Software Systems Design – 4 Class Diagrams (dynamic) Klaas Sikkel Software Systems Design - 4

Today’s topic Software Systems Design - 4

Contents From use cases to class diagrams “Analysis class diagram” Collaborations Communication diagram Use case class diagram “Analysis class diagram” Integration of use case class diagrams Further analysis Software Systems Design - 4

Positioning in the design thread Part 4 (this lecture) gives a more structured approach to deriving a class diagram. However, it’s hard to apply if have no experience with class diagrams Therefore we did Part 3 (static class diagrams) first, so that you have some idea about the entity classed that could be involved. Software Systems Design - 4

Agate Ltd. (Case A in Bennett et al.) Agate Ltd. runs publicity campaigns. For one client there can be multiple campaings Each campaign consists of a number of different clients Software Systems Design - 4

Use case Adding a new advert to a campaign Bennett Fig. 7.13 Software Systems Design - 4

A Collaboration Bennett Fig. 7.15 Software Systems Design - 4

A Collaboration Boundary Control object object Entity objects Software Systems Design - 4

BCE Objects/Classes Boundary object: provides interface with the outside world Control object: implements the logic involved in realising this use case Entity object: ‘regular’ object inside the systems Software Systems Design - 4

Communication diagram (1) Bennett Fig.7.16 Software Systems Design - 4

Communication diagram (2) Bennett Fig. A3.2 Software Systems Design - 4

Corresponding class diagram (use case class diagram) Bennett Fig. A3.3 Software Systems Design - 4

Communication diagram notations (1) Standard Com.d. notation BCE notation boundary / control / entity object :Campaign Software Systems Design - 4

Communication diagram notations (2) *: loop; repeat message for all instances Sequential numbering of messages 1, 2, 3, … n Hierachical numbering of messages 3, 3.1, 3.1.1, 3.1.1.1, 3.1.1.2, 3.1.2, etc Software Systems Design - 4

BCE style with hierachical numbering Bennett Fig. A3.11 Software Systems Design - 4

Use case class diagram Bennett Fig. A3.12 Software Systems Design - 4

Other use case CDs (only entity classes) From Bennett, Figs. 7.17, A.6 Software Systems Design - 4

Combined class diagram (“Analysis class diagram”) Bennett Fig. A3.13 Software Systems Design - 4

Overview of method For relevant use cases 1.1. Get extended use case description 1.2. Design communication diagram 1.3. Derive use case class diagram Combine use case CD’s into analysis CD Improve analysis class diagram 3.1. Verify correctness (does is match the case description) 3.2. Add further details (data elements, further use cases) Software Systems Design - 4

Overview of method (contd.) 3.1. Verify correctness (does is match the case description) We will do this in the lab exercise 3.2. Add further details (data elements, further use cases) See Bennett for an example Software Systems Design - 4

Static vs. Dynamic Class diagrams Static (D-3) Abstracts from methods More detailed semantics of generalization A model of information about the real world that should be represented in the system Dynamic (D-4) Includes methods Abstracts from data types and generalization details Constructed by analysing how the system realizes various use cases Software Systems Design - 4

Exercise Service department of internetshop RedHot: handling of products that need repair If a product is broken, the customer calls the Customer Service. An employee creates a service record. The customer receives an e-mail with instructions for sending it in, and label for sending a parcel free of charge. Software Systems Design - 4

Draw comm. diagram for this use case Actor action System response 1   2 Displays list of customers 3 Selects the customer 4 Displays products purcha-sed by this customer 5 Selects product to be serviced 6 Creates service record 7 Enters problem descr. 8 Stores problem description 9 Creates customer instructions 10 Sends e-mail to customer Software Systems Design - 4