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WebLogic Administrator interview Questions 3


 
 
1.  Can you give the  deployer utility syntax?
The syntax goes like this:
$  java weblogic.Deployer -adminurl http://admin:7001 -name appName -source /myapp/appName.ear -targets [serverList] [-activate or other options]

2. How do you install Apache web server in UNIX and windows?

You will get a binaries for Apache website and you compile and build with the 4 steps
a. Extract the compressed file
b. Execute configure.sh file from the extracted folder
c. make
d. make install

http://wlabypani.blogspot.com/2009/11/apache-installation-configuaration.html

3  What is Oracle SID in Database?

It is a  Service ID in Oracle database, that we need to use in configuring JDBC Connection pool.

4. What is listener in database?

In Oracle listener is that which is associated with a SID and host, port. It is configured in the tnsnames.ora file. You can verify it by tnsping command.

5. What are the tuning techniques you applied?
Tunning for JVM - chanigng -Xmx, -Xms, MaxNewSize, MaxPermSize, and if required GC algorithms
Tuning in Threads/ThreadPool -- Defining Workmanager with maximum constraint
Tuning TCP/IP connections Interface address, backlog count,
Tuing  JMS  -- changing queue sizes as required

Tuing JDBC - initial count, maximum capacity, increase by number of connections

 
6. How do you troubleshoot if config.xml file will be deleted

First we look for is there any last good backup of configuration is availble on the Admin machine. If it is not found then alternatively you can find it on remote machines where the managed servers running.
 
Best practice is whenever there is a configuration changes made before and after you need to take a backup.That will help you such situation where you might need old configuration sometime.

7.  How do u trouble shoot if managed server is in FAILED state?
If any managed server is in FAILED state there could be reasons as follows:
i) deployment failed
ii) JDBC DataSource issue
iii) JMS configuration issue

8. How to monitor webLogic using WLST?
First you need to connect to the adminServer. then you can use any Runtime MBean.
Using WLST we can monitor various Runtime MBeans such as ThreadPool, JVM, JDBC ConnectionPool, JMS Server and Server Life Cycle for state of a WebLogic server instance.

9.  Can you explain about bea guardian?
Gaurdian is only helpful when you have GUI. It is enables that all new patches available on Oracle site can shown in the right downside corner shows.

10.What are monitoring tools you know?
There are wide varieties of  monitoring tools available, such as:
a. HP-OVO
b. Introscope Willey
c. Patrol
d. Mercury and many more...
 
11.  What are the difference between Connection pool and data source?
ConnectionPool is physically connects to the Database. where as Data Source is a logical resource that can be used by developer or any other resource for accessing Connection of pools.
DataSource can be associated with JNDI name that is used for lookup from from any other client.
 
12.  What are the difference in WebLogic 8.1 and 9.x?
Side by side deployment introduced in WL 9.x
deployment descriptors
JDK support 1.4 and 1.5 respectivly
console Look and feel changed Cuncurrent access is controlled with Change center 'Lock and Edit' , 'Activate Changes', 'Undo All chnages' buttons.
ConnectionPool is included in DataSource configuration part.
JMS Uniform distributed destination is reduced configuration side.
JMX version change 1.2 so the MBean accessing methods simplified.
 
13. What is JMS and how do you configure it?
Java Messaging System it is a API supported by J2EE application server for messaging between diffent resources. it can be used by MDB (Message Driven Beans).  First you need to configure JMS System resource,  JMS module consists  any one out of  PTP,   publisher/Subscriber type

14. What is cluster and how do you configure?
Cluster is a group of managed servers.
Using console
Usning WLST
You need to provide the Multicast address, Multicast port, Cluster Address which is nothing but the listen addresses, listen port of all managed servers need to group together.

15.  What is the use of multicast address?
In a WebLogic domain to broadcast the heart beat message to all cluster members. TTL will be send to the multicast address, to this address all the cluster members are subscribers. If one of the Server crashes that can be notified by all other members by missing 3 times heart -beat. So that secondary server will takeover the request and start working with the replication data.

16. How to get thread dump and what the purpose of stuck thread?
Get the java process id, you can get it by jps or customized script for it.
kill -3 pid for unix env.
Ctrl+break for windows env.
When there is a Stuck Thread need to monitor the log for few minutes some times 2 or 3 stuck threads hogging but after sometime it will be  unstucked. If you take multiple thread dump for every 5 sec gap and analyse with sumarai or Java Thread Analyzer tool you will get to know why it is stuck what is causing the instances to mis behave that time.

17.  What is nmenroll in WLST?

The nmEnroll() method is used for enroll the machine with the weblogic domains running on that. It is name and its path.
the Nodemanager always get the domain information from the Administration server provided that it should have enrolled in that machine.

18.    Tell about ant scripts?
You can ANT Scripts are mostly used for deployment process in development environtments.
 
ANT can be used to
  1. start WebLogic Server
  2. deploy the application
  3. Configure a single WebLogic server
  4. invoking WLST script
19. Types of load balancing techniques and differences b/n them
There are Hardware loadblancer, Software loadbalancer BIG IP F5 is most leading load balancers in use.
Again the Software loadbalancing CMS, CSS Context Switch Servicing
Basically Load balances uses Round robin method to its connecting Webservers.
 
Plrease ref wikipedia.com for more details.

20. What is the important configuration file in apache?
The Apache configuration will be defined in the httpd.conf, if required segrigated weblogic.conf file can be created.
SSL enable sites requires httpsd.conf

21. How do you provide load balancing?
In WebLogic Cluster side we have 3 basic types and each supports Affinity based also.
I) Round Robin
ii) Random
iii) Weight based

22. Why Data source is not there in Weblogic 9?

I just wonder about this question!! It is there under jdbc link

23.    When do you use vi editor?

In UNIX environments we have vi editor for creating new file which can be shell or python or jython or plain file.
I - insert mode
Esc - to come out of the mode
r - replace char
a - append to the line
O - insert above line
o - insert below line
dw - delete word
dd - delete line
x - delete char
/ - search a pattern
:set nu setup numbers  etc...

24.  What type of shell scripts you have created?
There are many bash scripts whihc I had developed
i) Finding a pattern in all log files.
ii) instance name assciated with PID
iii) Heap dump
iv) Multiple copy for produciton Code move
v) Many DB related scripts
vi) Log archiving scripts
vii) Daily DTS Collector scripts

25. What type of wlst scripts u have created?
WLST scripts
I) Thread Monitoring script
ii) JVM monitoring
iii) JMS monitoring
iv) DataSource monitoring
v) Site wise, Server wise, Domain wise scripts


26. How to test the port is existing or not in unix?
On the UNIX you can give the following command
netstat -na |grep <port>
Interview happen at NESS Technologies, India 2009
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