gestão de dados partilhados em ambientes de computação móvel

Abstract
The widespread use of mobile devices and wireless communications has created a new distributed com-
puting environment, usually called mobile computing environment. Computing systems, including data
management systems, must be adapted to address the new and intrinsic characteristics of these environ-
ments.
This dissertation studies data management for mobile computing, and, in particular, the problems
involved in data sharing. To address these problems, we propose the extensive use of semantic informa-
tion.
This dissertation also identifies a set of principles that explore the available semantic information to
allow multiple users to share data in a mobile computing environment. We divide these principles into
two groups. The first group aims at providing near-permanent read and write data availability in the
presence of any connectivity conditions relying on: optimistic replication; partial caching; and opera-
tion during cache misses – blind invocation. The second group deals with concurrent operation relying
on: conflict avoidance; log propagation and situation-specific reconciliation; and handling of awareness
information.
These principles were developed and validated during the design, implementation and evaluation
of two data management systems for mobile computing with different characteristics. DOORS is an
object repository designed to simplify the development of new asynchronous groupware applications.
Mobisnap is a relational database system designed to support typical database applications in a mobile
computing environment.
The principles identified in this dissertation were applied, in each system, using different data ma-
nagement techniques that explore the available semantic information. These specific techniques are also
presented in this dissertation.
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