This chapter presented the solutions for the Cancel an order use cases. It also presented a partial solution for Create new phone order. Complete the solution for the Create new phone order use case by adding view and data layer classes to the sequence diagrams. In Chapter 11 you developed architectural designs and CRC cards for two more use cases, Create order return and Record order fulfillment. Develop three-layer sequence diagrams for these two use cases. Update the design class diagram for the problem domain classes with method signatures from these use case designs. Compare this solution to what you developed in Chapter 11.