Integrated Networks for Seamless and Transparent Service Discovery

NOMAD Client for J2ME

The user interface implementation follows the specifications from the Deliverable D2.4.

The GUI classes display an interactive user interface and wait for user input. When the user generates an UI event by pressing a button or selecting an item from the list, the view’s class event handler captures the event and passes the control to the midlet class on the business logic layer.

The implementation of the GUI uses the UI libraries provided by the MIDP1.0, taking into consideration the portability across the devices. The portability is achieved by using high-level MIDP APIs, provided through the screen classes, such as: List, Alert, and Form.

Users interact on a screen-by-screen basis with their applications.

All screens are part of LCDUI, the user-interface components of MIDP. The package was designed for devices with small screens and limited or absent windowing capability.

There are two categories of LCDUI screens: structured and unstructured. Structured screens are more portable, but do not give the application access to low-level input mechanisms or control of the screen. Unstructured screens provide access to low-level I/O, but can be less portable.

Structured screens are created using the LCDUI high-level APIs, which provide user-interface components such as lists and forms.

High-level screen components are designed to make MIDlets portable across devices. In addition to visual appearance, the MIDP implementation handles navigation, scrolling, and other primitive interactions. MIDlets are portable because they are not aware of these low-level, device-dependant tasks.

Screen images

The user interface was designed with the aim to assure an easy navigation from one screen to another and to offer an easy way for the user to enter his commands.

The user interface of the J2ME phone client has 4 components (screens):

• The main screen is the NomadClientScreen class, a form displayable, from which the main program commands are available (Query Services, get Position, etc). In this screen there will be also displayed the position data (map or coordinates).
• PropConfigScreen – is a configuration screen, where the user can choose the appropriate configuration data
• NomadListScreen – is a list screen, which displays a list of the available services
• NomadResScreen – is a form which displays the results of the “Service Detail” or “Show Map” actions

By launching of the nomad phone client program, the following screen will appear:

Figure 1: Nomad main screen - Emulator image

From this screen there are more navigation options and results, as shown in the following images.

Figure 2: Indication of the current position

Figure 3: Service discovery

Figure 4: Configuration screen