The purpose of this paper is to apply twenty-twenty hindsight and the perspective of the Design Patterns and Dependency Injection movements to the Central Authentication Service version 2.0 "auth" authentication handling package. CAS has served Yale and others well since its inception and those involved in its design, implementation, and maintenance deserve a great deal of credit for its success. Nonetheless, an examination of the CAS 2.0 "AuthHandler" interface and its extensions and implementations reveals opportunites for improvement.
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