Bug #428
closedeml-constraint overlaps with packaging concepts
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Description
The current incarnation of eml-constraint allows the enumeration and definition
of integrity constraints that apply to entities. These are currently drawn from
the relational model, including UNIQUE, PRIMARY KEY, FOREIGN KEY, and CHECK
constraints. It may also be extended to include other types of relationships
between entities that are not part of the relational model.
The "triple" element allows us to create arbitrary relationships between
identifiable objects in EML, and is used for associating data with metadata, and
groups of metadata and data objects together as a "package". This usage is very
similar to the relational model, in that it allows us to define 3-valued tuples
in a graph structure. Constraints between entities could conceivable be modeled
using this infrastructure, probably with some modifications to the concept of a
"relationship".
So, the question arises. Should we try to develop a unified approach to the
specification of constraints and the specification of packages? It might be
more elegant, but possibly at the cost of simplicity and ease-of-use. My gut
feeling is that this is not something we whould pursue, but would like to hear
other people's reasons for or against it.
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