WebLogic 应用服务器有如下几个基本概念：
Domain: 域是个逻辑概念，用来组织管理一系列的应用服务器实例，也就是下面要解释的server. 域是WebLogic应用服务器中最大的概念，WebLogic应用服务器启动的时候就是以某个域来启动的，它有一个中心配置文件叫config.xml.
A domain is the basic administration unit for WebLogic Server instances (servers) that is represented in its own configuration file (config.xml). A domain consists of one or more servers (and their associated resources) that you manage with a single Administration Server.
Cluster: 族也是一个逻辑概念，用来分组用途相同的服务器实例，一个域中可以有多个族。
A cluster is a deployment in which multiple WebLogic Server instances (servers) run simultaneously and work together to provide increased scalability and reliability. A cluster appears to clients to be a single WebLogic Server instance. The servers that constitute a cluster can run on the same machine, or be located on different machines.
Machine: 机器是物理上的概念，代表一台运行WebLogic应用服务器的实在的机器，包括其IP地址等信息。一个域中可以包括多台机器。（同一台机器可以属于不同的域吗？）
A machine is the logical representation of the computer that hosts one or more WebLogic Server instances (servers). WebLogic Server uses configured machine names to determine the optimum server in a cluster to which certain tasks, such as HTTP session replication, are delegated. The Administration Server uses the machine definition in conjunction with the Node Manager application to start remote servers.
Server: 服务器，也就是一个应用服务器的实例，用来部署和运行各种J2EE应用程序，也可以来配置各种服务程序。它是WebLogic应用服务器的基本服务单元。一个WebLogic域中一般有一个管理服务器和多个被管理服务器。也就是下面我们要谈到的两个概念。
A server is an instance of WebLogic Server that runs in its own Java Virtual Machine (JVM) and has its own configuration. Each WebLogic Server domain must have one server that acts as the Administration Server. In a typical production environment, the Administration Server is where the Administration Console is run and used to perform administrative tasks. By default, the Administration Server is called myserver. A typical production environment may also have one or more Managed Servers, which are instances of WebLogic Server used to host enterprise applications.
Administrative Server: 管理服务器是用来管理配置域的中心点，一般来说，管理服务器上是不部署应用程序的，而是用来统一管理、配置、监控被管理服务器以及部署应用程序到被管理服务器上。一个域中有一台管理服务器。
Managed Server: 被管理服务器是用来部署运行各种应用程序的。一个域中有一台或多台被管理服务器。
Node Manager: 节点管理器是一个单独运行的后台程序，一般运行在被管理服务器的机器上，用来提供远程启动和停止服务器（Server）的功能。