Re: [xml-dev] Build applications using the "simplicity stack"

[Michael Kay <mike@saxonica.com>]

But I have yet a question. You wrote: "uniformity of data model and systems architecture across a system".

Actually I think I wrote "uniformity of data model and data representations".

By uniformity of data model I meant that all components of the system share the same understanding of the information that the system is handling. For example, a "flight" in one part of the system is the same thing as a flight in another part of the system, e.g. it doesn't suddenly become three flights just because three different airlines are selling it.

By uniformity of data representation I meant minimizing the number of different ways of representing the same data, e.g. in XML, in Java objects, and in SQL tables.

Michael Kay

Saxonica

Q: Do you mean uniformity *within* the data model and *within* the realm of representations; OR do you mean also a uniformity which *spans* across the gap between data model and representations, enabling clear alignments. The latter, by the way, was what I attempted to say (writing "establish the relationships between document content and system structure").

Hans-Jürgen

Michael Kay <mike@saxonica.com> schrieb am 11:00 Freitag, 4.April 2014:

On 4 Apr 2014, at 09:17, Hans-Juergen Rennau <hrennau@yahoo.de> wrote:

In response to Arjun Ray saying: "Data should be stored in formats appropriate to purpose. Systems are built to satisfy business requirements, not to propitiate theories."

Michael Kay wrote: "I think that kind of statement grossly undervalues the contribution that good systems architecture can make to business success."

Seen in the light of to what it responds, this is an amazing statement. Perhaps I misread it, but it suggests to me this thought: XML representation excels in the clarity and explicitness of structure; system architecture establishes important large-scale structures; XML representation can help to establish very clearly the relationships between document content and system structure - between document and large context, that is - and to align content items with items of system architecture.

I was not intending to suggest that a systems architecture has to be based on XML in order to be considered "good".

I do think that uniformity of data model and data representation across a system help enormously in ensuring the architectural coherence of the system, and an architecture based on end-to-end XML can help to achieve that goal.

Michael Kay

Saxonica