Information Technology Reference
In-Depth Information
Conversely, considering the means of transmission at high speed (e.g.
620Mbps or even 155Mbps examined earlier), the behaviour of the average
response time of the system is exactly the same as previously considered: the
fact of having a high speed transmission channel highlights the importance of
having a cache memory. In conclusion, for high-speed channels, the 'bottle-
neck' of the server node is given by the disk [7].
3
Context-awareness
We have focused our attention on issues that may make possible the
discovery of a service, citing the problem of detection of the users or the
knowledge of the environment by ubiquitous devices; all of this constitutes
the context, while the capability of the devices to interact in a certain manner
in a given situation, that is, of having a knowledge of the environment in
which they work, is named 'context-awareness'.
3.1
What is context-awareness?
The term
context
is used to denote a set of information characterizing the
state, the situation in which there is an entity, meaning as an entity a person,
an object or a place, which is taken into consideration [9-11]. If, for example,
a project for a tourist guide is considered, the context will be all information
regarding its position on what tourists want to visit, their personal preferences,
etc., so the context is not only a set of purely physical information, but personal
information, preferences, their knowledge and previous interactions with the
system, which can also be viewed as part of the context.
3.2
Possible applications
The theory on the understanding of the context opens the way for economic
development and the design of many projects [12,13] based on using hand-
held devices, their prototype should ideally be provided with a screen
allowing the user interface through special pens or just using fingers, or the
ability to access the physical memory devices, such as a CD, as well as to
remote resources via the Web, easy ways to communicate with other devices,
interface and video, or audio input and output, for instance, based on speech
recognition or cameras that enable it to interpret the gestures of a user or to
recognize objects and symbols of the surrounding environment. The applica-
tions of such devices [11,14,15] are manifold and behind them there is the
need that the system has knowledge of the context of the user.
