Domain , Administration & Managed Server, Cluster in Oracle WebLogic

What is domain in WebLogic ?

WebLogic Domain

Domain is logical grouping of resources and services and consist of Administration Server, Managed Server and cluster. There can only be one administration Server in domain and zero to N Managed Server.

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What is Administration Server ?

Administration Server is WebLogic Server instance that maintains configuration data for a domain. You can deploy your application on administration Server but it is recommended to create managed Server and deploy your application in managed server and leave Administration domain for configuration and maintenance.

—There will always be atleast one Administration Server in a domain.

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What is Managed Server ?

Any WebLogic Server instance apart from Administration Server is called as Managed Servers. This is weblogic server where you deploy your application (Though you can deploy your application in Administration server as well but it is not recommended in production/UAT instance)

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What is Cluster in WebLogic ?

Group of WebLogic Managed Server Instances that work together to provide high availability and scalability for applications is called cluster. WebLogic Servers with in cluster can run on same machine or different machines. These are also called as managed Server cluster.

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Things you should know before creating domain in WebLogic Server ?

– You use configuration wizard to create or extend domain but this can be used only in offline mode (when weblogic server is not running)
– You can also use WLST (WebLogic Scripting Tool), command line tool to create and extend domains in WebLogic Server.
– You can also use unpack command to create new domain. This command can’t be used to extend domain.
– Extending a domain means, you already created domain and now wish to extend it (use more application, add managed server, create cluster…)
– Configuration wizard can be run in Graphical Mode (interactive GUI) or Console Mode (interactive text based)
– For silent mode use WLST (WebLogic Scripting Tool)
– While creating domain you specify Startup Mode (Development or Production). In development mode, you get autodeploy option and security is low. In production mode you need username/password to deploy applications.
– When you create domain, it creates following directories
i) autodeploy ii) bin iii) config (config.xml for domain sits here) iv) console-ext v) lib vi) security vii) servers

–You use config.cmd (windows) or config.sh (unix) from $BEA_HOME/ wlserver_/ common/ bin to start configuration manager to create domain

Below Flowchart (image from Oracle Documentation) displays steps to create domain.
Create WebLogic Domain