SDB_Structure - Complex data type

A structure defines a complex data type, which represents a view to a given object type. The complex data type definition provides usually a subset of the characteristics of the object type considered.

A complex data type represents the structural part for an object type, while the functional part is defined in the more specific class definition. An ODABA data type definition contains, however, also dynamic model elements, which allow defining reactions on system or user-defined events.

Complex data type properties are defined as properties of different categories:

• base types (for generalization)
• attributes (for characteristics)
• references (for parts)
• relationships (for associations)

• Other members defined on data type level are keys. A complex data type may define any number of keys based on attribute values of the data type.

Complex data type of different categories can be defined depending on the purpose of use. Usually, complex data type represent user-defined types. Internally, however, key data types are created from key definitions. System data types refer to complex data type definitions provided by ODABA. View data types are complex data type, which are implemented as views.

One may refer to complex data type as type of different sort of members. Before being able to store instances for a complex data type, the complex data type itself and all types referenced by its members have to be be checked. In order to store instances, the complex data type state must be set to ready.