Early attempts at wireless computing used Transmission Control Protocol/Internet Protocol (TCP/IP) directly over wireless data services to offer common applications such as e-mail. The slow speeds and lengthy delays associated with wireless data transfer prevent this solution from working very effectively. Yet, this approach may still be viable for faster, reliable wireless data services. Consequently, several alternatives emerged. Among these were

• Custom data transport protocols, tuned for operation over a wireless data link or network

• Customized implementations of Transmission Control Protocol (TCP), tweaked to improve operation over wireless IP

• Middleware that insulates applications from wireless network characteristics

The custom alternative has been evaluated for several years without much success. Mobile IP addresses only part of the problem enabling mobility of IP addresses. Myriad options and Internet proposals attempting to define custom transports have not yielded a standard. The enormous embedded base represented by TCP simply overwhelms the marketability of transport protocols engineered specifically for wireless.

Companies have implemented the second choice (custom tuning of TCP) with some success. End users cannot tune standard off-the-shelf TCP implementations to completely address the issues surrounding effective transmission over wireless. Custom TCP services require tuning at both ends for this to work. This requires some due diligence on the part of users.

The third choice, wireless network middleware, addresses this concern by constraining wireless adaptation to a (smaller) set of devices, known as proxies. Wireless clients interact with proxies using a middleware protocol,...