luetooth is one of today's most exciting technologies. It is a short-range radio wave wireless technology operating in the 2.4 GHz frequency spectrum. With an operating range of 30 feet (10 meters) and a maximum transmission rate of a mere 1Mbps, Bluetooth is widely touted as the "cable replacement" solution.

Bluetooth has been around for awhile but there seem to be few developers who have experience in building applications that will run over Bluetooth. In this article, I will show how you can build a Bluetooth chat application using the .NET Compact Framework. Once you've built a chat application using this simple example, you should have a good foundation for building any number of killer Bluetooth applications.

The chat application enables two users with Bluetooth-enabled Pocket PCs to communicate with each other so long as they are within the 30-foot range of Bluetooth. It is useful as a communication tool during meetings, where private conversations can take place without affecting the meeting or as a mobile substitute for instant messenger.

What You Need

Visual Studio .NET 2003 Final Beta (available now to MSDN subscribers) Two Pocket PCs with Bluetooth capabilities. (Most new Pocket PCs today ship with Bluetooth capability. For Pocket PCs without built-in Bluetooth, you can purchase Bluetooth expansion jackets/cards from the respective vendors.) Microsoft ActiveSync 3.6

	Figure 1: Two Pocket PCs. To build and test the chat application I used two Pocket PC devices from Compaq: an iPaq 3870 (with Bluetooth built-in) and an iPaq 3630 (with the Bluetooth Expansion Pack for the iPaq 3630).

The Pocket PCs I used in preparing this article are shown in Figure 1.