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

DEV475 Mastering Object-Oriented Analysis and Design with UMLWhy Use Analysis Mechanisms?Why Use Analysis Mechanisms?Oh no! I found a group of classes thathas persistent data. How am Isupposed to design these things if Idon’t even know what database we aregoing to be using?That is why we have a persistenceanalysis mechanism. We don’tknow enough yet, so we canbookmark it and come back to itlater.Analysis mechanisms are used during analysis to reduce the complexity ofanalysis and to improve its consistency by providing designers with ashorthand representation for complex behavior.Mastering Object Oriented Analysis and Design with UMLCopyright © 2003 Rational Software, all rights reserved 22An analysis mechanism represents a pattern that constitutes a common solution to acommon problem. These mechanisms may show patterns of structure, patterns ofbehavior, or both. They are used during analysis to reduce the complexity of theanalysis, and to improve its consistency by providing designers with a shorthandrepresentation for complex behavior. Analysis mechanisms are primarily used as“placeholders” for complex technology in the middle and lower layers of thearchitecture. When mechanisms are used as “placeholders” in the architecture, thearchitecting effort is less likely to become distracted by the details of mechanismbehavior.Mechanisms allow the analysis effort to focus on translating the functionalrequirements into software concepts without bogging down in the specification ofrelatively complex behavior needed to support the functionality but which is notcentral to it. Analysis mechanisms often result from the instantiation of one or morearchitectural or analysis patterns.Persistence provides an example of analysis mechanisms. A persistent object is onethat logically exists beyond the scope of the program that created it. The need tohave object lifetimes that span use cases, process lifetimes, or system shutdown andstartup, defines the need for object persistence. Persistence is a particularly complexmechanism. During analysis we do not want to be distracted by the details of how weare going to achieve persistence. This gives rise to a “persistence” analysis mechanismthat allows us to speak of persistent objects and capture the requirements we willhave on the persistence mechanism without worrying about what exactly thepersistence mechanism will do or how it will work.Analysis mechanisms are typically, but not necessarily, unrelated to the problemdomain, but instead are "computer science" concepts. As a result, they typicallyoccupy the middle and lower layers of the architecture. They provide specificbehaviors to a domain-related class or component, or correspond to theimplementation of cooperation between classes and/or components.5 - 22