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From: Daniel Kulp <dkulp@apache.org>
To: dev@cxf.apache.org
Subject: Re: [Discuss] CXF Architecture and Architecture Documentation
Date: Mon, 21 Feb 2011 12:56:08 -0500
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Cc: Christian Schneider <chris@die-schneider.net>
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> "Architecture is the sum of the decisions about a project that are the
> most expensive to change later. "

The "decision" to not have up to date achitecture docs is one of the =20
"decisions about a project that are the most expensive to change later".   =
:-)

Not saying it shouldn't be fixed, it's just going to be expensive to fix fr=
om=20
a time perspective.   :-)


Dan


On Saturday 19 February 2011 7:31:21 AM Christian Schneider wrote:
> Hi All,
>=20
> I know that the theme is a big one and likely will spawn some larger
> discussion still I think it is important to talk about it and to have a
> common understanding.
> When digging into some not so obvious issues I repeatedly stumble about
> the fact that there are important things about CXF that I don=C2=B4t know=
 or
> only have a vague clue of.
> Another problem I often had is where to put new stuff or decide if a
> classs is placed at a location where it should not be.
>=20
> These examples show in my opinion that we do not have a good
> architecture documentation and no clean process to decide about
> architecture and to document decisions. So I propose some things
> and we see if we reach a consensus.
>=20
> The first thing is a question that always pops up and that is not so
> easy. What is architecture?
> I once read a nice definition that is quite open but still catches what
> is important:
> "Architecture is the sum of the decisions about a project that are the
> most expensive to change later. "
> Sorry that I am not able to point to a concret source of this. I think
> this definition catches the important thing about architecture. It
> should cover only those things that may later bite you.
> So for example the decision it can be argued if the decision for a
> logging framework is an architectural decision as we saw in Apache Camel
> how fast they were able to switch to slf4j. So this was nothing
> that was expensive to change. In any case I am curious what you guys
> consider as a good definition for an architecture.
>=20
> I would like to come to a consensus about what we define as architecture
> as a first starting point.
>=20
> The next thing is how to document our architecture. We have a good
> starting point at
> https://cwiki.apache.org/confluence/display/CXF20DOC/CXF+Architecture
> but I think some important things are lacking. This page
> describes the key structural elements and how some key elements work
> together in CXF. That is very important and we should simply try to
> improve it. I would also like to add our common definition of what
> architecture is to that document.
>=20
> The first thing I would like to add are architectural goals. An
> architecture can never be good in itself. It can only be judged against
> the goals it tries to achieve. Here again we should only track the most
> important goals.
>=20
> The second thing I would like to add is a page about architectural
> decisions. It should contain a short description of the process how we
> do these decisions and a list of decisions in a well defined format. I
> would also like
> to limit the decisions to a certain number so we are sure that only the
> most important decisions are tracked. I added such a page as my proposal
> and we should discuss if this is ok for all. As I have no idea how many
> decisions we should track I think we could simply start and keep in mind
> that it should not grow too large. See
> https://cwiki.apache.org/confluence/display/CXF20DOC/Architectural+Decisi=
on
> s
>=20
> I hope we reach a consensus about these things as I think they are very
> important.
>=20
> Christian

=2D-=20
Daniel Kulp
dkulp@apache.org
http://dankulp.com/blog
Talend - http://www.talend.com