Peter Eeles is a Technical Lead in Rational's Regional Services Organization, based in the UK. He has spent the
majority of his 16 year career developing large-scale distributed systems and, in 1998, co-authored his first book,
"Building Business Objects". A regular speaker at conferences throughout Europe, Peter spends most of his time
consulting in software architecture, and in helping organization adopt the Rational Unified Process. He lives in the UK
with his wife, Karen, and sons Daniel, Thomas and Christopher. Peter can be reached via e-mail at firstname.lastname@example.org. .
A number of techniques exist for decomposing software systems. Layering is one example and is described in this paper.
Such techniques address two main concerns: most systems are too complex to comprehend in their entirety, and different
perspectives of a system are required for different audiences.
Layering has been adopted in numerous software systems, and is espoused in many texts and also in the Rational Unified
Process (RUP). However, layering is often misunderstood and incorrectly applied. This paper clarifies what is meant be
layering, and discusses the impact of applying different layering strategies.