Context-Aware Applications - Guide to Cloud Computing for Business and Technology Managers - page 512

ontology. For instance, the private ontology of an artifact that represents a
car contains a full description of the different components in a car as well as
their types and their relations.
The basic goal of the proposed ontology-based context model is to support
a context management process, based on a set of rules that determine the way
in which a decision is made and are applied to existing knowledge repre-
sented by this ontology. The rules that can be applied during such a process
belong to the following categories: rules for an artifact's state assessment that
define the artifact's state based on its low- and high-level contexts, rules for
local decisions that exploit an artifact's knowledge only in order to decide the
artifact's reaction (like the request or the provision of a service), and finally
rules for global decisions that take into account various artifacts' states and
their possible reactions in order to preserve a global state defined by the user.
23.3.2 Context Support for User Interaction
The ontology-based context model that we propose empowers users to
compose their own personal mobile applications. In order to compose their
applications, they first have to select the artifacts that will participate and
establish their associations. They set their own preferences by associating
artifacts, denoting the sources of context that artifacts can exploit, and defin-
ing the interpretation of this context through rules in order to enable various
services. As the context acquisition process is decoupled from the context
management process, users are able to create their own mobile applications
avoiding the problems emerging from the adaptation and customization of
applications like disorientation and system failures.
The goal of context in computing environments is to improve interac-
tion between users and applications. This can be achieved by exploiting
context, which works like implicit commands and enables applications
to react to users or surroundings without the users' explicit commands.
Context can also be used to interpret explicit acts, making interaction much
more efficient. Thus, context-aware computing completely redefines the
basic notions of interface and interaction. In this section, we present how
our ontology-based context model enables the use of context in order to
assist human-computer interaction in mobile applications and to achieve
the selection of the appropriate interaction technique. Mobile systems have
to provide multimodal interfaces so that users can select the most suit-
able technique based on their context. The ontology-based context model
that we presented in the previous section captures the various interfaces
provided by the application's artifacts in order to support and enable such
selections. Similarly, the context can determine the most appropriate inter-
face when a service is enabled. Ubiquitous and mobile interfaces must be
proactive in anticipating needs, while at the same time working as a spatial
and contextual filter for information so that the user is not inundated with
requests for attention.