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CAS Internals: A Journey Through the Central Authentication Server Codebase
This book is 100% completeLast updated on 2026-03-18
Across 30 chapters, you'll trace real code paths through nearly 400 CAS modules, learning the architecture decisions, design patterns, and implementation techniques that hold this massive system together. Whether you're a CAS contributor trying to fix a tricky bug, an architect evaluating CAS for your organization, or a Java developer who wants to study a mature, real-world Spring Boot application at scale — this book gives you the map.
Written by a long-time CAS committer who has been involved since the original CAS 3.0 architecture, this book distills years of hard-won knowledge into a single, code-level reference.
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Ever wondered what actually happens inside CAS when a user clicks "Log In"?
CAS Internals takes you on a guided tour through the source code of Apereo CAS 7.3 — the most widely deployed open-source single sign-on system in higher education and enterprise. This isn't another configuration guide. This book cracks open the hood and shows you how the engine works: the Spring Boot bootstrap sequence, the Webflow state machines driving the login flow, the ticket registry lifecycle, the protocol engines for SAML2, OAuth2 and OIDC, the cipher and JWT infrastructure, and much more.
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About the Author
Dmitriy Kopylenko
Dmitriy is an IAM specialist with deep expertise in Apereo CAS, Shibboleth IdP, SAML, OAuth2, and OIDC protocols. He has been a long-time committer to CAS and was involved with CAS since the original CAS 3.0 architecture and implementation.
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