Are you working with Oracle Application Server ? If you are familiar with the architecture of Oracle AS then a comparison study would be easy to grasp the Weblogic concepts. Here are some of my observations during my Weblogic study phase – This way it is easy to remember basics.

Architecture Comparison

  • In Oracle AS 10g R3 Application Server Control is active on only one instance (identified as Administration instance in a cluster) even though it manages other associated Oracle AS instances. Similarly, in Oracle WebLogic Server the Administrative Console is active only on one server instance (Administration Server) but can manage other server instances (Managed Servers) in a domain.
  • In Oracle AS 10g Release 2 there is a central configuration repository managed by Distributed Configuration Management (DCM). In Oracle WebLogic Server also there is a central configuration repository (config.xml).
  • In Oracle AS 10g Release 2, all the instances that shared the configuration repository constituted a topology element called Farm. The Farm is similar to a Domain in Oracle WebLogic Server.
  • The weblogic server is an instance of weblogic.server, which executes in a Java Virtual Machine (JVM). This is similar to an Oracle AS instance with just an OC4J container.
  • Managed server is an oracle weblogic server instance that hosts business applications, application components, web services and associated resources. It is similar to an Oracle AS 10gR3 without the management components.
  • Administration Server and OC4J Administration Instance – Administration Server stores the master copy of the domain configuration, including the configuration for all the Managed Servers in the domain. In this way, it functions as an Oracle AS instance that contains the file-based repository.
  • An Oracle WebLogic Server cluster consists of multiple Oracle WebLogic Server instances. This is similar to an OC4J cluster in Oracle AS. When you configure an Oracle AS Cluster (OC4J), you can use the Oracle HTTP Server as the front end. The load balancing directives are configured in the mod_oc4j configuration of the front-end Oracle HTTP Server. When you configure an Oracle WLS cluster, you should configure a mechanism such as an Apache or a non-clustered WLS instance to function as the front end for the cluster. You should also configure the load balancing within the cluster and not at the front end.

Administration and Installation

  • An Oracle Application Server has integrated installation and configuration where as Weblogic server separates installation of binaries using the installer and configuration of domains that contains the servers by using domain configuration wizard.
  • Admin Console: A web application with GUI that is used to manage and monitor an active domain. This is similar to the Oracle Application Server Control Console.
  • Weblogic Scripting Tool (WLST): A command line scripting interface that you use to manage and monitor an active or inactive weblogic server domain. This is similar to the OPMNCTL and DCMCTL tools but has more capabilities.

Oracle Weblogic Server 11g Evolution History

Reference: Oracle Weblogic Library


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