An overview of the object-oriented entity-relationship model (OOERM)

The object-oriented entity-relationship model (OOERM) and its associated diagramming technique (OOERD) is presented as a natural extension to the ER approach for modeling the dynamics of entity classes. In addition to modeling static properties, OOERM incorporates concepts from the object-oriented programming (OOP) paradigm to model operational properties of entities. Relationships between entities are used in message passing to allow an entity to access the attributes and operations of other related entities. An OOERD is a graphical abstraction of an underlying OOERM schema description which is used to depict the dynamics of message-passing between entities. The synergy between OOP and ER concepts is also discussed. The syntax and semantics of the OOERM language are informally presented, along with the graphic notations and icons of OOERD. Structural and operational modeling in OOERM is illustrated through examples