Information Technology Reference
In-Depth Information
of the viewpoint specifications described so far, and are overlooked by most
specification approaches. Thus, they end up being incorporated very late in
the development process of the system. This is normally too late, when almost
no significant changes to the system specifications can be tolerated.
A second concern that is often ignored when preparing the specifications
of a large system is the need for establishing different conformance and com-
pliance criteria and tests. Conformance tests are those which check that the
components, languages and protocols used by an implementation conform
to the specifications and the standards listed in them as mandatory for the
system. For example, we may need to check that system services are im-
plemented as web services whose interfaces are described using WSDL and
which communicate using REST protocols, or that our operating systems are
ISO/IEC/IEEE 9945 POSIX conformant. Conformance tests are specified in
ODP using conformance points, where it is possible to check that the real
implementation matches the specification. Compliance tests are of a different
nature. They are concerned with checking that the system specification is
consistent with the architecture or design framework being used. Chapter 8
deals in more detail with these two kinds of tests.
Finally, any system specification should also include some plans for the
technology selection processes and for the evolution of the system parts (that
is, the software and hardware products that together comprise the system im-
plementation). We are all aware that current technologies change rapidly, and
therefore the kinds of changes foreseen and how to cope with them need to be
explicitly described and documented somewhere in the system specifications.
The developers of the RM-ODP introduced a dedicated viewpoint to ad-
dress these issues, namely the technology viewpoint, which is concerned with
all aspects related to the choice of technology to implement the ODP system.
6.2
The Elements of the Technology Language
The main goals of the technology language are to provide concepts and con-
structs to specify the hardware and software products from which the system
is built, to test that such an implementation complies with the specification as
prescribed by the rest of the viewpoints and to specify the plans and processes
for the selection, acquisition and evolution of the system parts (hardware and
software products) during its lifetime. The technology language defines four
main concepts: technology objects, implementable standards, implementation
and IXIT (Implementation eXtra Information for Testing | a name derived
from the earlier protocol specific OSI concept of a PIXIT).
