OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.


Help: OASIS Mailing Lists Help | MarkMail Help

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index]


I agree, except the standard to which you meant to refer was called RMDM (Reference Model for Data Management).  IRDS was Information Resource Dictionary System.


On 2016-09-26 16:14, Michael Kay wrote:

Meaning of “data model” in the XML world

I think that a data model in the first sense is the set of constructs (complex types, simple types, element declarations, attribute declarations, etc.) defined in the XML Schema specification.

I think that a data model in the second sense is a particular XML Schema. For example, the Geography Markup Language (GML) schema is a data model in the second sense.

Do you agree?


In the 1980s a popular concept was the 4-layer IRDS model. Each layer is a mechanism for describing the layer below. Your "data model in the first sense" (e.g. the relational model or the XML schema model) is at layer 2, and can be described using formalisms such as mathematical set theory which constitutes layer 1. Layer 2 is used to describe layer 3, which is your "data model in the second sense", that is the database or document schema. Layer 4 is the user data.

Michael Kay

Jim Melton --- Editor of ISO/IEC 9075-* (SQL)     Phone: +1.801.942.0144
  Chair, ISO/IEC JTC1/SC32 and W3C XML Query WG    Fax : +1.801.942.3345
Oracle Corporation        Oracle Email: jim dot melton at oracle dot com
1930 Viscounti Drive      Alternate email: jim dot melton at acm dot org
Sandy, UT 84093-1063 USA  Personal email: SheltieJim at xmission dot com
=  Facts are facts.   But any opinions expressed are the opinions      =
=  only of myself and may or may not reflect the opinions of anybody   =
=  else with whom I may or may not have discussed the issues at hand.  =

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index]

News | XML in Industry | Calendar | XML Registry
Marketplace | Resources | MyXML.org | Sponsors | Privacy Statement

Copyright 1993-2007 XML.org. This site is hosted by OASIS