Mobile Wireless
Mobile wireless middleware

The major role of wireless middleware is bridging enterprise applications that are running on wired networks with WLAN and mobile WAN transports. Middleware can take the form of a gateway or a software development tool, or it can be included in the offerings of a wireless application service provider. Figure shows a Wireless Application Protocol (WAP) middleware example. The Wireless Markup Language (WML) is a language similar to HTML, which has been optimized for wireless. It is based on the Extensible Markup Language (XML). WAP is covered in the next section.

There are different approaches to accomplishing this bridging role, and different functions that can be provided by the various solutions. Not all vendor products will perform all of the functions. Some of these functions include the following:

  • Data and header compression – Compressing data minimizes the payload sent over wireless links, which boosts bandwidth efficiency. This can be particularly important to user response times.
  • Recovery from breaks in transmissions – Transmission interruptions are caused by poor coverage or interference. Some middleware can detect when a transmission has been interrupted. The middleware will enable the session to resume from the breakoff point when the session is reestablished. Some middleware will queue messages, to protect users who may become disconnected from the network. Then, when the user reconnects, the messages will be forwarded to the mobile device of that user.
  • Packet consolidation – Some middleware will combine smaller data packets into a single, larger packet for transmission over the wireless network. This can help lower transmission service costs of usage-based mobile WAN services that charge users by the packet.

The Cisco CTE 1400 Series Content Transformation Engine is another middleware solution. The CTE 1400 transforms existing enterprise content for display and interaction on small-screen mobile devices and IP phones. When a device makes a connection request, the CTE transforms the content to suit the device, using a transformation rule as shown in Figure . The source data is left unchanged.