Set 3:- WebLogic Interview Questions & Answers

Question 1: We often see BSU when using weblogic.What is the meaning of BSU ?

Answer : Oracle bought Weblogic from BEA. BSU Stands for Bea Smart Update. This utility is used to apply the WebLogic Server Patches. In simple terms, it is first letter of name of founders Bill Coleman, Ed Scott and Alfred Chuang.

Question 2: What is the easiest way to set the classpath?

Answer : WebLogic Server installs the following script that you can use to set the classpath that a server requires:

WL_HOME\server\bin\setWLSEnv.cmd (on Windows)
WL_HOME/server/bin/setWLSEnv.sh (on UNIX)

where WL_HOME is the directory in which you installed WebLogic Server

Question 3: How to start Node Manager ?

Answer:  $WL_HOME\server\bin\startNodeManager.sh

To Stop Node Manager

In Unix/Linux, kill the process –

kill -9 ps -ef | grep -i nodemanager.javahome | grep -v grep | awk {'print $2'} | head -1

Question 4: Why node manager is required?

Answer : A Node Manager process is not associated with a specific WebLogic domain but with a machine. You can use the same Node Manager process to control server instances in any WebLogic Server domain, as long as the server instances reside on the same machine as the Node Manager process. Node Manager must run on each computer that hosts WebLogic Server instances. whether Administration Server or Managed Server that you want to control with Node Manager.

Question 5: What is the difference between the Sun JVM and BEA JRockit JVM?

Answer : The most well know JVM is the implementation from Sun. The Sun JVM is called HotSpot. The Sun JVM is shipped in the Java Developer’s Kit (JDK) and Java Runtime Environment (JRE) from Sun.

The BEA JRockit JVM from BEA systems is optimized for reliability and performance for server side applications. To achieve this, BEA JRockit JVM uses technologies such as code generation, hot spot detection, code optimization, advanced garbage collection algorithms and tight operating system integration.

Question 6: What are JVM Tuning Parameters.

Answer : If you have a single processor, single thread machine then you should use the serial collector (default for some configurations, can be enabled explicitly for with -XX: +UseSerialGC). For multiprocessor machines where your workload is basically CPU bound, use the parallel collector. This is enabled by default if you use the -server flag, or you can enable it explicitly with -XX:+UseParallelGC. If you’d rather keep the GC pauses shorter at the expense of using more total CPU time for GC, and you have more than one CPU, you can use the concurrent collector (-XX:+UseConcMarkSweepGC).

Question 7: How do you do performance tuning of WLS? What are various areas to do it

Answer : a. Application Tuning - 

• jsp precompilation
• ejb pool size cache..

b. OS Tuning

• Setting tcp ip parameter.
• tcp_time_wait_interval
• tcp_conn_req_max_q

c. Core Server Tuning.

• tune work manager, 
• tune chuck size and chunk pool size, 
• using performance packs, 
• connection backlog buffering.

d. JVM Tuning

• tuning gc strategy,
• monitoring garbage collection..

Question 8: What is HTTP tunneling? How can we configure it on WebLogic?

Answer : HTTP tuning provides a way to simulate a tasteful socket connection between WebLogic Server and a Java client when your only option is to use the HTTP protocol. It is generally used to tunnel through an HTTP port in a security firewall. HTTP is a stateless protocol, but WebLogic Server provides tunneling functionality to make the connection appear to be a regular T3Connection.

Steps to configure Http tunneling.

• Login into the Admin Console, click on the server on which you want to enable he Http Tunneling feature
• Click on the Protocols tab
• General
• check the “Enable Tunneling” check box.

Now you can communicate with the JVMs (Server Instances) using protocols other than t3

Question 9: What is the difference between T3 and HTTP protocol?

Answer : WebLogic uses the T3 protocols for internal and external connections to the servers. The T3 protocol often is used in WebLogic implementation of RMI. Proprietary of WebLogic Server.

Http protocols are used primarily for HTTP communication between the browser and the web server. Standard follows the W3C (World Wide Web Consortium).

Note: All of these protocols are, by default, multiplexed over the same connection to the server’s address and port. So you can access a web page hosted by the server using a URL such as http://host:port/page.jsp. An external client can set up an initial JNDI context to a server using the URL t3://host:port/. All that has changed is the protocol over which the client must communicate with the server.

Question 10: What are the States of the Weblogic Server?

Answer : There are 9 states of server which are given below

• Shutdown
• Starting
• Standby
• Resuming
• Running
• Suspending
• Shutting down
• Failed
• Unknown

Question 11: How to access admin console ?

Answer : ssl enabled admin console accessed as :

Example – https://localhost:7001/console

non ssl admin console accessed as :

Example – http://localhost:7001/console


Question 12: What is boot.properties file ? what is the significance of it

Answer : boot.properties is the file used by admin or managed server during startup for username and password. it exist under your domain/servers/server_name/security folder.

When you create a domain in development mode then it creates automatically during startup of admin server but if you create a domain in production mode then you need to define it explicitly otherwise on every reboot of admin server it will prompt you for username and password.

So in production mode –

Start admin server by manually passing the username and password

stop it ( press cntrl+c on the started session )

go to your domain/servers/your_admin_server/ create a folder “security”

go inside security and create a file “boot.properties” with below contents

username=your_admin_username

password=your_admin_password

now start the admin server, it will not prompt you for username & password further.

If you are going to start your managed servers from admin console then no need to create this file for managed server but if you are going to start managed servers via startManagedweblogic script then you need to follow the same above procedure for each managed server.

Question 13: What is actually WebLogic Cache?

Answer: Basically all the web-tier related files (.jsp .class, JSPCompiled files etc.,) get stored in some directory. This is treated as cache whenever there is restart of a WebLogic instance happen then the WebLogic server will look-up for last serviced object status stored in the cache to service for any pending requests. Usually, when your EJB Classes need sessions, JMS object requires persistance, your web-tier may contain static contents then Cache will be used by WebLogic Application Server instance.

Question 14: Why we need to remove Cache?

Answer: Whenever your application is accessed for the first time that fresh deployment of a new version, WebLogic server lookup in this directory, if there are older objects persists that will be conflict with new code objects. This is where the need of removal of cache arises.Where there is a need of new version deployment we might need to clear the cache when the changes to the new version is not reflected.

Generally for WebLogic 9.x and higher versions

WIN: C:\weblogic\user_projects\domains\yourdomain\servers\yourserver\tmp
UNIX: /weblogic/user_projects/domains/yourdomain/servers/yourserver/tmp

you can use the following commands to clear the cache:

WIN: rd C:\weblogic\user_projects\domains\yourdomain\servers\yourserver\tmp
UNIX: rm -rf /weblogic/user_projects/domains/yourdomain/servers/yourserver/tmp

Here I am removing all the subdirectories and files in the the given directory.

Question 15: When we will take Thread dump? Please give us some examples

Answer : Some of the examples would be

1. when server is hang Position, i.e. that time server will not respond to coming requests.
2. While sever is taking more time to restart
3. When we are Getting exception like “java.lang.OutOfMemoryException”
4. Process running out of File descriptors. Server cannot accept further requests because sockets cannot be created
5. Infinite Looping in the code

Question 16: How many ways take Thread Dumps?

Answer : we have to take a Thread dumps many times when we faced issues. We can choose one Procedure. For analyzing take dumps some Intervals (like every 20mins, 5mins etc.).

Question 17: What you Can Do with Node Manager

Answer : We can manage the whole gamut of activities from Node manager

1) Start, Shut Down, and Restart an Administration Server
2) Start, Shut Down, Suspend, and Restart Managed Servers
3) Monitor Servers and View Log Data

Question 18: We see error like 404 and 500. What does they mean?

Answer: The error code 404 – Page not found this says there is no page on the server when browser client requesting, this can happen when application is not deployed properly or not in active state or not initialized properly

500- Internal server error This error occurs when there is a communication issue between server’s intermediate services

Question 19: What is the difference between stage and no stage deployment?

Answer : Stage Deployment:- Admin server Having the physical copy and it will distribute to remaining instances.

Staged deployment will copy your deployment units onto the deployment servers, place them into the $WL_HOME/servers/SERVER_NAME/stage directory and deploy them from there.

In no-stage mode, the Administration Server does not copy the archive files from their source location. Instead, each target server must access the archive files from a single source directory for deployment. The staging directory of target servers is ignored for no-stage deployments.

Question 20: how to Check the version of java in Unix ?

Answer : java -version run this command in linux to know the java version.