to the message by identifying the operation that implements the named message, executing this operation, and then returning control to the caller.This can done by simulating the object interactions.
Figure 6.13 shows messages that may be exchanged between three objects; library user,library item and library staff.The library user makes use of issue and return operations implemented in the library item,and the library operator makes use of the library item's acquire,catalogue and dispose operations.The library operator can also send register and query messages to the library user object. These are generalised messages which can be developed into detailed messages with further refinement.
The object operations are shown in Figure 6.14-6.16. Implicit operations associated with accessing and modifying attributes are not shown.
Rumbaugh et al.(1991) describes an additional approach to identifying operations.We do not have the space here to describe the process in detail