3.1 From Hierarchical to Object-Relationship Data Model

RESQML now uses an object-relationship model to organize its data objects.

Version 1.1 used what was essentially a hierarchical data model. The World Wide Web Consortium (W3C) does not explicitly state that XML is hierarchical, and the XML specification includes some capabilities that are not purely hierarchical. Yet, in v1.1, all semantic information was assembled in only one XML instance consisting of one XML file, with hierarchical “implicit” XML containment to associate the data objects together. An optional, associated HDF5 file contained large sets of numeric data.

However, because the relationship between components of an earth model are inherently complex (not truly hierarchical), the RESQML Special Interest Group (SIG) members determined an earth model could be more accurately represented with an object-relationship model. This change allowed the components of the earth model to be represented as separate data objects and the relationships among them to be more accurately represented as parent-child, with one-to-many or many-to-may relationships.

An important point: with an object-relationship data model, the child data objects can now be exchanged without their parent, which supports the exchange of only those parts of a model that have changed, what RESQML refers to as partial model exchange. (For more information on partial model exchange, see the workflow use cases in the RESQML Business Overview and Use Case Guide.