A pre- and postcondition contract is a well-known style to specify an operation in the UML. In the UML, operations exists at many levels, from
System down to fine-grained classes, such as
Sale . Operation contracts for the
System level are part of the Use-Case Model, although they were not formally highlighted in the original RUP or UP documentation; their inclusion in this model was verified with the RUP authors.[1]
[1] Private communication.
Inception Contracts are not motivated during inceptionthey are too detailed.
Elaboration If used at all, most contracts will be written during elaboration, when most use cases are written. Only write contracts for the most complex and subtle system operations.