Identifying object relationships ,attributes ,

methods,

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

customeroperator

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:

raman abiGrant parent of

raman abiparent of

muruganparent of

Super-sub class relationships

• Generalization hierarchy

• Represents the inheritance re