Databases Reference
In-Depth Information
proxy is added to the Web server. Finally, in WebExpress [13], there
are proxies in both parts, client and server.
Systems that provide an environment for the development of mobile
applications. For example, the Rover Toolkit is software that sup-
ports the construction of mobile-transparent and mobile-aware appli-
cations based on the idea of relocatable dynamic objects and queued
remote procedure call [14]. Also interesting is the work developed
by the DATAMAN group that has defined a set of classes, called
Mobjects, that would form the basis of a toolkit to implement appli-
cations for mobile computing devices [15].
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This chapter presents basic concepts and issues related to data management
for mobile computing. First, we present a motivation and the widely accepted
architecture. Then we explain briefly different wireless networks and introduce
the problems inherent to the framework and, specifically, the impact of mobile
computing in the area of data management. Finally, we explain the main fea-
tures of the more frequently used communication models and those related to
agent technology and describe some design characteristics.
10.2
Motivation
There is no doubt that mobile computing offers new computing opportuni-
ties to users. We present three scenarios in which the three main features of
the new paradigm are reflected: (1) access to distributed information reposi-
tories anywhere, anytime, (2) information delivery by broadcasting, and
(3) provision of user-tailored information.
The first scenario considers one day in the life of a salesperson
equipped with a personal computer. Our salesperson plans her work days in
advance, so before going to bed each night, she switches on her mobile com-
puter and asks if there are any new assignments. After reading the messages,
our salesperson adds the new tasks to her agenda and plans the following
days itinerary. The following morning, she leaves home to visit the first cli-
ent of the day. Before leaving, however, she uses her mobile computer to find
the best route to the clients office based on up-to-date traffic conditions. She
also requests the clients file. Our salesperson stops in a café before arriving at
the clients office, and while she has a coffee she reviews the most important
data related to the client to prepare for the interview. Once the interview has
been concluded, she enlarges the clients file, registering that days visit and
its results and sending the new data to her companys DB. During the rest of
