DEV475 Mastering Object-Oriented Analysis and Design with UML ...

DEV475 Mastering Object-Oriented Analysis and Design with UMLLayering ConsiderationsLayering Considerations• Level of abstraction• Group elements at the same level of abstraction• Separation of concerns• Group like things together• Separate disparate things• Application vs. domain model elements• Resiliency• Loose coupling• Concentrate on encapsulating change• User interface, business rules, and retained data tendto have a high potential for changeMastering Object Oriented Analysis and Design with UMLCopyright © 2003 Rational Software, all rights reserved 16Layers are used to encapsulate conceptual boundaries between different kinds ofservices and provide useful abstractions that make the design easier to understand.When layering, concentrate on grouping things that are similar together, as well asencapsulating change.There is generally only a single Applicationlayer. On the other hand, the number ofdomain layers is dependent upon the complexity of both the problem and thesolution spaces.When a domain has existing systems, complex systems composed of inter-operatingsystems, and/or systems where there is a strong need to share information betweendesign teams, the Business-Specific layer may be structured into several layers forclarity.In Architectural Analysis, we are concentrating on the upper-level layers (theApplication and Business-Specific layers). The lower level layers (infrastructure andvendor-specific layers) will be defined in Incorporate Existing Design Elements.5 - 16