Understanding Domain Configuration

Introduction and Roadmap

This document describes WebLogic Server® domains and how they are configured. A domain is the basic administration unit for WebLogic Server. A domain consists of one or more WebLogic Server instances (and their associated resources) that you manage with a single Administration Server.

The following sections describe the contents and organization of this guide—Understanding Domain Configuration.

Document Scope and Audience

This document is written mainly for J2EE system architects, application developers, and system administrators who are developing or deploying Web-based applications on one or more WebLogic server domains.

The topics in this document are relevant during the design and development phases of a software project. This document does not address production phase administration, monitoring, or performance tuning topics. For links to WebLogic Server documentation and resources for these topics, see Related Documentation.

It is assumed that the reader is familiar with J2EE, basic concepts of XML, and general networking and application management concepts.

Guide to this Document

This chapter, Introduction and Roadmap, introduces the purpose, organization, and context of this guide.
Understanding WebLogic Server Domains, introduces WebLogic Server domains.
Domain Configuration Files, describes the configuration and directories that maintain the on-disk representation of a domain and its contents.
Managing Configuration Changes, describes change management features in WebLogic Server.

Samples and Tutorials

In addition to this document, BEA Systems provides code samples and tutorials that are relevant to domain configuration and administration.

The BEA WebLogic Server Examples are optionally installed at WL_HOME/samples/server/examples/src/examples, where WL_HOME is the top-level directory of your WebLogic Server installation. These examples are also available from the Start menu on Windows machines. These examples include:

WebLogic Scripting Tool Online Scripts example, which shows how to use the WebLogic Scripting Tool (WLST) to interact and configure a running WebLogic Administration server.
The Clustering example, which leads you through the process of creating and configuring a new cluster of server instances in a domain using the WebLogic Configuration Wizard and Administration Console.

The Avitek Medical Records Sample Application is a WebLogic Server sample application suite that concisely demonstrates all aspects of the J2EE platform. It includes:

a demonstration of the use of JMX to extend a security realm

New and Changed Domain Features in This Release

WebLogic Server 9.0 introduces several important changes to WebLogic Server domain configuration:

XML Schema for config.xml

The on-disk representation of the configuration of WebLogic Server domains and instances has changed in this release. In previous releases, configuration information was persisted in a single XML repository file named config.xml, which was located by default in the user_projects/domains/DOMAIN_NAME folder. In this release of WebLogic Server, the config.xml file adheres to an XML Schema definition that can be used to validate the domain configuration file format. In addition, config.xml incorporates configuration information from other configuration files, which adhere to their own XML Schemas. In this release, config.xml is located by default in the user_projects/domains/DOMAIN_NAME/config folder, while the subsidiary configuration files to which the central config.xml file refers are located in subfolders under the user_projects/domains/DOMAIN_NAME/config folder. For more information, see Domain Configuration Files.

Domain Directory Structure

The directory structure that holds the on-disk representation of WebLogic Server domains has changed in this release. The parent directory for a domain is a directory named domains. Configuration information for the domain is kept in the domains/DOMAIN_NAME/config directory, and in subdirectories of the config directory. For more information, see Domain Directory Contents.

Configuration Change Management

WebLogic Server provides new features to manage changes to server configuration, which enable you to implement a secure, predictable means for distributing configuration changes in a domain. It also requires you first to obtain a lock in the Administration Console before you use the console to make any configuration changes.

The change management process in WebLogic Server loosely resembles a database transaction. The Administration Server maintains a separate, editable representation of the domain's configuration, which is referred to as the edit hierarchy. Server instances do not refer to the edit hierarchy. Instead, server instances use a read-only hierarchy to discover their configuration. To start the edit process, you obtain a lock on the edit hierarchy to prevent other people from making changes. When you finish making changes, you save and distribute them to all server instances in the domain. When you distribute changes, each server determines whether it can accept the change. If all servers are able to accept the change, they update their working configuration hierarchy and the change is completed.

The Administration Console now includes a pane named the Change Center. When you use the Administration Console to make a configuration change, you must first obtain a lock by clicking Lock & Make Changes in the Change Center. Make any desired configuration changes, then in the Change Center either:

click Activate Changes to accept the changes and distribute them to the server instances in the domain, or
click Undo All Changes to roll back the changes and release the lock.

WebLogic Server controls configuration changes in generally the same manner, whether the changes are implemented using the Administration Console, the WebLogic Scripting Tool, or the JMX APIs.

For more information, see Managing Configuration Changes.