Page 145 -

128 Chapter 5 System modeling

Medical Receptionist PRS

P: PatientInfo D: MHCPMS-DB AS: Authorization

Login ( )
OK

Alt
[SendInfo]
UpdateInfo( )
Update PRS (UID )
Authorize (TF, UID)
Authorization
Update (PID)
Update OK
Message (OK)

[SendSummary]
UpdateSummary( )
Summarize (UID )
Authorize (TF, UID)
Authorization
:Summary

Update (PID)
Update OK
Message (OK)

Logout ( )

Unless you are using sequence diagrams for code generation or detailed docu-
Figure 5.7 Sequence
diagram for transfer mentation, you don’t have to include every interaction in these diagrams. If you
data develop system models early in the development process to support requirements
engineering and high-level design, there will be many interactions which depend on
implementation decisions. For example, in Figure 5.7 the decision on how to get the
user’s identifier to check authorization is one that can be delayed. In an implementa-
tion, this might involve interacting with a User object but this is not important at this
stage and so need not be included in the sequence diagram.