Introduction - Ubiquitous Positioning - page 14

of the context within which any computer applications are being used. Of all the
contexts, the most fundamental are the identity of the subject, the temporal context
(when events occur), and spatial context of position (where everything is located
and its orientation) (see Figure 1.2).
Figure 1.2 The fundamental contexts of who/what, where, and when.
1.4.8 User Profile
An important issue relating to user context is that of the preferences of the user;
for example, whether the context of position is to be shared with any third party.
Usually preferences are contained within a personal profile that can either be
created manually or inferred. The profile can be used at both the server side and
the user side of any session, but generally, it is hosted and backed up at a server
operated by a service provider. Security and trust (arguably the most fundamental
services being provided in any on-line session) are managed by reference to the
profile and it is important to note that the inclusion of a Whereness context can
greatly facilitate their management. Whereness context can thus be useful in two
ways. First, it can be used to increase security and trust generally and second, to
support specific LBS applications. Presence is another important issue handled by
on-line services. It includes information such as “out at lunch.” Although
currently manually controlled, a Whereness service could perhaps automate many
presence services.