Australian Education Union HendroNindito
Case Study : AEU The Australian Education Union (AEU) keeps the records of its properties and activities in a database using an object-oriented concept. Property can be divided into two main categories: building and vehicle. Beside these two, there are also other minor properties that are not categorized into building and vehicle. Each building has several rooms and each room has computers in it. Some of the rooms also have overhead projectors (OHPs).
Case Study : AEU ( cont…) The union employees’ records are kept in a separate class. Employees can be divided into two types: office staff and organizers. Management is not included in these two categories, although their data is also kept in the employee class. While office staff work only internally in the union, the organizers have to represent teachers in the area to which they have been assigned. One organizer can represent many teachers, but one teacher can have only one organizer as her or his representation. For this purpose, each organizer has been given one vehicle, and that vehicle may be used only by that particular organizer. Each organizer will be assigned only one area, which can be divided into several suburbs. The area and suburb data are also kept in separate classes.
Case Study : AEU ( cont…) The union also keeps records for teachers who are union members. All of these teachers have to work in government schools. Although it is not common, a teacher can work in more than one school. The type of school that can liaise with AEU has to be categorized into one of the three distinct types: primary school, secondary school, and technical college (TechC).
Solution • Identify Objects To start with, we know that there will be a union object to store the data about the AEU organization. It also has a property object that can be divided into building and vehicle objects. Furthermore, there is a room object that is composed of PC and OHP objects.
Solution (cont…) Next, we will need an employee object for AEU’s employee records. Their types are also objects: Office Staff and Organizer. For working area and suburb, we need two new objects as well.
Solution (cont…) Finally, as employees will need to work with teachers, we need a teacher object. Along with that, the additional objects of School and its specializations— Primary, Secondary, and TechC—will be added.
Solution (cont…) • Identify Relationships There will be three types of relationships that we need to recognize before producing the object-oriented model diagram.
Solution (cont…) First, we need to identify inheritance relationships. Inheritance can be shown by the generalization specialization feature. One of them is between Employee and its specializations Office Staff and Organizer. Property can also be specialized into Vehicle and Building. And the last one is the specialization of School into Primary, Secondary, and TechC.
Solution (cont…) Second, we need to identify association relationships. This relation is usually the most frequent relation in an object-relational system. From the union object there are two associations: one to Property (one to many) and the other one to Employee (one to many).