Monday, 18 June 2012

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

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