The relationship of class in UML

In theUML, a class diagram is a type of static structure diagram that describes the structure of a system by showing the system's classes, their attributes, and the relationships between the classes.

• Instance Level Relationships have Association, Aggregation and Composition.

  Composition is a special form of aggregation where in each part may belong to only one whole at a time. When the whole is destroyed, so are its parts. Aggregation is a special form of association as well that specifies a whole-part relationship between the aggregate (whole) and a component part.You state an association at the class level.Association is An association between classes indicates that objects of one class may be related to objects of the other class

• Class Level Relationships have generalization.

  The generalization relationship is also known as the inheritance or "is a" relationship.

• General Relationship have dependency.

  A dependency exists between two defined elements if a change to the definition of one would result in a change to the other. A dependency can be between instances, classes, or both.

Note:In the class diagram, there the arrow always point to the supplier.

the different of Operation and method in OO

In OO terms ,the operation and method have different definition. the Operation is an aggregation of a serial procedures, and each procedure is named method. So ,as BA, when your extract some imported characters of business logic from stakeholders, you should distinguish them. you take each operation and ask stakeholders what procedure they use to carry it out. You document the procedure as a method.