Integrated Networks for Seamless and Transparent Service Discovery

NOMAD Client for PDAs and Laptops

The UI presents to the user all the functionality to take full advantage of the NOMAD Service Discovery platform. It is simple and self explanatory. The Look and Feel is of high quality and works identically for Laptops and PDAs.

UI events are generated by each user selection of items on the result list or tree views. The commands are in the form of buttons. Animated images inform the user for actions in progress.

The basic problem to overcome was that the Java VM on the PDA was a version 1.1.8 implementation compatible and did not support Swing. The solution was a library from Thinlet that is based on AWT and has all the necessary widgets for the UI. Some functionality had to be added though, to improve the editing of the user preferences.

Screen Images

The UI is shown in the following figures. It presents the user three pages selectable through tabs. The user's location is shown in the status line which is visible continuously. The pages are:

• The Services page
• The Preferences page
• The Results page

Figure 1: NOMAD client main screen - Services page

Figure 2: Preferences and Results pages

The Services page

At the bottom of the Services page there is a button labelled "Query Services", used to fill the Services' List at the top of the page. After a successful query, the user can select an item from the list and this action automatically changes the display to the Preferences page.

Figure 3: Service discovery

The Preferences page

The Preferences page consists of a table that is filled with attributes of the selected service and at the bottom a button labelled "Get results", a spinbox and a combobox. When there are more than one service component present the user can select this component through another combobox that appears at the top of the page. The figures below show some snapshots of the Preferences page filled with data.

Figure 4: Selection of an individual service component

Figure 5: Selection of an individual service component

Selecting a different service component changes the contents of the preferences table. This table consists of two columns: the "Option" column and the "Requirement" column. The first contains the name of the attributes of the service while the second contains preferred values. The entries of this column can be edited according to the user's preferences or left empty. Previous values are remembered by the software and automatically inserted when the table is filled. Each cell, when selected for editing pops up an appropriate editor which is a text editor for text values, a spinbox for numerical values or a combobox for enumerated values. This is shown in the following figures. The icons in each cell imply the type of values required.

Figure 6: Popup editors for enumerated and numerical values

The spinbox and the combobox at the bottom of the Preferences page are used to define the geographical range inside which the user requires the results to be valid. As shown in the following figure, the user can select a spatial unit of 100m, 1Km or 10Km through the combobox and then a multiplier of this unit through the spinbox. A zero on the spinbox disables the geographical restriction of the query. Finally the user queries for the results by clicking the "Get results" button. After a successful query the display changes automatically to the Results page.

Figure 7: Selection of the range for the query

The Results page

The Results page consists of split pane and the "Select" button. The split pane contains a tree view of the results and a list of the attributes of each entry in the results' tree. The user can navigate through the results by selecting an entry in the tree. When satisfied by an entry the user may press the "Select" button to minimise the solution and reach at a single solution recursively.

Figure 8: Navigation through results