Software development for enterprise systems
Software development for enterprise systems

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Software development for enterprise systems

6.3 Networks of objects

No serious program consists of a single object. Instead there will be a network of objects, which collaborate to achieve the functionality of the whole system. Figure 4 shows a network of objects representing a hotel, some guests and some rooms. This sort of diagram is called an object diagram or a snapshot diagram. It shows one particular possible configuration of the system. This particular diagram shows the state of the system when it contains a single hotel, two guests and two rooms. The guest with name ‘Jack’ is linked to the room with name ‘blue suite’, and the guest with name ‘Jill’ is linked to the room with name ‘r234’.

Figure 4
Figure 4 A network of objects

The notation used in Figure 4 is the UML notation for object diagrams. Each box represents an object and the data it encapsulates, and that objects can be linked to other objects.

A link is a connection between two objects that is significant for the application area. To establish a connection between two objects we need to identify, and distinguish between, each object. An identity is an unchanging property of an object that distinguishes it from all other objects. Software distinguishes between objects using an internal identity that is intelligible only to the software system; objects are not distinguished by the data they store.

How people distinguish between real-world objects is different from how software distinguishes between objects which may represent those real-world objects. People distinguish between real-world objects using identifiers with values that are understood by other people, e.g. a property such as a person's name. This conflict of identities has to be resolved by the interface between a system and its users.

M885_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus