4d.+Validation+&+Discussion+of+System+Design+Models

=__System Design Work Validation & Discussion (Stephen Slaughter) __=

===Our System Design work for the OnCD application included system sequence diagrams, state diagrams, and the Design class diagram. ===

===Each team member drew sequence diagrams for the critical use cases which we were responsible for specifying earlier in the project. Each of our sequence diagrams had boundary objects, controllers, and domain objects with responsibilities for processing the use cases. Our sequence diagrams differed in terms of the domain objects and their respective responsibilities because each of us specified different use cases. We used Google Docs’ drawing tool to illustrate our diagrams because we liked its colorful diagram elements and user friendliness. ===

===For the state diagram task, each team member picked either a domain object or use case to model. Lucheng and Stephen decided to model use cases instead of domain objects because they each felt the domain objects for this application were not complex and reactive enough to warrant drawing a state diagram. Lucheng and Stephen used Google Docs’ drawing tool again to model their state diagram while Joe decided to model his state diagram using Powerpoint.===

===For the Design class diagram, Stephen decided to use Visio to refine and build on the model previously specified in the Analysis phase. All of the domain model’s classes were preserved in the design class diagram; still more classes were added to represent those identified in the sequence diagrams and state diagrams. Reference attributes were identified through the associations of classes, along with regular attributes which had some logical justification for addition to the model. Cardinality was chosen according to obvious semantics of the model.===