1. TK2023 Object-Oriented Software Engineering CHAPTER 3 CASE STUDY: POS SYSTEM

2. POINT-OF-SALE (POS) SYSTEM A POS system is a computerized application used to record sales and handle payments; it is typically used in a retail store. It includes  hardware components such as a computer and bar code scanner  software to run the system It interfaces to various service applications such as a third-party tax calculator and inventory control.

3. It must be relatively fault-tolerant. It must support multiple and varied client-side terminals and interfaces. It must be flexible and customizable. For example, it should be able to be customized for a different client.

4. FOCUS OF CASE STUDY User Interface SalePayment Logging...Database Access... application logic layer technical services layer minor focus explore how to connect to other layers primary focus of case studies explore how to design objects secondary focus

5. Application Logic and Domain Object Layer  consists of software objects representing domain concepts that fulfill application requirements Technical Services Layer  consists of general purpose objects and subsystems that provide supporting technical services. These services are usually application- independent and reusable across several systems.

6. Object-oriented analysis and design is generally most relevant for modelling the application logic and technical service layers. Emphasis will be placed on the problem domain objects and allocating responsibilities to them to fullfill the requirements of the application.