Imagine deploying an enterprise application to several instances of WebLogic Server (some of which may be clustered) spread across a handful of machines with different physical and network characteristics. How can you easily manage the disparate deployments on the different server instances, the different cluster configurations, the heterogeneous machines, and the multiple networks? The J2EE specification prescribes the environment and architecture for building Java applications using standard enterprise APIs. However, it does not deal with the issues of managing deployment across multiple servers and heterogeneous machines, configuring a cluster of servers for high availability and failover, or administering services and resources across multiple servers on different machines. The J2EE standard lets application server vendors implement these features using any proprietary approach. WebLogic supports the concept of domains, which satisfies these very requirements.
Domains lie at the heart of WebLogic administration, and you need to create a domain before you can use any of the resources described in this book. This chapter explains what domains are, how to create a domain, how to back up the data in a domain, and how to configure the network characteristics of a domain. It also looks at how to create and use node managers, which provide a way of monitoring and controlling the life cycle of managed servers within a domain.