From sk@cs.brown.edu  Thu Oct  4 00:04:28 2001
From: Shriram Krishnamurthi <sk@cs.brown.edu>
To: Mirek Kula <Mirek.Kula@GTECH.COM>, Jean Laleuf <jrl@cs.brown.edu>,
   Jay Lepreau <lepreau@cs.utah.edu>, Karl Lieberherr <lieberherr@ccs.neu.edu>,
   Jim Waldo <Jim.Waldo@Sun.COM>, Mark N Wegman <wegman@us.ibm.com>
Subject: defining components

Hi Shriram:

I will use a definition similar to the following
(from a Schloss Dagstuhl workshop, prepared with Mira Mezini).
Covers components that are aspects.

What is a component?
any identifiable slice of functionality that describes a meaningful service,
involving, in general, several concepts,

with well-defined expected and provided interfaces,
formulated for an ideal ontology - the expected interface
subject to deployment into several concrete ontologies by 3rd parties
subject to composition by 3rd parties
subject to refinement by 3rd parties

An ontology is, in simple terms, a collection of concepts with
relations among them plus constraints on the relations.

Deployment is mapping idealized ontology to concrete ontology
specified by adapters separately from components
without mentioning irrelevant details of concrete ontology in map to keep
deployment flexible
non-intrusive, parallel, and dynamic deployment

Composition is mapping the provided interface of one (lower-level) component
to the expected interface of another (higher-level) component

Deployment is a special case of composition, where the lower level
     component is  a concrete ontology (no expected interface)

-- Karl


Dear IPP Speakers,

As you know well, in this area we often find disagreement and
confusion sometimes springs from two parties using different
definitions or notions of "components".  Just as an example, some
people contend that every Java class is already a component, so people
practicing class-oriented Java programming are already practicing
component-oriented programming; others demand much more.

It's not important that we agree on a definition (nor do I expect we
can reach agreement).  It would, however, help if your talk lays out,
as informally as you wish, your notion of components.  I believe it
would help the audience to know your position concretely so they can
contrast it to that of others.

Hope this isn't too much of an imposition.

Thanks,
Shriram