TheServerSide.com - Working with J2ME

TheServerSide.com - Working with J2ME:
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Introduction

This paper explores the various facets of building a J2ME application. It assumes a working knowledge of Java. The focus is on a MIDP 1.0/CLDC 1.0 application that depends heavily on network access.

I have been working with Java for the past four years, primarily in web application development. For the past year and a half, I have worked on a team developing a J2ME application; most of the information presented here has been gained in that experience.

The Problem

Imagine you are commuting in traffic. There is a long line of cars ahead of you on the interstate; there is a line at the next exit. It looks like a wait either way. Luckily, you subscribe to a traffic congestion service. If you use your cell phone to enter your location, the service can return high congestion areas close to you. Hitting the brakes in frustration, you enter the cross streets just ahead. The traffic service queries a database of current traffic in your city, and informs you that there is congestion on the cross street ahead, making the interstate a better choice. You turn up the radio and leave the other cars on the exit ramp behind.

This problem has some salient characteristics: users need information, and may not be in front of their computer. Data only needs to be queried, not entered, and does not require complex presentation. In addition, the immediacy of access is more important than depth of information.

Other characteristics of this type of problem include: users may be non technical, more than one remote system may be involved, and control over such systems may be distributed--there may be one or more traffic congestion reporting databases in a given city.

To sum up, the problem that this paper will examine is: what is the best way to allow real time, read only access, for remote, possibly non-technical users, to an information system, or set of systems. In this paper, I explain why cell phones clients are a good answer to this type of problem. In addition, I also show how Java 2 Micro Edition (J2ME) is a good platform for such a client. I also outline some of the design choices and technical issues faced when building a J2ME client to access a system like the traffic congestion service."