Title: Multilayer Class
Authors: Jens Coldewey, Wolfgang Keller

EMail: {jensc|wk}@sdm.de

Snail Mail: software design & management GmbH&Co.KG
	    Thomas-Dehler-Strasse 27
	    D-81737 Muenchen
	    Germany

Phone:	    +49-89-63812-125 (Jens)
	    +49-89-63812-210 (Wolfgang)

Fax:	    +49-89-63812-490

Abstract:

The pattern describes a widely used, yet seldom confessed, method to separate 
layers by putting them into a single class. The Motivation discusses why other
standard solutions like Letter/Envelope or Observer do not work in
certain situations, where life cycles of objects in both layers are
tightly coupled. Though the solution looks pretty simple, several implemen-
tation issues have to be considered. This pattern is part of a larger effort
of our company to document our design knowledge in the field of business
information systems.