Types of relationships• Association• Super-sub structure (generalization hierarchy)• Aggregation and part of a structure
Association• Represents physical or conceptual connection between 2 or more objects• Binary association – Line connecting 2 classes• Ternary and higher order association – Diamond connecting to a class symbol by line• Association name is written above or below the name• Includes name of the role
Cont..• Identifying association• Common association pattern• Eliminating unnecessary association
Identifying association• Begins by analyzing the interaction among classes• Ask following questions – Is the class capable of fulfilling the required task by itself – If not, what does it need – From what other class can it acquire what it needs• Guideline – Dependency between 2 or more classes • Association corresponds to verb or prepositional phrase – Reference from one class to another • Implicit or taken from knowledge
Common association pattern• Location association – Ex: next to, part of , contained in• Communication association – Ex :talk to, order to operator customer order
Eliminate unnecessary association• Implementation association – Defer implementation specific association to design phase – Not concerned about relationship among business objects• Ternary association – Complicate the representation – Req • Restate ternary association to binary association• Directed actions or derived association – Can be defined in terms of other association – Leads to redundancy – Ex: Grant parent of raman abi parent of parent of raman murugan abi
Super-sub class relationships• Generalization hierarchy• Represents the inheritance re
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