At the request of the authors, the text of this paper has been removed from the PLoP-97 technical report. For more information please contact the authors directly. Title of the paper: Cascade Ted Foster ted@class-sc.demon.co.uk Class Software Construction Ltd. 4 Duchy Road, Harrogate, North Yorkshire, HG1 2EP, England Tel. & Fax: +44 1423 503301 Liping Zhao liping@cs.rmit.edu.au Department of Computer Science RMIT, Bundoora Campus Bundoora, Victoria, 3083, Australia Tel. +61 3 9407 6123 Fax +61 3 9407 6139 ABSTRACT Cascade is a generic pattern for layering and ordering the parts of a complex whole. Each layer is itself a Composite pattern which composes objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly. Cascade makes the layering and ordering of objects and their compositions explicit. Cascade has the ability to treat one Composite layer as a primitive Component of its parent layer and hence allows us to express the relationship between parts and wholes naturally: a whole for one particular layer is simply a part for the next layer up. In our modelling of transport systems, we have observed frequent recurrence of the Cascade pattern. We believe that many real world problems exhibit the features of Cascade. In this paper, we illustrate Cascade with more examples from transport systems. Subject area: software pattern