Information Technology Reference
In-Depth Information
but this is an area where much research is currently underway, and new pro-
posals are emerging [51, 68, 69].
2.9 Identifying the System's User Interfaces
The enterprise specification identifies the points at which users interact
with the supporting system. For example, figure 2.10 shows a process defini-
tion that contains interactions between the role Branch system and the roles
User, Branch staff, HQ system, Logistics Provider, and Phone Supplier. In this
diagram, at least the interactions between the User or Branch staff (roles that
are filled by human beings) and the Branch system (fulfilled by a computer
system) occur at a visible user interface. We will concentrate on these because
the other roles are not expressed in sucient detail in this figure to determine
whether the interactions are between humans and machine or machine and
machine.
The nature of the interactions can be expressed in many different ways, but
a common approach is one that divides the design activity into three separate
but related aspects (or, in our terminology, viewpoints), which are concerned
with content, navigation and presentation.
Content focuses on the persistent information handled by the system.
In hypermedia systems, the content viewpoint may include not only
raw data about the entities managed by a traditional system (orders,
customers or inventory items) but also more complex entities, such as
images, video clips, audio tracks and animations.
Navigation deals with how the content can be accessed; it covers which
content items can be visited and how a user can move from one to
another. Navigation thus establishes the possible paths that the user
can take through the content maintained by the system.
Presentation deals with the visualization of the content and of the
various interactive elements that support the functionality of the system.
These views can be mapped into the RM-ODP viewpoints in quite a nat-
ural way. In the enterprise viewpoint, we are concerned primarily with an
abstract view of navigation. The other aspects are dealt with in different
viewpoints. The content elements are precisely those represented in the infor-
mation viewpoint and the computational viewpoint will address how the broad
navigational flows are realized. Presentation is described in the engineering
viewpoint, where the presentation styles and templates are specied | at the
end of the day these elements belong to the same category as the message
