Chapter 5: Geronimo Architecture and Directory Structure

Overview

Chapter 4 introduced Geronimo as a J2EE server. An under-the-hood exploration reveals the J2EE components inside the Geronimo server. What may not be evident, however, is that Geronimo is not limited to being a J2EE server from the architectural point of view. In fact, J2EE server is just one of the many different personalities that a Geronimo server can take on. This chapter sets the facts straight and examines the internal architecture of the Geronimo server.

Understanding the architecture of Geronimo is vital for administrators and deployers, because it allows you to leverage the flexibility built right into the very core of Geronimo. Namely, the concepts of GBean, module, and assembly are pervasive throughout Geronimo. This chapter introduces these concepts from scratch and shows how the Geronimo server is divided internally into components.

Configuration management is a key feature that Geronimo provides to all its components. This chapter explores this very important concept. Installed modules are stored (between reboots of the server) in a repository. The Geronimo repository is where Geronimo keeps all its service components and dependent libraries, as well as module configuration information. The chapter provides a detailed account of how the repository works in Geronimo.

The repository is kept as part of Geronimo’s directory structure. This chapter explores this directory structure in detail, showing the subdirectories, their contents, and their purpose with respect to the server’s operation.

This chapter also revisits the config.xml file that you examined in Chapter 2 and goes further in depth on the GBean customization options that this file provides.