Question 1 (20 marks)

What are the differences and similarities between a low-end internet device such as a MIDP mobile phone and a high-end desktop PC?

Question 2 (20 marks)

A home heating system has methods to

• Set the temperature from a start-time to a stop-time for a day of the week.
• Override the current temperature to a new value (e.g. to make it warmer).
• Reset the temperature to the preset temperature

Write a Java interface for the heating system. Pay particular attention to exceptions, such as setting temperatures for overlapping times.

Question 3 (20 marks)

An electronic photo album (of the future) can store digital photos for long term storage. A data display can display images from a device. A camera can take digital photos. If these all have network connections, they can be regarded as internet devices.

Suppose all three devices are available as services (or clients) on a network. What messages can be sent between the three to take, store and display photos? Draw diagrams to show the devices and the messages between them.

Question 4 (20 marks)

Following on from Question 3, suppose the camera "knows" the data display and the photo album. The camera has a set of pictures it has taken and stored locally. Each photo is of class

    public class Photo {
        public String name;
        public byte[] data;
    }

The camera has enough processing power and has a display which allows it to run a MIDP user interface. Write MIDP code to run on the camera which will:

• Display the set of photo names;
• When a photo is selected, list the other devices (display, album);
• When one of these devices is chosen, call an appropriate method on the device, with suitable arguments, to either display or store the photo.

Question 5 (20 marks)

An internet burglar alarm system can be queried to see if it is running and secure, and it can also generate alarms when security is breached. The local Police Station keeps a list of burglar alarm services and regularly queries their status. It also receives and acts on alarm calls.

Using ordinary Java objects and RMI proxy objects, show the Java objects and methods needed to implement such a system on the alarm and Police Station. Do this using UML diagrams or Java classes, showing attributes and method signatures. Do not write any method implementations.

Question 6 (20 marks)

A home has an 80cm TV with digital theatre surround sound in the loungeroom, a smaller 48cm TV in the bedroom, and a portable black-and-white 30cm TV. Which properties belong to the TV as a service, and which are additional attributes? Illustrate using a Java interface for the service, and Jini Entry objects for the additional attributes.