.org] 

A web service may also make artifacts available to clients to assist
them with "understanding what they get":

(a) A document (or documents) to help clients understand the data they
retrieve

There are many technologies to achieve this, including prose (i.e.
create a web page that client developers can read), data dictionary,
RDF/S, OWL.



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