Database and Expert Systems Integration - Information Systems Reengineering, Integration and Normalization - page 312

Fig. 8.3 An example of a
relation in the frame model
metadata

Attributes:
Name: Method(name)
Sex: Method(sex)
Father: Method(father)
Mother: Method(mother)
Methods:
name (): Text; {............}
sex (): Text;{............}
father (): Text;{............}
mother (): Text;{............}

store data in its own database. All the three classes use the same structure. Combin-
ing these three types of objects within the inheritance hierarchy structure enables the
frame model metadata to represent and combine heterogeneous knowledge.
The structure of a class includes three main parts: attributes, methods, and con-
straints. An attribute may be an ordinary attribute as in the EER model, a complex
attribute in the sense that it is structured or it may represent a set, or a virtual attribute
defined in the method part. A method can represent the behavior of the class, or give
definitions of a virtual attribute, a deductive rule, or an active rule. Constraints rep-
resent additional knowledge concerning the attributes, the methods, and the class.
Every class includes basic frame information to represent the class entity, called the
header. The header of the class structure includes class name, primary key, parents,
and a description. The Class_Name is a class identifier, that is, a unique name de-
fined by the application developer. The Primary_Key assists the system to define the
semantics of an object identifier. The frame model metadata supports a mechanism
to deal with the Primary_Key and object name to ensure the object name is a unique
name in the application. Parents represent the generalization/specialization relation-
ship between the current class and its super class. Each class also has a Description
document, which contains a textual description of the class.
Figure 8.3 is an example of a relational table and its correspondent coupling class
structure in the frame model metadata for illustration.

Relation Person in database
Field name Type Field

Name Character 15

Sex Character 1

Father Character 15

Mother Character 15

Mapped correspondent class in the frame model metadata
Class Name: Persons

The database coupling class mirrors the database structure (i.e., schema), but does not
include all of the data in the database. The reason is that it is difficult to hold a large
amount of data in the integration system. The expert system coupling class repre-
sents the communication that must be performed when data passes between the frame
model metadata and an expert system. The expert system coupling class includes: