WAS Network Deployment components
The following is a short introduction for each WebSphere Network Deployment runtime component and their functions:
Deployment Manager
The Deployment Manager is part of an WAS Network Deployment V5.x installation. It provides a central point of administrative control for all elements in a distributed WebSphere cell. Deployment Manager is a required component for any vertical or horizontal scaling and there exists only one specimen of it at a time.
Node Agent
The Node Agent communicates directly with the Deployment Manager, and is used for configuration synchronization and administrative tasks such as stopping/starting of individual appservers and performance monitoring on the application server node.
Application server (instance)
An appserver in WebSphere is the process that is used to run your servlet and/or EJB-based applications, providing both Web container and EJB container.
Web server and Web server plug-in
While the Web server is not strictly part of the WebSphere runtime, WebSphere communicates with your Web server of choice: IBM HTTP Server powered by Apache, Microsoft® Internet Information Server, Apache, Sun ONE Web server, and Lotus® Domino via a plug-in. This plug-in communicates requests from the Web server to the WebSphere runtime.
Embedded HTTP transport
The embedded HTTP transport is a service of the Web container. An HTTP client connects to a Web server and the HTTP plug-in forwards the requests to the embedded HTTP transport. The communication type is either HTTP or HTTPS between the plug-in and the embedded HTTP transport.
Although the embedded HTTP transport is available in any WAS to allow testing or development of the application functionality prior to deployment, it should not be used for production environments.
Embedded Messaging (JMS) Server
The JMS server was introduced with WAS V5 (all versions except WebSphere Express). The JMS server is a complete messaging server that supports point-to-point and publish/subscribe styles of messaging.
Administrative service
The administrative service runs within each WAS Java virtual machine (JVM.) Depending on the version installed, there can be administrative services installed in many locations. In WAS V5.0 and higher, the administrative service runs in each appserver. In a Network Deployment configuration, the Deployment Manager, Node Agent, application server(s), and JMS server all host an administrative service. This service provides the ability to update configuration data for the application server and its related components.
Administrative Console
The WebSphere Administrative Console provides an easy-to-use, graphical "window" to a WebSphere cell, runs in a browser, and connects directly to a WebSphere V5.1 server or to a Deployment Manager node that manages all nodes in a cell.
Configuration repository
The configuration repository stores the configuration for all WAS components inside a WebSphere cell. The Deployment Manager communicates changes in configuration and runtime state to all cell members through the configuration repository.
Administrative cell
A cell is a set of Application Servers managed by the same Deployment Manager. Some appserver instances may reside on the same node, others on different nodes. Cell members not necessarily run the same application.
Server cluster
A server cluster is a set of appserver processes. They run the same application but usually on different nodes. The main purpose of clusters is load balancing and failover.
Figure 1-2 WebSphere configuration with Java clients and Web clients
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IBM is a trademark of the IBM Corporation in the United States, other countries, or both.