Oct 22, Ron McFadyen1 Design Class Diagrams n Class diagram with – classes – associations – attributes – methods – navigability – interfaces, attribute types, dependencies n we are designing software classes now - no longer conceptual Ch 19

Oct 22, Ron McFadyen2 analysis design Figure 19.2

Oct 22, Ron McFadyen3 An interaction diagram showing a register sending a makeLineItem message to a sale, implies that the Sale software class must have a makeLineItem method Usually don’t show create, accessor, or mutator methods uninteresting Messages imply Methods (figure 19.4)

Oct 22, Ron McFadyen4 Figure 19.8 The navigability arrow (also called a navigability adornment) indicates that a Register object is connected uni-directionally to Sale objects … the Register class has an attribute, currentSale, pointing to a Sale object Do we have any interaction diagrams showing a message from a Sale object to a Register object? Navigability

Oct 22, Ron McFadyen5 Navigability: in the UML, an association line that has no specific navigation indicated, is considered to be bidirectional. The directed arrow is unidirectional, and shows navigability. The above shows that a register object can navigate to a sale object: I.e. a register needs to know the sale object, but not the other way around. Register can send a message to a sale, sale can respond, but doesn’t initiate. In an OO language, Register will have an attribute that references a Sale instance

Oct 22, Ron McFadyen6 In Figure 19.10, we see the result from analyzing all interaction diagrams for navigability.

Oct 22, Ron McFadyen7 In Figure 19.11, we see additional dependencies shown … the dashed arrow line … register and sale have visibility to ProductSpecifications … register knows of a product due to the lookup in the catalogue and a sale receives a product specification in the makeLineItem message

Oct 22, Ron McFadyen8 Figure 20.6 MultiObjects

Oct 22, Ron McFadyen9 Figure 20.6 MultiObjects Product catalog will contain the product specificaitons, and so the find is implemented within the Product Catalog. Sale will contain the sales line items, and so the add is implemented within the sale.