When it comes to frameworks, the familiar story of the elephant and the
six blind philosophers seems to apply. As each philoso- pher encountered
a separate part of the elephant, each pronounced his considered, but
flawed judgement. One blind philosopher felt a leg and thought it a
tree. Another felt the tail and thought he held a rope. Another felt the
elephant's flank and thought he stood before a wall. We're supposed to
learn about snap judgements from this alle- gory, but its author might
well have been describing design automation frameworks. For in the
reality of today's product development requirements, a framework must be
many things to many people. xiv CAD Frameworks: Integration Technology
for CAD As the authors of this book note, framework design is an optimi-
zation problem. Somehow, it has to be both a superior rope for one and a
tremendous tree for another. Somehow it needs to provide a standard
environment for exploiting the full potential of computer-aided
engineering tools. And, somehow, it has to make real such abstractions
as interoperability and interchangeability. For years, we've talked
about a framework as something that provides application-oriented
services, just as an operating system provides system-level support. And
for years, that simple statement has hid the tremendous complexity of
actually providing those services.