Three Access Language Paradigms

[Jonathan Robie]

At 03:14 PM 11/18/97 -0500, Joe Lapp wrote:
 
>I'd like to present still another form of access language.
>This approach is based on a different way of thinking about
>documents.  Instead of asking document repositories to look
>like XML documents to the external world, we only ask that
>the repositories speak XML with the external world.  DTDs
>would be defined for the protocols that repositories might
>care to speak.  The DTDs would define the structure of the
>protocol messages rather than the structures of documents.
>One repository might speak several protocols (e.g. 'Patient
>Records Protocol V.152' or 'Bank Transaction Protocol 2A').
>If the repository were capable of containing arbitrary XML
>documents, the repository might speak a specific protocol
>called 'XML Document Protocol V.1.0'.
 
This is an interesting idea, and would allow queries to be defined in an
SGML/XML-aware syntax. For instance, if we want to get "billables" from a
patient record system, we could ask an external system like a relational
database for this information using a query defined in an SGML-aware language:

billable { patient_id = 7537053 }

The external system would have to have a mapping between the DTD structure
that defines the abstract model for this protocol and the internal data
structures used on that particular system. In this case, it would have to
know what a "billable" is, where to find it, and how to find those
"billables" that belong to the patient with this particular patient id.
Offhand, this seems like a reasonable amount of effort to ask people to do
in order to interface their databases to document management systems.

On the repository side, one query could be used to support any external
system that uses this particular DTD, and general-purpose techniques could
be used to manage any virtual document. On the database / external system
side, each DTD abstraction would be a separate programming project, but I
don't really see any way around that.

I'll have to think about it, but at first blush, I like it.

Jonathan
________________________________

Jonathan Robie
Email: jonathan at texcel.no
Texcel Research, Inc. ("http://www.texcel.no")


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