Oracle WebLogic Server (2022 Updated)

WebLogic server is an Oracle solution. It is a Java-based application server which can host Java-based applications. Enterprise applications can be developed and deployed in a WebLogic server, in order to deliver the business logic. To put it in layman’s words, with a WebLogic server we can easily deploy, distribute, run Java-based applications.

Following are the basic components of a WebLogic server:

• Domains
• Node Manager
• Admin server
• Managed server
• WebLogic server cluster

Domains are logical sets of resources within Oracle WebLogic Server that constitute a single unit. This includes an Administration Server, from which you configure and manage all resources in the domain. It can separate the variety of environments and the complexity of the workplace.

WebLogic is a specialized Application server that can host both Web applications and Enterprise applications. We cannot run WebLogic hosting Enterprise Applications, such as .ear files, on a less specialized server such as Tomcat.

Following are the various thread states in a WebLogic server:

• STUCK
• HOGGER
• ACTIVE
• STANDBY
• IDLE

WebLogic installation can happen via 3 different modes:

Console mode: This installation mode is based on interactive text messages.

Graphical mode: This installation mode is based on the interactive GUI.

Silent mode: This installation mode is based on the properties file that is provided with it, which doesn’t require any interaction as such.

Stage mode can be understood as the default (and preferred) mode when deploying to more than one WebLogic Server instance while the non-stage mode indicates that the Admin Server does not copy the archive files from their source location.

Deployment descriptors are associated with modules and applications alike. They can be seen in the form of XML documents, and can tell what to do with the contents of the directory or jar file. J2EE standards usually include standards as well as the deployment descriptors that can be used by any J2EE application or module.

A web.xml is an XML document and mainly used for configuring J2EE components in an application. It mainly functions by outlining the list of the components and configurations of the application in a J2EE module format.

IIOP is a kind of protocol helpful in enabling the communication between WebLogic server and object request broker.

T3 can provide structure or overall design for the messages that it’s capable of enhancing. The functionality or enhancements that it’s capable of supporting includes: product tunneling, working in the context of clusters of WebLogic servers, and also, object replacement.

With a server crash, there is no existence for the Java process and if it is a server hang, then the Java process stops responding.

The major reasons for the occurrence of server crash are the native IO, JVM, supported configuration, JDBC driver issues and SSL native libraries.

Java WebLogic.Admin PING needs to be checked for finding whether you get a normal and positive response. You can find out the root cause for hanging from this file. You just need to rectify the errors that are identified from this file.

Memory leak is the condition that arises when the objects get retained in the heap even after they have no use.

There are various reasons that can lead to this condition and they are

• Insufficient size of the heap compared to the extra load.
• Placing of the objects takes longer period of time like that of HTTP sessions.
• Occurrence of memory leak inside the application code.
• The prevention of occurrence of full GC because of JVM bug.

Clustering is the act of grouping the servers for purposes of improving the level of scalability and availability.

You can use the script files from WebLogic to set CLASSPATH for the requirements. These are the files that we have to use based on the OS type (Windows or Linux):

1. WL_HOME/server/bin/setWLSEnv.cmd for Windows

2. WL_HOME/server/bin/setWLSEnv.sh for Linux

Auto deployment mode feature of WebLogic server works for the development mode, where it checks every 3 seconds to see if there are any new applications available or any new changes available for the existing applications and deploys them. To disable the automatic deployment, these are the available options:

1. Selecting the Production mode checkbox from the Administration Console for the necessary domain.

2. On CLI, use option -Dweblogic.ProductionModeEnabled=true when starting the respective domain’s Administration Server.

WebLogic Smart Update or BEA Smart Update utility (BSU) is a utility available to update or apply patches on WebLogic Servers. It can be found under the following folder (WL_HOME/utils/bsu).

A stateless system sends a request to the server and relays the response (or the state) back without storing any information. On the other hand, stateful systems expect a response, track information, and resend the request if no response is received.