TABLE OF CONTENTS Mobile applications running on a mobile device typically connect to an enterprise system or an e-commerce system through a wireless application gateway. A wireless application gateway, as the term implies, is essentially the access server for mobile devices. When the underlying application is delivered to a mobile device via the web, a wireless application gateway will serve as a wireless web server dedicated to mobile browsers; otherwise, a wireless application gateway acts as a general-purpose back-end server for applications running mobile devices. Network connection between a wireless application gateway and a mobile client could be any kind of wireless networks such as cellular, wireless LAN, Bluetooth, and WiMax, whereas the wireless application gateway and back-end systems are often connected via a wired network.
The functional components of a wireless application gateway are depicted in Figure 7.20. On top of IP is the wireless transport support including datagram transport layer functions, session management, and transaction support. Depending on the purpose of a wireless application gateway, certain business logic pertaining to CRM or ERP, location-based mobility support such as customer search in a geographic area, or end-user profile support can be realized based on wireless transport support. Security mechanisms must be provided along with these supporting functional components as well as with wireless transport layer implementation. Server process output, usually in the form of a markup language such as HTML, WML (in earlier WAP), xHTML (in WAP), or cHTML (in iMode), must be...
