Welcome to basic administrative architecture
The basic administrative architecture consists of software processes called servers, topological units referenced as nodes and cells, and the configuration repository used for storing configuration information. The application server, node agent server, deployment manager, administrative agent, and job manager interact to perform system administration.
This topic discusses basic concepts in the administrative architecture to help we understand system administration in a WebSphere Application Server environment.
Servers perform the actual running of the code. Several types of servers exist depending on the configuration. Each server runs in its own JVM. The application server is the primary runtime component in all WAS configurations. All WAS configurations can have one or more application servers. In some configurations, each application server functions as a separate entity. No workload distribution or common administration among application servers exists. In other configurations, workload can be distributed between servers and administration can be done from a central point.
A node is a logical group of WAS-managed server processes that share a common configuration repository. A node is associated with a single profile. A node does not necessarily have a one-to-one association with a system. One computer can host arbitrarily many nodes, but a node cannot span multiple computer systems. A node can contain zero or more application servers.
The configuration repository holds copies of the individual component configuration documents that define the configuration of a WAS environment. All configuration information is stored in .xml files.
A cell is a grouping of nodes into a single administrative domain. A cell can consist of multiple nodes, all administered from a deployment manager server. When a node becomes part of a cell (a federated node), a node agent server is created on the node to work with the deployment manager server to manage the WAS environment on that node.
When a node is a stand-alone node, not part of a cell, the configuration repository is fully contained on the node. When a stand-alone node is registered with an administrative agent, the configuration repository continues to be fully contained on the node. When a node is part of a cell, the configuration and application files for all nodes in the cell are centralized into a cell master configuration repository. This centralized repository is managed by the deployment manager server and synchronized to local copies that are held on each node. The local copy of the repository givenn to each node contains just the configuration information needed by that node, not the full configuration that is maintained by the deployment manager. When a deployment manager is registered with a job manager, the deployment manager continues to manage the centralized configuration repository.
WAS types
This section discusses the server types that interact to perform system administration.
- Application server
- The product provides functions that support and host user applications. An application server can run on only one node, but one node can support many application servers.
- Node agent
- When a node is federated, a node agent is created and installed on that node. The node agent works with the deployment manager to perform administrative activities on the node.
- Deployment manager
- With the deployment manager, we can administer multiple nodes from one centralized manager. The deployment manager works with the node agent on each node to manage all the servers in a distributed topology. Application server nodes must be federated with the deployment manager before they can be managed by the deployment manager.
- Administrative agent
- An administrative agent provides a single interface to administer unfederated application server nodes in environments such as development, unit test, or that portion of a server farm that resides on a single computer. Application servers nodes must be registered with the administrative agent before they can be managed by the administrative agent.
- Job manager
- In a flexible management environment, a job manager enables us to submit administrative jobs asynchronously for application server nodes registered to administrative agents and for deployment managers. Application server nodes managed by an administrative agent or deployment manager must be registered with the job manager before the job manager can manage them.
The following diagram depicts the concepts that are discussed in this topic.
The concepts that are discussed in this topic form the basis of WAS administration. ore detailed descriptions can be found in other sections.