Wizard API updated!
Tim Boudreau has released a new version of the Swing Wizard library (version 0.997) that fixes the WizardException bug reported in JavaWorld's recent Open Source Java Project profile. The article's examples have been reworked to test out the new, improved WizardException. Thanks, Tim, for this helpful fix!
Open Source Java Projects: The Wizard API

Newsletter sign-up

Sign up for our technology specific newsletters.

Enterprise Java
View all newsletters
Email Address:
JavaWorld.com > Java Enterprise Edition >

Build database-powered mobile applications on the Java platform

Use JavaServer Pages as a gateway between MIDP applications and databases

By Michael J. Yuan and Ju Long, JavaWorld.com, 01/18/02

Internet-connected mobile devices are important tools in our daily lives. The ability to access information in realtime and in real-life circumstances has enabled us to work more efficiently. To fully harness mobile commerce's potential, we need to integrate wireless devices with the rest of the Internet. In particular, wireless devices should be able to access the vast amounts of data on Internet backend databases and utilize data processing power from enterprise-level database applications.

To achieve that functionality, Java is our best bet. It offers the ideal platform for developing complex mobile commerce applications. Java programs can deploy on both the wireless device and the application server, independent of host hardware and operation systems. Client-side and server-side Java applications can integrate seamlessly under consistent API designs.

In this article, we explore ways to access Internet backend databases from Java-enabled mobile devices. We use a simplified example to illustrate our approach and explain the design and implementation decisions we made.

The Java platform for small mobile devices

The standard Java APIs and virtual machine (VM) are feature rich. But standard Java applications are simply too big and too slow to run directly on resource-constrained mobile devices. Small runtime memory footprint and fast execution speed prove essential for mobile commerce developers. In response to this need, Sun created a small-footprint edition of Java: J2ME (Java 2 Platform, Micro Edition).

J2ME is divided into configurations and profiles. You can use different combinations for different memory and processing power requirements. The Connected Limited Device Configuration (CLDC) and Mobile Information Device Profile (MIDP) combination is designed specially for resource-constrained mobile devices, such as wireless phones and personal digital assistants. CLDC provides class libraries to support a limited set of Java core language APIs; MIDP provides device-specific implementations for application-level APIs, such as GUI components, network connection, and persistent storage. CLDC and MIDP work together to provide a complete development and runtime environment for mobile devices. Each MIDP-supported mobile device has a MIDP VM that can run compiled MIDP byte code. Thus, MIDP applications run on all MIDP devices.

Unlike applications built around browser-based technologies such as WML (Wireless Markup Language) and other HTML variants, MIDP applications are real programs that can handle interactive user interfaces, manipulate data, and allow offline user interaction. In contrast with platform-native applications, MIDP applications are portable across all mobile platforms and can deploy over the Internet. MIDP developers can take advantage of Java's sound object-oriented design and the many third-party libraries/components available for the Java platform.

A MIDP application's basic component is the MIDlet. A MIDlet can have its own event handlers and user interface. Several MIDlets and their supporting classes work together in a MIDlet suite to provide a MIDP application's complete functionalities (for more information about MIDP development, see Resources). However, MIDP lacks a crucial functionality for database-powered applications: Java Database Connectivity (JDBC). In the next section, we discuss how to access databases from MIDP applications.

1 | 2 | 3 |  Next >
Resources