Advertisement

Summary
The ServiceUI specification developed by the Jini.org community defines a suggested procedure for attaching user interfaces to Jini services. In this article, Jeffrey Peden introduces you to a simple ServiceUI-based example service. Then he shows you how to build an application for browsing and launching user interfaces for Jini services.

In October 1999, Bill Venners first introduced readers to a working draft of the ServiceUI specification for attaching user interfaces to Jini services. In the year and a half since then, the ServiceUI project at Jini.org, largely due to Venners's efforts, has released a 1.0 specification and reference implementation.

In this article, I'll explain how to attach an interface to a simple Jini service, and then walk you through building an application to browse those services using Swing components and the ServiceUI framework.

Project Requirements

Before starting any development project, it's important to define what you're trying to build. If you're learning to program on your own, that may only consist of notes on scraps of paper. If you're a developer working within a team, however, that often entails rigorous documentation garnered from multiple whiteboard-intensive meetings. Here I'll briefly describe our goals for the project and the tasks ahead of us.

The Time Service

The Jini service Time is intended to demonstrate how to attach a graphical user interface (GUI) to a service. The service itself will be extremely simple: it's sole purpose is to provide a way to retrieve the current time and date.

The GUI attached to that service should provide a time display retrieved from the service, and a way for the user to update the display.

The Jini TaskBar

A Jini service with a user interface is useless if you have no way to view the UI. To that end, we'll design an application that can discover Jini services on the network and display associated UIs. While finding network services involves a certain amount of complexity, the application should try to hide that complexity from the user. Therefore, we'll model our application after one of the most common application browsing and launching systems: the TaskBar.