[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XML Schema as a data modeling tool
Well, let me start by pointing out the drawbacks, seen very severely on a project I did some consultancy for, where they had indeed used XML Schema for a large scale enterprise data model: (A) XSD isn't very good at modelling relationships. It's a hierarchic model, whereas the real world is a network. Modelling relationships other than aggregations therefore involves some arbitrary decisions on representation, which you don't really want in a conceptual data model. (B) XSD is designed for representing messages rather than for creating an enterprise data model, and it's very easy to get the two confused. It might be that every employee has a salary history, but that doesn't mean the salary history has to be part of every message concerning the employee. The relationship between the conceptual reference model and the design of individual messages can be quite indirect. There are really several separate problems here: (a) XSD was designed for message/document design, not for conceptual modelling, (b) designing a family of schemas for a large set of message types, with reuse of components across all the message types, is itself rather difficult and there's very little in XSD that makes it easier, (c) message design has to take the process model into account, not just the data model. Michael Kay Saxonica On 30 Sep 2013, at 09:27, Hans-Juergen Rennau wrote:
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