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WebLogic Adminstration Interview Questions - 1

Q: What do you mean by weighted based server instance? How do you configure it?

Ans: The Weblogic Servers in the clustered environment could be routed in 6 ways ROUND-ROBIN, WEIGHT-BASED, RANDOM and same algorithms with Affinity. Weight is defined as the number of the requests incoming to a managed server that is default 100. As per the machine capacity and Operating environments will make you to deside how much weight is suggested on that managed server. We can control the incoming requests using weights increase or decrease, So, this way we can route all the request to one of the managed server in the Cluster. This Weight differences can be used when there is operating environment differences are there.

Q: How to enable EJB available to servlet? asume servlet on apache, ejb on Weblogic cluster.

Ans:Any external access to EJB is not allowed. if the apache webserver already configure as front-end. then we need to look up by JNDI tree.

Q: What is the silent mode installation file contains root element? When do you require this mode of installation?

Ans:The root element in silent.xml is <install>This kind of mode usually required in two different situations.

Situation1 : Weblogic clusters could be installed/implemented only on homogenous environments. If cluster1 is constructed with MgdServer1, MgdServer2if one server isusing Weblogic 7 environment and other one on Weblogic 8.1 or higher this is not allowed.

Situation 2: When one huge project is migrated from one physical location to other, Where the Application specialist must have the similar environment as the Production Server had. To prepare Development work with similar kind environment we shall install on First system same as Production Server rest of the developers systems could be installed with silent mode.

Q: What are the basic configuraiton requirements for a Cluster? or
Why do you need multicast address in Clustering?

Ans: The Multicast address is must for clustering, If server instance need to join the cluster it will use multicast address. The Administrator server handles the web/resource request which is incoming to the Weblogic server then the admin server will send poll messages for availability to handle the current incoming request by which member server in the cluster with multicasting. The multicast address should not conflict with the Network configurations on every member server. The range of multicast IP address is : to admin server sends a TTL (Time to Leave) packet,which will acknowledges the readiness of a managed server. If more than one member server is available then it will choose the member server with first come first server bases.

Q: What are all the ANT command options?

Ans:To view all options of ant command is simple, just use the following command :
prompt> ant -help
Note: This will work on Unix and Windows too iff PATH is pointing to ant specific jars

Q: What is the ANT version last you used? How to get it??

Ans: I am using Weblogic 8.1 it internally provides ant support which is 1.5.6 version.To get this simply use :
 prompt> ant -version

Q: How do you config eclipse with Weblogic? Widgets

Ans:Weblogic version wise plug-ins are available for free download sites. Eg: lomboz tool it is a very simple tool, my experience is that deployment on WL is very few steps required.Just we need to copy the plug-in extracted to eclipse/plug-ins folder. Here we need to follow the correct J2EE specification for easy deployments of application.

Q: what is the source to identifying the Connection pool failure? What is the remedy?

Ans: In WL 7/8 to identify the Connection pool failure we have 3 options:
1.The Connection pool hosting Server instance healthchecking by Monitoring tab where we need to find the idle thread availability.2. Checking in the weblogic log of that corresponding server instance. Usually we get broken pipe Exception.This could be generated due to overload on connection pool. To resolve we can tune the execute threads for the corresponding server instance.3. Look for Thread dump and identify the which thread is doing which task execution?

Q: What is Thread Dump? Why we need it? How do we get it?

Ans:Thread dump concept is used only by Admin users who operates the production server; it is the dump of the behavior of the WebLogic server instance’s execute threads.When the thread dumps helpful? If WLS execute threads misbehaving due to following reasonsMaybe you just need more threads. Maybe you need some of your application to use a different queue. Maybe your application needs tuning.There is a need of trouble shoots the issues due to various reasons:
1. Requests overloaded
2. Connection Pool fails
3. File cannot read/write for any application (which might be xml file too)
4. Queues are overloaded
or back-end legacy connection issues
In windows CTRL + Break , There is another common method to get thread dump:a) Open a cmd window (in Windows) or shell (in Unix/Linux)b) Set the proper java path and add weblogic.jar to the classpathc) Run the following command script :prompt >java weblogic.Admin -url t3://host:port -username weblogic -password weblogic THREAD_DUMP Here please replace with the correct host, port number, username and password. You can get the thread dump from the standard output.
Best WebLogic (JVM ) Thread Dump analyzer are:
1. Samurai
2. Java TDA
3. Thread Dump Viewer
4. Eclipse lock analyzer plugin

Q: What is the procedure for Queues config? How to make them to free?

1. The Queues configuration requires persistence storage which could be a File on operating system or a DataSource.
2. The queue configuration requires JMSConnectionFactory, JMSServer, jms module Queue or topic as per the application need
You can created using the Weblogic Administration console or using WLST in latest versions 9.x onwards.