Information Technology Reference
In-Depth Information
enterprise framework. However, of late, these terms have been over-used and
now lack focus. In these terms, the RM-ODP is an architectural framework
for the design of any distributed system, particularly those whose complexity
poses a challenge.
The Reference Model was published in the mid 1990s, following almost 10
years of work in the International Standards Organization to harvest the best
architectural work up to that time. The results were published as common
text by both ISO and the ITU-T (the telecommunications standards forum).
The RM-ODP was published in four parts [2{5]. These four parts provide
an introduction, a set of rigorous basic concepts, the architectural framework,
and a link to supporting formal techniques. The users of this framework
are expected to be system designers, but it is also intended to help people
who build tools to support such design activity, or who produce standards to
capture best practice and reusable mechanisms in this area.
The RM-ODP defines a framework, but not a methodology. It gives the
designer a way of thinking about the system, and structuring its specification,
but does not constrain the order in which the design steps should be carried
out. There are many popular design processes, and the framework can be
used with practically any of them.
Since ODP system designs are typically large collaborative efforts, it is
likely that the actual process will be iterative, filling in detail in different parts
of the specification as ideas evolve and requirements are better understood.
However, the sequence in which this is done will depend on circumstances. In a
green field, design may follow a classical top-down, waterfall-style pattern. In a
legacy migration exercise, it will start by capturing existing constraints. In an
agile or rapid prototyping environment, design will stress modularization and
fine-grained iteration. The ideas for structuring specifications presented here
can be applied within any of these methodologies. They remain valid if the
design approach changes, and provide a common framework and vocabulary
for collaboration between designers using different processes.
Many competing architectural frameworks have recently been proposed,
and some of the better-known ones are reviewed in section 16.5. However,
ODP offers a set of distinguishing features that make it particularly relevant
for the specification of open distributed systems for enterprise and informa-
tion handling applications. First, it has the authority and stability that goes
with its status as an international standard. You can use it with the confi-
dence that it is controlled by proven international processes, and will not be
unilaterally changed by some individual group or private organization. Sec-
ond, it is based on a rigorously defined set of formal concepts, and so has a
precision that positions it in close alignment with the current software engi-
neering and model-driven trends within the industry. Third, it is based on
well-developed enterprise modelling languages and a distributed system archi-
tecture, which jointly position ODP as a perfect framework for modelling large,
cross-organizational and cross-jurisdictional systems that communicate over
the Internet. Finally, it has a well-integrated and fully developed treatment of
