Weblogic Interview Question Answers
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1. What is Weblogic?
Answer: WebLogic Server is an application server platform to Grow and Install multitier distributed enterprise applications. This Server Concentrates on application services like Web server functionality, business components, and access to backend enterprise systems. It uses technologies like caching and connection pooling to enhance resource use and application performance. It also provides enterprise-level security and Administration facilities.
2. How do you troubleshoot Server Hang?
Answer: We can use java WebLogic.Admin PING to see if we get a traditional response.
We need to require multiple thread dumps with kill -3 PID on Unix and CTLR Break on Windows.
Analyze the thread dump to seek out the basis cause.
3. What is Node Manager?
Answer: Node Manager could also be a program that’s used to control WebLogic Server instances. On the one Node here the
Manager Work is to manage all of the server running on a uniform machine or different machine.
These instances can reside in several clusters, domains, and such. you would like to configure each machine in
your domain to talk with Node Manager.
4. How to change from development mode to production mode in Weblogic 10.3?
Answer: To change Weblogic start-up mode from Developer to production. a way to vary it’s simply
editing set DomainEnv.cmd which resides in $root_domain/bin folder.
Look for the road that sets the PRODUCTION_MODE script variable: set PRODUCTION_MODE
Add false to the worth of the PRODUCTION_MODE variable to make sure the server starts in development
Set true for starting in prod mode.
set PRODUCTION_MODE=false
Save your changes and exit the text editor.
5. Why is there no polymorphic-type response from a create () or find () method?
Answer: The EJB Specification prohibits this type of action and then the WebLogic.bc compiler checks for this Working Condition and prohibits any polymorphic sort of response from a create() or find() method.
The reason they create() and find() methods aren’t polymorphic is analogous to the rationale constructors aren’t polymorphic in Java. The derived classes generally don’t know or cannot initialize the bottom class properly.
6. Why did my JDBC code throw a rollback SQL Exception?
Answer: JDBC code may throw the next exception:
The coordinator has rolled back the transaction. No further JDBC is allowed within the transaction.
The WebLogic JTS JDBC driver throws this exception when this JDBC connection transaction rolls back before or during the JDBC call. This Irregularity indicates that the transaction during the JDBC connection was participating was rolled back at some point before or during the JDBC call.
The rollback may have happened in an earlier EJB invoke that was a neighborhood of the transaction, or the rollback may have occurred because the transaction timed out. In either case, the transaction are getting to be rolled back, the connection returned to the pool and thus the database resources released. to travel Front , the JTS JDBC connection must be closed and it must be Re-opened during a replacement transaction .
7. Inclined to create a profession as Oracle WebLogic Developer?
Answer: Then here is that the blog post on Oracle WebLogic Training.
When Utilize a resource adapter (.rar) to WebLogic Server .
8. classes placed within the WebLogic classpath?
Answer: as an example , i’m deploying an EJB and a resource adapter (.rar), the EJB has no dependencies on the .rar because the EJB is writing to the common client interface (CCI). The EJB app sends/marshals as parameter classes that are Explained within the .rar. for a few reason, the EJB’s classloader cannot find the definition of this .rar-specific class, albeit the .rar is deploying successfully. I receive the subsequent error on the EJB client
:java.rmi.UnmarshalException: error unmarshalling arguments;
nested exception is:
java.lang.Class Not Found Exception:
com.mycompany.InteractionSpecImpl
9. How Do Stubs Function Inside Weblogic Server Cluster At The Time Of Failure?
Answer: Stubs perform the removing the failed instance from the list whenever it got failed. The stub usually makes use of DNS for locating the running server and also for obtaining the list of the instances that are currently available with the appliance . The list which is available of the instances with the server inside cluster gets periodically refreshment and allows in acquiring advantages related to new servers. the benefits are gained because the server gets added to the cluster.
10. What are the applications in Websphere?
Answer: WebSphere applications use the subsequent sorts of technologies:
Java describing and other standards for developing applications.WebSphere programming model extensions to reinforce application functionality.
Containers and services within the appliance server, employed by deployed applications, and which sometimes are often extended.
11. What are Weblogic clusters?
Answer: In common WebLogic Server consists of Different server instances which are running simultaneously and which deals together to provide increased scalability and reliability.A cluster appears to clients to be one WebLogic Server instance. The server Illustration that has a cluster can run on an equivalent machine, or be located on different machines. you’ll increase a cluster’s capacity by adding additional server instances to the cluster on an existing machine, otherwise you can add machines to the cluster to host the incremental server instances. Each server instance during a cluster must run an equivalent version of WebLogic Server.
Benefits of clustering:
Scalability:
The capacity of an application deployed on a WebLogic Server cluster are often increased dynamically to satisfy demand. you’ll add server instances to a cluster without interruption of service, the appliance continues to run without impact to clients and end-users.
High-Availability:
In This Server cluster, application process can continue when a server Goes Wrong. You “cluster” application components by situating them on the multiple server instances within the cluster, so, if a server instance on which a component is running fails, another server instance on which that the component is deployed can continue application working .
12. What sort of object is returned by ResultSet.getObject()?
Answer: WebLogic driver for Oracle always returns a Java object that preserves the precision of the info retrieved. WebLogic driver for Oracle returns the subsequent from the getObject() method:
For columns of types NUMBER(n) and NUMBER(m,n): a Double is returned if the defined precision of the column are often represented by a Double; otherwise, BigDecimal is returned.
For columns of type NUMBER: Because there’s no explicit precision, the Java type to return is decided supported the particular value in each row, and this might vary from row to row. An Integer is returned if the worth features a zero-valued fractional component and therefore the value are often represented by an integer.
For example, 1.0000 are going to be an integer. an extended is returned for a worth like 123456789123.00000. If a worth features a non-zero fractional component, a Double is returned if the precision of the worth are often represented by a Double; otherwise, a BigDecimal is returned.
13. How do I call Oracle stored procedures that take no parameters?
Answer:
Here is what we use that works:
CallableStatement cstmt = conn.prepare all(“Begin to proclaim;
END;”);
cstmt.execute();
where the program is that the name of an Oracle stored procedure. this is often standard Oracle SQL syntax that works with any Oracle DBMS. you would possibly also use the subsequent syntax:
CallableStatement cstmt = conn.prepare all(“{call procName};”);
cstmt.execute();
So this code, Confirm you that to the Java Extended SQL spec, will work with any type of DBMS, not just Oracle.
14. State a number of the features present in Websphere?
Answer:
Supports the Servlet/JSP container where it runs on top of HTTP.
Supports HTTP servers like IBM HTTP server, MS IIS and Netscape iPlanet server.
Supports HTML pages, Setvlets, Java Server Pages and XML.
Supports EJB component model, Workload Management. WLM supports multiple servers within one administrative domain.
15. What are the varied causes for OUT OF MEMORY?
Answer:
a) Insufficient heap size, unable to match the additional load.
b) Objects lying too long, like HTTP Sessions.
c) Memory leak in application code.
d) Full GC not happening thanks to JVM Bug.
16. what percentage thanks to Start And Stop Weblogic Servers?
Answer:
There are some ways to start out & stop WebLogic Admin and managed servers:
1) Script
2) “Java Weblogic.server “command(The weblogic.Server class is that the main class for a WebLogic Server instance)
3) From startup option on windows
4) WLST with or without node manager
You can start managed servers using :
1) scripts
2) admin console
3) using WLST
4) using node manager
5) Java WebLogic.server command
17. What is the way to Know Weblogic Version?
Answer: Within the WebLogic console, within the left navigation tree, click on “Environment”, then “Servers”. Then click on one among the servers within the list. Then click on the “Monitoring” tab. check out the “WebLogic Version” field. (weblogic interview question answers )
18. Explain Deployment Descriptors?
Answer: Deployment descriptors are related to most the modules also as applications. The deployment descriptors are often seen within the sort of XML documents and that they are capable of describing the contents that are a part of the directory or the jar file. J2EE specifications usually define the quality also because the deployment descriptors which are portable for J2EE applications and modules.
19. what’s The Name Of Default Jvm that’s Made Used For Weblogic?
Answer: The sun hotspot JDK default is formed used for development, JRockit is that the one used for the assembly of WebLogic 11g also as 12c. The OS is another factor that helps in choosing the certified JDK JVM.
20. what’s Thread dump?
Answer:
Thread Dump may be a textual dump of all active threads and monitors of Java apps running during a
Virtual Machine.
21. what’s the Managed Server?
Answer: A managed server may be a server during a domain that’s not the Administration server. It contacts the
administration server for configuration information. It runs a business application during a production
environment. it’s independent of all other Managed servers during a domain (unless they’re not during a cluster).
You can have many managed servers during a domain.
22. Explain the attribute CHANNEL in WebSphere MQ?
Answer: A channel may be a connection that’s to determine a link between a sending channel and receiving channel. A channel features a sender channel at the local queue manager and receiver channel at the remote queue manager. These two channels contains an equivalent name and together make one channel.
This is Combined with WebSphere MQ applications, to Direct the channels for receiving and sending messages during a file that defines sender and receiver channels.
23. what’s the difference between Multicast and Unicast?
Answer: Unicast is that the method utilized in the clustering technique where there’s cluster master and every server should ping to the present cluster master for informing that the server is alive.
Multicast: it’s a sort of clustering system where there’s no cluster master and each and every server must ping one another for informing their existence. Multicasting has many messages to be sent within the sort of ping as each server must inform all others about its existence. This condition creates much complexity related to the tactic compared to unicast.
24. what’s the difference between WebLogic and WebSphere?
Answer: Though the functionality of those two products is closer, there are minor differences within the standards that support. These differences are:
WebSphere’s focus is on connectivity, integration and web services .
WebLogic’s focus is on emerging standards and ease-of-use of J2EE.
WebSphere’s performance is best in terms of implementations of J2EE is small more involved, and supports more integration and transaction management
WebSphere strictly follows J2EE architecture.
25. How to troubleshoot and overcome such issues?
Answer:
Gather memory data by enabling GC verbose.
If its thanks to Http Session, timing out https session after certain interval might help.
Look into the code for JDBC connection handling.
Optimizing the heap size consistent with the load.
26. How to troubleshoot it?
Answer:
In a Solaris environment, we’d like to require pstack and prestack and see what the threads do .
In Windows, we’d like to use pslist and process explorer.
27. what’s Clustering and what’s achieved through it?
Answer:
Clustering is that the grouping together of servers for the aim of high availability and scalability.
Load balancing and Failover is achieved.
28. what’s the difference between Development mode and Production mode of Weblogic Server?
Answer:
Development Mode:
1. Sun Hotspot is the the default JDK for the development domain .
2. you’ll use the demo certificates for SSL.
3. Auto deployment(to admin server only) is enabled.
4. At Start-up Server Occurences rotate their log files .
5. During start-up Admin Server uses an automatically created boot.properties .
6. 15 is the default maximum capacity for JDBC Datasource .
7. The debug flag which is employed to start out the WebLogic Workshop Debugger is enabled.
8. In Development Mode any configuration change is completed by a user doesn’t need him to require a Lock and Edit session.
9. Availability of web service test client.
10. The Username and password for Node manager – Default Admin credentials.
11. Availability of Classloader Analysis Tool: Yes.
12. The default start parameters when using Sun JDK and therefore the default start
Production Mode:
1. JRockit is the default JDK for production domain .
2. If you employ the demo certificates for SSL a warning is displayed.
3. Auto deployment ( It is prefered only to admin server ) is off Condition .
4. when it reaches to 5MB Server instances rotate their log files .
5. During start-up Server prompts for username and password .
6. 25 is the default maximum capacity for JDBC Datasource .
7. The debug flag which is employed to start out the WebLogic Workshop Debugger is disabled.
8. In Production Mode the user must procure a Lock and Edit session before trying to form any configurational changes.
9. No Availability of web service test client.
10. Node manager username and password: Randomly generated
11. Availability of Classloader Analysis Tool: No.
29. What are deployment descriptors?
Answer: XML documents—Which define the contents of the directory or JAR file. Deployment descriptors are simply stated as text documents which are formatted with XML tags. The J2EE specifications define a typical , portable deployment descriptors for J2EE modules and applications.
30. what’s the default JVM used for Weblogic?
Answer: JRockit is for Production mode for WebLogic 11g and 12c. Operating environment is also One factor to pick the Certified JDK JVM. If you would like to vary you would like to specify it. Sun Hotspot JDK default for Development installation .
31. what’s a website template?
Answer: A website template may be a jar file default one is wls.jar file, which is ‘/bea/weblogic81/common/templates/domains/, it’s all the features that are required for the quality WebLogic domain, we will even create domain template of our own configuration. by this template, we mustn’t configure whenever we create a replacement domain.
By employing a template, we can
Create servers
Clusters
Machines
Configure services like JMS, JDBC, Applications
32. what percentage ways take Thread Dumps?
Answer: we’ve to require a Thread dumps repeatedly once we faced issues. we will choose one Procedure. For analyzing take dumps some Intervals.
33. How am i able to use ANT to run a Java application?
Answer:
One example to run Java application using ANT:
<jvmargvalue=”-dname=${name}” 0px; margin: 0px; color: rgb(0, 0, 0); font-family: Helvetica, “Open Sans”, Arial, sans-serif, Verdana; font-size: 15px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px;”>
34. Explain the way to debug my ANT script ?
Answer: The echo are often used because the alert () of the JavaScript.
Use project.log(“msg”) in javascript or custom ant task.
Run ANT with -verbose, or maybe -debug, to urge more information on what it’s doing, and where.
35. what’s J2ME?
Answer:
– J2ME is defined as Java 2 Platform Micro Edition.
– it’s targeted at small, standalone or connectible consumer and embedded devices.
– This technology consists of both a programing language and a software platform.
– it’s a highly optimized version of JRE and consists of JVM and a group of APIs, which is suitable for easy runtime environments.
– It provides a strong and versatile environment for running applications.
36. what’s the CDC?
Answer:
– CDC stands for Connected Device Configuration.
– it’s a group of tools for developing applications that run on a variety of network-connected consumer and embedded devices that support the Java ME CDC application framework.
– it’s a JVM that’s highly optimized for resource-constrained devices.
– it’s used for bigger devices, like set-top box and PDAs.
– CDC Consists of greater memory and high robust network connectivity.
37. what’s CDMA?
Answer:
– CDMA (Code Division Multiple Access) may be a multiplexing technique supported spread spectrum approach.
– this enables several users to share a bandwidth of frequencies.
– during this , a special coding scheme is employed where each transmitter is assigned a code to permit multiple users to be multiplexed over an equivalent physical channel.
– It refers to any several protocols which are utilized in second and third-generation wireless communication.
– It employs analog to digital conversion together with spread spectrum technology.
38. what’s Telematics?
Answer:
– Telematics may be a GPS technology that gives location-based service to trace latitude and longitude of a vehicle.
– The outputs are mounted on dashboards which maps in LED consoles .
– The server is connected to remote processing centers which give data, voice and Internet services.
– Telematics is that the technology of sending, receiving and storing information concerning remote objects, like vehicles, telecommunication devices.
39. How to configure JMS?
Answer:
JMS (Java Message Service) may be a standard API for accessing enterprise messaging systems. Specifically, WebLogic JMS:
It Enables Java applications sharing a messaging system to exchange messages from One Terminal to other .
Simplifies application development by providing a typical interface for creating, sending, and receiving messages.
By Using the Administration Console, you can easily define configuration allocation :
1. Create JMS servers and target a WebLogic Server instance or a Migratable Target where the JMS server are going to be deployed.
2. Create and/or customize values , connection factories, destinations , JMS templates, destination sort order (using destination keys), persistent stores (file or JDBC), paging stores, session pools, and connected consumers.
3. Define message and/or bytes thresholds and quotas, also as a maximum allowable message size on your JMS servers, destinations, and templates.
Enable any desired WebLogic JMS features, such as:
Server clustering using multiple connection factories.
High availability and cargo balancing for destinations across a cluster by using distributed destinations.
Persistent messages and sturdy subscribers
Paging out message bodies during peak load periods to release memory.
The Controlling message flow during peak load periods which also including blocking message producers.
Establishing a message expiration policy to make sure that expired messages are cleaned up immediately.
Preventing the errors which caused by message quota by temporarily blocking message producers from sending messages to a destination when it exceeds its specified maximum message quota.
Concurrent message processing via session pools.
40. What you’ll Do with Node Manager?
Answer:
We can manage the entire gamut of activities from the Node manager
1) You can Start, Shut Down, and Restart an Administration Server
2) You can also Start, Shut Down, Suspend, and Restart Managed Servers
3) Monitor Servers and consider Log Data
41. what’s extended deployment in WebSphere?
Answer:
It delivers features for optimizing IT resources with enhanced Qualities of Service .
The suite comprises of three products:
WebSphere Virtual Enterprise:
It increases flexibility and agility to make sure business process integrity, improve service, application performance, and better manage health.
It provides application infrastructure virtualization capabilities that lower costs required to make , manage, and run enterprise applications and an SOA environment.
WebSphere extreme Scale:
It is an important IBM software technology for conducting extreme transaction processing.
It provides transactional integrity and transparent failover to make sure high availability, high reliability, and constant response times.
It operates as an in-memory data grid that dynamically caches, partitions, replicates, and manages application data and business logic across multiple servers.
Compute Grid:
Enables the scheduling, execution, and monitoring of batch type jobs with enhanced service policy and workload management
42. What are the Admin Default ports?
Answer: The non-SSL listen port for the Administration Server’s default network configuration is 7001 by default.
The SSL listen port for the Administration Server’s default network configuration is 7002 by default.
WebLogic Admin servers and Managed servers could communicate with Admin port which is separate network channel. in order that other communications are often run on different networks.
43. How can default JVM be changed to others?
Answer: For changing the JVM are often done by following the steps below.
1)You should first set the JAVA_HOME within the start script of the server.
2)Change the config.xml of the domain for using the JRockit javac.exe
3) Remove any quite switches specific to Sun JVM from start scripts of the server. ( weblogic interview question answers )
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