Wireless Middleware
Jim Geier is the author of Wireless LANs: Implementing Interoperable Networks(1999, Macmillan Technical Publishing).
As companies implement wireless networks, care must be taken to ensure that effective mechanisms are in place to effectively handle applications that operate over the wireless LAN. Many of the traditional techniques, such as terminal emulation and direct database connectivity using TCP/IP, are inefficient when deployed across a wireless LAN. To maximize performance and supportability of a wireless LAN application, consider the use of wireless middleware.
The following are common features of middleware products:
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Optimization techniques—Many middleware products include data compression at the transport layer to help minimize the number of bits sent over the wireless link. Some implementations of middleware use header compression, in which mechanisms replace traditional packet headers with a much shorter bit sequence before transmission.
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Intelligent restarts—With wireless networks, a transmission may be cut at midstream due to interference or operation in fringe areas. An intelligent restart is a recovery mechanism that detects when a transmission has been cut. When the connection is reestablished, the middleware resumes transmission from the break point instead of at the beginning of the transmission.
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Data bundling—Some middleware is capable of combining (bundling) smaller data packets into a single large packet for transmission over the wireless network. This is especially beneficial to help lower transmission service costs of wireless WANs. Because most wireless data services charge users by the packet, data bundling will result in a lower aggregate cost.
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Store-and-forward messaging—Middleware often performs message queuing to ensure message delivery to users who may become disconnected from the network for a period of time. When the station comes back online, the middleware sends the stored messages to the station.
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Screen scraping and reshaping—The development environment of some middleware products enables the developer to use visual tools to "scrape" and "reshape" portions of existing application screens to more effectively fit within the smaller display of data collectors.
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Support for mobile IP—Some middleware products offer home and foreign agent functions to support the use of mobile IP protocols.
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Operational support mechanisms—Some middleware products offer utilities and tools to monitor the performance of wireless end-user devices, enabling MIS personnel to better troubleshoot problems.
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Application-development tools—Some middleware packages also include application-development tools.
Many companies offer wireless middleware products. The selection of a preferred vendor depends on wireless network requirements, such as end-user devices and end systems.
About the Author
Jim Geier provides consulting services related to wireless networking to companies worldwide. He is the author of the book Wireless LANs: Implementing Interoperable Networks (Macmillan Technical Publishing, 1999). His "Online Guide to Wireless Networking" is located at http://www.wireless-nets.com/guide.htm.