Information Technology Reference
In-Depth Information
Behaviour
required
from user
Needs of
the user's
application
Capabilities
of the COTS
component
FIGURE 12.2: Broadest and narrowest behaviour envisaged by the supplier
and the behaviour needed by the user.
shows the behaviour the user is obliged to initiate and the outer contour shows
behaviour the user is permitted to initiate.
The user will also have a model of what the product is to do for them.
Again, this is a subset of the actual capabilities of the product, this time
indicating what subset of the features available is actually to be used (see
the middle contour in figure 12.2). It may also indicate whether particular
features are essential to the user's business processes or are merely desirable.
Of course, the supplier may not make the product models available in
a form suitable for assessment, or in extreme cases may only describe the
product in the broadest marketing terms. In such cases, the potential customer
will need to construct their own description of the product, filled in where
necessary by asking the potential supplier questions.
The provision by the supplier of a rigorous model showing what they claim
their product does is also important in considering conformance. Once the
supplier has claimed that a given model represents what their product does,
the user can apply it both as a conformance target, checking test observations
against it, and in the validation of their own designs, to check that the services
they are building on top of the component will match their business needs.
The above discussion gives an idealized and simplified sketch. For example,
each of the models described may be manifest in more than one viewpoint.
Using viewpoints will help to organize the required assessments, but there may
be differences in interpretation in the various supplier and user organizations,
reflecting their own internal structures and stakeholder responsibilities.
To position this information in the ODP framework, the product and user
models discussed previously will, in general, need to be restructured to create
the necessary sets of viewpoint models. We can consider the key features of
these for each viewpoint in turn. Firstly, this process will have little impact
on the enterprise viewpoint because most products will be generic from the
user's point of view. The product's information viewpoint will need to be
related to the broader user model by establishing a series of correspondences,
mostly in the form of subtyping relationships from general supplier definitions
to specific user ones. The computational model describing the intended uses of
the product will be a subset of the computational model for the application as
a whole, and the user technology model of support provided will be a superset
