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CONTEXT MANAGEMENT
FRAMEWORK
and space rather than the inherent characteristics
of the entity itself.”
The second indicates that “context is always
related to a focus and that, at a given focus, the
context is the aggregation of three types of knowl-
edge: Contextual Knowledge (CK), External
Knowledge (EK) and Proceduralized Context
(PC)” (Viera et al. 2008). They argue that context
should always be considered related to a focus,
which is a step in a task execution, in a problem
solving or in a decision making process. Moreover,
the context evolves dynamically according to the
focus, which enables a context-aware system to
separate relevant from not relevant knowledge in
order to determine the context.
Figure 1 illustrates the proposed working defi-
nition of the context (Jaroucheh et al. Feb 2010).
The term context primitive (for short, we will refer
to it as CP) refers to a piece of contextual knowl-
edge such as entity, entity attribute, relationship
between two entities, their constraints, or inference
rules -used to define context situations and infer
new knowledge- that can be used to define the
context. We consider that the context knowledge
is composed of a set of small pieces. Given a
focus, a relevant subset of these pieces, namely
context primitives, will be used to generate the
current context. Thus, the generated context is in
alignment with the requirement of current task.
Context-Aware Systems
Context-aware applications are those that con-
sider the current situation of their users in order
to provide services and information tailored to
their needs. An important topic when dealing
with context-aware systems is how to model,
manage, and manipulate the context information.
To ease context representation, context sharing
and semantic interoperability between hetero-
geneous systems, a formal and generic context
model is needed (Gu et al. 2005). In this work,
we are interested in developing a context-aware
application development methodology (Software
Engineering perspective); and in particular we
are focusing on context modeling (Knowledge
Engineering perspective).
In the literature, there are many definitions
for context. Definitions given by earlier works
agree on the key idea that contexts describe situ-
ations. For example (Dey 2001) confirmed this
by defining context as: “Any information that can
be used to characterize the situation of an entity.
An entity is a person, a place, or a physical or
computational object that is considered relevant to
the interaction between a user and an application,
including the user and application themselves.”
This work is based on two other definitions of
context. The first states that in using open-ended
phrases such “any information” and “character-
ize” the context becomes so broad that it covers
everything (Winograd 2001). Winograd indicated
also that “something is context because of the way
it is used in interpretation, not due to its inherent
properties. The voltage on the power lines is a
context if there is some action by the user and/or
computer whose interpretation is dependent on
it, but otherwise is just part of the environment.”
In this work, we adopt his definition of context:
“context depends on the interpretation of the op-
erations involved on an entity at a particular time
The Variability in Context
Information
Several middlewares and ontology-based models
for describing context information have been
developed in order to support context-aware
applications. However, the context variability,
which refers to the possibility to infer or inter-
pret different context information from different
perspectives, has been neglected in the existing
context modeling approaches.
In order of the context management infra-
structure to serve different types of applications,
it should provide context-specific programming
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