Information Technology Reference
In-Depth Information
8.2
A Conformance Community
The idea of conformance can be applied very broadly in many different ar-
eas, from product manufacturing through service provision through to the ap-
plication of management guidelines. ISO work on conformity assessment [19]
aims to be suciently general to cover this entire range, but for our pur-
poses we want a more specific framework, concentrating on open distributed
systems.
Part 2 of the RM-ODP provides a conformance architecture, which you
can think of as an enterprise model of the design, implementation and testing
activity (see figure 8.2); it defines three main roles, identifying the specifier,
the implementer and the tester. As usual, an object can fulfil more than one
of these roles, but it is simpler to describe the case where the roles are distinct
| the so-called third-party testing scenario.
The specifier produces and publishes a specification. Not only does this
specification say what an implementation should do, but it also constrains
how the implementation can be tested by defining where its behaviour can be
observed. This is necessary because many different styles of specifications can
represent the same intended object, and the implementer should be left with
as much freedom as possible to produce something that works eciently.
For example, a business process might describe the packing and dispatch
of a repaired phone as involving a sequence of steps: wrap the phone, print
a test report, print a label on the box, fill the box, perform a final check and
seal the box. It may or may not matter exactly in what order these happen. If
the specifier is just using the sequence for simplicity of description, but would
accept other sequential or parallel behaviour as doing the same job, we don't
want to be unduly restrictive.
However, for assessing some of these activities, such as the final check, it
may really matter that all the earlier steps have been completed. In this case,
the specifier declares the interaction between the checker and the previous
steps as a reference point . This means that it is a place where correct
behaviour may potentially need to be observed.
UML4ODP provides a simple profile that allows elements in the specifi-
cation to be stereotyped as
«
ODP ReferencePoint
»
and qualified by suitable
comments stereotyped as
«
ODP ConformanceStatement
»
.
A specification will generally be intended for reuse; the final decision about
what needs to be tested may vary when it is reused. A specification may
therefore identify quite a lot of reference points, indicating where testing is
possible, and the final integration of the full product specification will then
involve selecting a subset of these as conformance points, where it is stated
that final product testing is required.
The implementers obviously have to produce an implementation that
behaves according to the specification, and this involves them in making im-
