Information Models and System Tables

Clients access the data in the Rochade repository through subject areas. Each subject area is based on an information model that describes a real-world issue and its logical relationships through item types, attributes, and links.

While clients use the names of item types and attributes (as defined in the model) to access the data in the repository, the Rochade Server internally uses only numbers as identifiers. This is the technique that makes it possible for Rochade users to address item types and attributes with intelligible names rather than cryptic numbers.

The assignment of the item type and attribute names to their internal numbers is handled by so-called system tables. Rochade uses these system tables:

• DOCTYPS contains the external names and internal numbers of all item types that are available to a user after loading the system table.
• CHAPTYPS contains the external names and internal numbers of all binary, link, namespace, and text attributes in a subject area.
• LINKTYPS contains the link qualifiers and the internal numbers of the item types to which the link qualifiers refer.