WEBLOGIC SERVER FAQ(ANS)--6

weblogic interview questions and answers

61.What is the user of Log Filters in Weblogic?

Log filters:

• Control the log messages that get published
• Are based on the values of message attributes
• Can be applied to different message destinations:
• Server log file
• Server memory buffer
• Server standard out
• Domain log file

62.What is the user of Network channels in Weblogic?

Adds flexibility to the networking configuration:

• Multiple NICs for a single WLS server
• Specific NICs or multiple port numbers on a NIC for specific WLS servers
• Ability to use multiple IP addresses with each server
• Ability to use a single IP address with multiple ports
• Ability to configure the cluster multicast port number independently of the port numbers used by the cluster members
• Multiple SSL configurations on one server

Network channels:

• Define the set of basic attributes of a network connection to WLS
• Can assign multiple channels to a single server (segment network traffic)
• Can prioritize internal (non-URL) connections
• Can separate incoming client traffic from internal server to server traffic in a domain
• A “default” channel gets generated when a server is created.

63.How will you configure a web application in Weblogic?

Web applications are configured using the web.xml and weblogic.xml deployment descriptors, which:

• Define the run-time environment
• Map URLs to servlets and JSPs
• Define application defaults such as welcome and error pages
• Specify J2EE security constraints
• Define work managers for applications
• Set the context root for the application

64.What information will be available in “web.xml” file?

The web.xml file is a deployment descriptor that is used to configure the following:

§                   Servlets and JSP registration

§                   Servlet initialization parameters

§                   JSP tag libraries

§                   MIME type mappings

§                   Welcome file list

§                   Error pages

§                   Security constraints and roles

§                   Resources

§                   EJB references

65.What information will be available in “weblogic.xml” file?

Using weblogic.xml, you can configure the following:

§                   The application’s root context path

§                   Application logging

§                   Security role mappings

§                   Advanced session settings

§                   Session clustering

§                   References to shared libraries

§                   References to server resources (data sources, EJBs, and so on)

§                   Work managers and threading

§                   Virtual directories

§                   JSP compiler options

66.To configure a “web service” Applications in Weblogic, what are all the files required as a deployment descriptor?

A Web service application:

§                   Responds to HTTP client requests using the Simple Object Access Protocol (SOAP)

§                   Uses the same structure as a Java EE Web application

§                   Supports two additional deployment descriptors:

§                        webservices.xml

§                        weblogic-webservices.xml

67. What is the Virtual directory Mappings? Which file you are going to provide these virtual directory mappings?

Virtual directories:

§                   Can be used to refer to physical directories

§                   Enable you to avoid the need to hard code paths to physical directories

§                   Allow multiple Web applications to share common physical directories for specific requests such as images

§                   Decrease duplication of files across applications

§                   Are configured in weblogic.xml

Example:
<virtual-directory-mapping> 
   <local-path>c:/usr/gifs</local-path> 
     <url-pattern>/images/*</url-pattern> 
     <url-pattern>*.jpg</url-pattern> 
</virtual-directory-mapping> 
<virtual-directory-mapping> 
     <local-path>c:/usr/common_jsps.jar</local-path> 
     <url-pattern>*.jsp</url-pattern> 
</virtual-directory-mapping> 

68.What is the deployment descriptor file for ejb applications? What are all the information is going to provide in that file?

Ejb application deployment descriptor file in Weblogic is “weblogic-ejb-jar.xml”. 
Using weblogic-ejb-jar.xml, you can configure the following:

§                   Security role mappings

§                   Advanced security settings

§                   EJB clustering

§                   EJB pooling and caching

§                   Work managers and threading

69.What is an Enterprise Application?

§                   An enterprise application is a grouping of several resources into one deployable unit that is packaged in an .ear file.

§                   These resources include:

§                        Web applications (.war)

§                        EJB applications (.jar)

§                        Java applications (.jar)

§                        Resource adapters (.rar)

70.What is the user of Enterprise Applications?

Use enterprise applications to:

§                   Avoid namespace clashes

§                   Declare application wide security roles

§                   Deploy an application as one unit

§                   Share application wide EJB resources

§                   Configure local JDBC data sources

§                   Configure local JMS resources

§                   Configure local XML resources

71.What is the user of “weblogic-application.xml” deployment descriptor file?

Using weblogic-application.xml, you can configure:

• References to shared libraries
• Work managers and threading
• Default EJB and Web application parameter values

We can configure enterprise wide WLS-specific features with the weblogic-application.xml deployment descriptor:

• XML parsers
• XML entity mappings
• JDBC data sources
• JMS connection factories and destinations
• Security realms

72.What is the user of Weblogic shared java EE Libraries?

A Shared Java EE library:

• Is a reusable portion of a Web or enterprise application
• Is referenced by other deployed applications
• Avoids duplicating source files among Java EE projects
• Can contain deployment descriptors that are merged with the application’s descriptors

73.Explain about deployment methods in Weblogic?

• WLS supports three deployment methods:
• Auto-deployment
• Console deployment
• Command-line deployment
• You can deploy:
• Enterprise, Web, and EJB applications
• Web services
• J2EE libraries
• JDBC, JMS, and Diagnostic Framework modules
• Resource adapters
• Optional packages
• Client application archives
• Applications and EJBs can be deployed:
• In an archived file (.ear, .war, .jar)
• In an exploded (open) directory format

74.How many ways we can deploy an application to Weblogic servers?

Several methods are available to deploy the Oracle WebLogic Server applications and shared libraries, including:

• Administration Console
• WebLogic Scripting Tool (WLST)
• weblogic.Deployer Java class
• wldeploy Ant task
• Auto-deployment folder

75.Explain about auto deployment in Weblogic?

If Production Mode is OFF:

• You can install an application simply by copying it (manually or using the console) to the “autodeploy” 
  directory of the domain
• The Administration Server monitors this directory for new, changed, or removed applications
• This configures, targets, and deploys the application only to the Administration Server
• Location of Applications Directory:
• $BEA_HOME/user_projects/domains/domain_name/autodeploy

76.Explain about FastSwap and On-Demand Deployment in Weblogic?

• WebLogic’s FastSwap feature is:
• Enabled using the WebLogic deployment descriptors
• Available only if the domain is not running in production mode
• Applicable only to Web applications that are not archived
• When enabled:
• WebLogic automatically reloads the modified Java class files within applications
• Developers can perform iterative development without an explicit redeployment
• On-demand deployment:

Excerpt from weblogic.xml:
<fast-swap>true</fast-swap>

77.While deploying an application to Weblogic, what is the difference between Development and Production Mode?

• An Administration Server starts using either:
• The development mode, which turns auto-deployment on
• The production mode, which turns auto-deployment off
• The Administration Server starts in the mode selected at domain creation time.
• The mode is set for all Oracle WebLogic Servers in a given domain.

78.Explain about console deployment method?

Deploying with the console allows full administrator control:

• Installation from a location of your choice
• Manual configuration of application name
• Targeting of application to individual servers and/or clusters
• Configuring the application without targeting it
• Activating deployment when desired

79.Explain about command line deployment?

• The weblogic.Deployer utility allows you to perform deployment operations similar to those available in the console.
• weblogic.Deployer actions can also be scripted with the Ant task wldeploy.

    weblogic.Deployer Syntax:

        % java weblogic.Deployer [options] 

          -deploy|-undeploy|-redeploy|-start|-stop|-listapps] [file(s)] 

    Prepare and deploy a new application: 

         java weblogic.Deployer -adminurl t3://adminserver:7001 

         -username myuser –password mypass –name HRServices

         -source /usr/HRServices.ear -targets serverA –deploy

   Redeploy an application: 

            java weblogic.Deployer -adminurl t3://adminserver:7001 

            -username myuser –password mypass –name HRServices

   redeploy

   Undeploy an application: 

           java weblogic.Deployer -adminurl t3://adminserver:7001 

           -username myuser –password mypass –name HRServices

  undeploy 

  List all applications: 

                java weblogic.Deployer -adminurl t3://adminserver:7001 

                 -username myuser –password mypass -listapps 

80.What is JNDI?

• The Java Naming and Directory Interface is an API for uniformly accessing the different naming and directory services.
• This is a major step forward because:
• Different services use vastly different naming schemes
• Java applications can now navigate seamlessly across databases, files, directories, objects, and networks