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Weblogic Application Server FAQs

81.Why the JNDI required in Weblogic?
In Oracle WebLogic Server, JNDI serves as a repository and lookup service for J2EE objects, including:

    • Enterprise JavaBeans (EJB) home stubs
    • JDBC DataSources
    • JMS connection factories, queues, and topics
    • Remote Method Invocation (RMI) stubs

82.What is the use of Naming Services?
A naming service provides a method for mapping identifiers to entities or objects.


Term

Definition

Example

Binding

The association of an atomic name and an object

www.example.com is bound to 209.10.217.38.

Namespace

A set of unique names in a naming system

www.example.com/ products

83.Explain about Contexts and Sub-contexts in JNDI?

    • Subcontexts are referenced through the dot delimiters (.).
    • The subcontexts must be created before objects are placed into them.
    • Typically when objects are bound to a JNDI tree, subcontexts are automatically created based on the JNDI name.

 If the following context exists:  com.oracle.examples
You cannot bind:  com.oracle.examples.ejb.SomeObject
Without first creating:  com.oracle.examples.ejb

84.How can I set deployment order for applications?
 WebLogic Server 8.1 allows you to select the load order for applications. See the ApplicationMBean LoadOrder attribute in Application. WebLogic Server deploys server-level resources (first JDBC and then JMS) before deploying applications. Applications are deployed in this order: connectors, then EJBs, then web Applications. If the application is an EAR, the individual components are loaded in the order in which they are declared in the application.xml deployment descriptor.
85.Can I refresh static components of a deployed application without having to redeploy the entire application?
Yes. You can use weblogic.Deployer to specify a component and target a server, using the following syntax:
java weblogic.Deployer -adminurl http://admin:7001 -name appname -targets server1,server2 -deploy jsps/*.jsp

86.When should I use the -nostage option?
Set the staging mode to -nostage (using weblogic.Deployer or the Administration Console) if you don't want to copy deployment files but want to deploy an application from its present location. All target servers must be able to access the same set of deployment files.
87.When should I use the external_stage option?
Set -external_stage using weblogic.Deployer if you want to stage the application yourself, and prefer to copy it to its target by your own means.
88.What are the Deployment Tools for Developers?
WebLogic Server provides several tools for deploying applications and stand-alone modules:

  • wldeploy is an Ant task version of the weblogic.Deployer utility. You can automate deployment tasks by placing wldeploy commands in an Ant build.xml file and running Ant to execute the commands.
  • weblogic.PlanGenerator is a command-line tools that enables developers to export an application’s configuration for deployment to multiple WebLogic Server environments.
  • The deployment API allows you to perform deployment tasks programmatically using Java classes.
  • The autodeploy domain directory allows you to deploy an application quickly for evaluation or testing in a development environment.

89.What is the Deployment order of Weblogic Server at Server Startup time?
By default, WebLogic Server deploys applications and resources in the following order:

  • JDBC system modules
  • JMS system modules
  • J2EE Libraries and optional packages
  • Applications and stand-alone modules
  • Startup classes

Note: WebLogic Server security services are always initialized before server resources, applications, and startup classes are deployed. For this reason, you cannot configure custom security providers using startup classes, nor can custom security provider implementations rely on deployed server resources such as JDBC.
90.How will you “Kill the JVM” or running Weblogic server in different operating systems?
Each WebLogic Server instance runs in its own JVM. If you are unable to shut down a server instance using the scripts which are provided by the Weblogic (stopWeblogic.cmd/ stopManagedWeblogic.cmd), you can use an operating system command to kill the JVM.

Caution: If you kill the JVM, the server immediately stops all processing. Any session data is lost. If you kill the JVM for an Administration Server while the server is writing to the config.xml file, you can corrupt the config.xml file.

Some common ways to kill the JVM are as follows:

  • If the shell (command prompt) in which you start the server is still open, you can type Ctrl-C.
  • On a Windows computer, you can use the Task Manager to kill a JVM.

On a UNIX computer, you can use the “ps” command to list all running processes. Then you can use the kill command to kill the JVM .