How to examine a Data Model or Dataset in the Catalogue

Owned by David Milward
Last updated: Dec 06, 2016
2 min read

As explained elsewhere there are many different systems to classify data, all of which have merits and failings that are continually being debated. The metadata exchange uses a very simple system – arguably a meta-language or domain specific language (DSL) – that takes common elements from many of these different modelling and classification systems.


At the top level a sets of data elements is called a “Model”, so that all the data elements that are used in a particular use case or domain can be grouped into a single “model”. Within that model data elements can be grouped together into containers, these we call “Data Classes”, but they could equally well be called “Entities” or even “Concepts” since in many cases they do in fact directly represent some concept in the real world.


We have given Data Classes the ability to have some degree of hierarchy and containership, so a Data Class can contain other Data Classes as well as containing Data Elements; “Data Elements” can be viewed as singular atomic data items, such as a number.  Each Data Element will have an associated type that we call a “Data Type”.

Step-by-step guide


  1. Click on the model or dataset in the home page.





  2.  You should now get the detail view of that model:





  3. The different model elements are represented by different icons

 Data Model - which is a specific, versioned, group of data elements

 Data Class - A Structured group of data elements inside a model, and which can be related to another Data Class, by inheritance or containment

 Data Element - An atomic unit of data, sometimes called an attribute, field or property.

 Data Type - A type or classification descriptor for a data element. Data Types can be sub-typed into enumerations, primitives and measurement units, which get slightly different icons.

...................  Primitive Type - depends on the model, not needed when model is purely conceptual.

...................  Enumerated Type - This element is composed of a restricted list of enumerations

...................Enumeration - part of above Enumerated Type

................... Measurement Unit - type probably based on a primitive, but which represents a common measurement unit.

 Business Rules, also called validation rules, these can be attached to elements or to relationships. mostly we use regex or groovy code as a definition, but could be OCL or QVT type constraint.

 Assets (Could be imported files, such as csv or XML files describing the model)

 Deprecated Item.