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object named CrystalReports without an interface class or some facade to encapsulate potential changes or failures in the control. As a result of directly modeling calls to Crystal Reports, function calls have to match exactly what Crystal Reports requires. However, suppose that later the project requires the use of ActiveX communications with Access 97 or beyond. The sequence diagram in Figure 7.2 would have to be changed, as well as every other diagram that used Crystal Reports. What's more, every place in the Visual Basic code where Crystal Reports is referenced would also have to be changed. In the end, this costs you and the organization more money than necessary because you could have wrapped the calls to Crystal Reports behind an object that implements the IReporting interface class. |
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Figure 7.2.
The wrong way to implement third-party controls such as Crystal Reports in your
sequence diagrams. |
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Figure 7.3.
The right way to implement third-party controls such as Crystal Reports in your
sequence diagrams. |
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