An excellent book on software architectures is [Practice].
You may also want to visit the SEI architecture site at
www.sei.cmu.edu/architecture, which
provides definitions, and a wealth of other
information.
As a discussion of the software engineering implications
of CORBA, you may want to read [CorbaPatterns].
If you are interested in multimedia information systems,
read [MM]. For more information on ACOI,
visit the ACOI website on www.cwi.nl/~acoi .