B2B Integration : A Practical Guide to Collaborative E-commerce

Wireless Technologies 349
Many middleware products possess features that go beyond the basic
functionality of connecting appliances to applications and databases
located on the wired network. The important features of wireless network
middleware are:
Optimization Techniques — Middleware often includes data compression
at the transport layer to help minimize the number of bits sent over the
wireless link. A variety of compression algorithms are employed to
perform the compression, including V.42bis, Hoffman encoding, runlength
encoding and proprietary compression techniques. Some
middleware use header compression.
Intelligent Restarts — Unfortunately, with wireless networks a
transmission may be disrupted due to interference or operational
problems. A recovery mechanism often employed is an intelligent restart
that detects when a transmission has been cut and when the connection
is reestablished. With intelligent restart, the middleware resumes
transmission from the breakpoint, instead of at the beginning of the
transmission.
Store-and-Forward Messaging — In order to ensure message delivery
to users who may become disconnected from the network for a period
of time, middleware performs message queuing. Once the station comes
back online, the middleware will send the stored messages to the
station.
Screen Scraping and Reshaping — Many middleware products have a
development environment that enables a developer to use visual tools to
'scrape' and 'crop' portions of existing application screens to fit within
the smaller display of data collectors.
Operational Support Mechanisms — Some middleware products monitor
the performance of handheld devices through utilities and tools, which
enable IT personnel to better troubleshoot problems.
Middleware connectivity often possesses the following attributes:
Highly efficient operation over wireless networks — Middleware reduces
the load on the wireless network through the use of optimization
techniques, such as data compression and screen scraping.