USER SYSTEM FIGURE 90.5 RBS information model information model for the RBS is shown in Fig. 90.5. Entities(shown as rectangles)represent"things"or " objects"in the application domain Entities may be established by considering principal nouns or noun phrases in the application domain Entities have attributes associated with them which express the qualities of the entity. Entities participate in relationships; these are shown as diamonds in the entity-relationship diagram Relation hips may be determined by considering principal verbs or verb phrases in the application domain. Relationships have cardinality associated with them and entities may participate conditionally in relationships. Finally, there are special kinds of relationships which show hierarchical relationships between objects Essential Modeling The essential model consists of a number of graphical components with integrated textual information. Figure 90.6 shows the object collaboration model for the RBS. This model depicts how a collection of objects or entities can communicate(by exchanging messages)to perform the proposed system functions. An event list is part of this model; it shows what responses must be produced for a given external stimulus. UTTON 阳E MUTING CONTROLLE SYSTEM RESPONSE outton depressed. 1, Mute audio syster n-mute audio system FIGURE 90.6 RBS object collaboration model. e 2000 by CRC Press LLC© 2000 by CRC Press LLC information model for the RBS is shown in Fig. 90.5. Entities (shown as rectangles) represent “things” or “objects” in the application domain. Entities may be established by considering principal nouns or noun phrases in the application domain. Entities have attributes associated with them which express the qualities of the entity. Entities participate in relationships; these are shown as diamonds in the entity-relationship diagram. Relation￾ships may be determined by considering principal verbs or verb phrases in the application domain.Relationships have cardinality associated with them and entities may participate conditionally in relationships. Finally, there are special kinds of relationships which show hierarchical relationships between objects. Essential Modeling The essential model consists of a number of graphical components with integrated textual information. Figure 90.6 shows the object collaboration model for the RBS. This model depicts how a collection of objects or entities can communicate (by exchanging messages) to perform the proposed system functions. An event list is part of this model; it shows what responses must be produced for a given external stimulus. FIGURE 90.5 RBS information model. FIGURE 90.6 RBS object collaboration model