Network Deployment (Distributed operating systems), v8.0 > Product overview and quick start


WAS architecture

This topic introduces the parts of the WAS.


Servers

WAS. An application server is a JVM running user applications. Application servers use Java technology to extend web server capabilities to handle web application requests. An application server makes it possible for a server to generate a dynamic, customized response to a client request. The WAS provides application servers.

For more introduction, refer to Introduction: Application servers.

Generic servers. In distributed platforms, you can use the generic servers feature to create a generic server as an application server instance within the product administration, and associate it with a non-WebSphere server or process. The generic server can be associated with any server or process that is necessary to support the application server environment.

For more information, refer to Server collection.

Web servers. In the WAS, an application server works with a web server to handle requests for web applications. The application server and web server communicate using an HTTP plug-in for the web server.

For more information, refer to Implement a web server plug-in.


Clusters

Clusters. In the WAS ND, clusters and cluster members help you monitor application servers and manage the workloads of servers.

For more information, refer to Balancing workloads.


Core groups

Core groups settings. A core group is a statically defined component of the high availability manager. The high availability manager is a product function that monitors the application server environment and provides peer-to-peer failover of application server components.

Core group bridge settings. A core group bridge is a configurable service for communication between core groups.

For more information, refer to Core groups (high availability domains).


Resources

JMS providers. The product supports messaging by providing a range of JMS providers that conform to the JMS specifications. There are three main types of JMS provider that can be configured in WAS: The WAS default messaging provider (uses service integration as the provider), the WebSphere MQ messaging provider (uses your WebSphere MQ system as the provider) and 3rd party messaging providers (use another company's product as the provider).

For more information, refer to Introduction: Messaging resources.


Environment

Cell-wide settings help handle requests among Web applications, web containers, and application servers in a logical administrative domain called a cell.

Virtual hosts. A virtual host is a configuration enabling a single host to resemble multiple logical hosts. Each virtual host has a logical name and a list of one or more DNS aliases by which it is known. A DNS alias is the TCP/IP host name and port number that are used to request the servlet, for example: hostname:80. The DNS alias might be the host name and port of a web server that routes to the application server or the actual host name and port on which the application server is listening. Java EE web modules are mapped to a virtual host at installation time. Web modules that use the same virtual host can dispatch to resources within one another.

For more information, refer to Virtual hosts.

WebSphere variables. Variables are used to control settings and properties relating to the server environment. WebSphere variables are used to configure product path names such as JAVA_HOME, cell-wide customization values, and the WAS for z/OS location service.

For more information, refer to WebSphere variables.

Shared libraries. Shared libraries are files used by multiple applications. We can define a shared library at the cell, node, or server level. We can then associate the library to an application or server in order for the classes represented by the shared library to be loaded in either a server-wide or application-specific class loader.

For more information, refer to Manage shared libraries.

Replication domains. Replication is a service that transfers data, objects, or events among application servers. Data replication service (DRS) is the internal WAS component that replicates data. Replication domains transfer data, objects, or events for session manager, dynamic cache, or stateful session beans among application servers in a cluster.

For more information, refer to Data replication.


System administration

Administrative console. The administrative console is a graphical interface that provides many features to guide you through deployment and systems administration tasks. Use it to explore available management options.

For more introduction, refer to Introduction: Administrative console.

Scripting client (wsadmin). The WebSphere administrative (wsadmin) scripting program is a powerful, non-graphical command interpreter environment enabling you to run administrative operations in a scripting language. We can also submit scripting language programs to run. The wsadmin tool is intended for production environments and unattended operations.

For more introduction, refer to Introduction: Administrative scripting (wsadmin).

Administrative programs (Java Management Extensions). The product supports a Java programming interface for developing administrative programs. All of the administrative tools that are supplied with the product are written according to the API, which is based on the industry standard JMX specification.

For more introduction, refer to Introduction: Administrative programs.

Command line tools. Command-line tools are simple programs that you run from an operating system command-line prompt to perform specific tasks, as opposed to general purpose administration. Using the tools, you can start and stop application servers, check server status, add or remove nodes, and complete similar tasks.

For more introduction, refer to Introduction: Administrative commands.

Configuration files. Product configuration data resides in XML files that are manipulated by the previously mentioned administrative clients.

For more introduction, refer to Introduction: Administrative configuration data.

Domains (cells, nodes). Servers, nodes and node agents, cells, and the dmgr are fundamental concepts in the administrative universe of the product. It is also important to understand the various processes in the administrative topology and the operating environment in which they apply.

For more introduction, refer to Welcome to basic administrative architecture.


Monitor and tuning

Monitor tools. Performance monitoring is an activity in which you collect and analyze data about the performance of the applications and their environments. Performance monitoring tools include :

Tune tools. Tuning the product helps you obtain the best performance from your website. Tuning the product involves analyzing performance data and determining the optimal server configuration. This determination requires considerable knowledge about the various components in the application server and their performance characteristics. The performance advisors encapsulate this knowledge, analyze the performance data and provide configuration recommendations to improve the application server performance. Therefore, the performance advisors provide a starting point to the application server tuning process and help you without requiring that you become an expert.

For more information, refer to Obtaining advice from the advisors.


Troubleshoot

Diagnostic tools. Diagnostic tools help you isolate the source of problems. Many diagnostic tools are available for this product.

For more information, refer to Work with troubleshooting tools.

Support and self-help IBM Support can assist in deciphering the output of diagnostic tools. Refer to the WAS Technical Support website for current information on known problems and their resolution. Documents at this site can save you time gathering information that is needed to resolve a problem.

For more information, refer to the WAS Support page.


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