List of Weblogic Interview Questions and Answers
Commonly asked Weblogic Interview Questions and Answers are as follows
Q1. What is Weblogic?
WebLogic is a J2EE application server and also an HTTP web server by Oracle, for Unix, Linux, Microsoft Windows, and other platforms. WebLogic supports Oracle, DB2, Microsoft SQL Server, and other JDBC-compliant databases.
WebLogic Server is an application server: a platform for developing and deploying multitier distributed enterprise applications. WebLogic Server centralizes application services such as Web server functionality, business components, and access to backend enterprise systems.
Q2. What are the Basic Components of Weblogic Server?
These are the basic weblogic components
- Admin Server
- Managed Server
- Node Manager
- Weblogic Server Cluster
Q3. What is the Domain in Weblogic server?
- The domain is a logically related group of Oracle WebLogic Server resources that are managed as a single unit.
- Domain Provides one point of administration
- Can logically separate: Development, test, and production applications and Organizational divisions
Q4. What is the server?
A server is an instance of WebLogic. Server executing in a Java Virtual Machine ().
1) Runs on a designated Oracle WebLogic Server machine
2) Has a dedicated amount of RAM
3) Is multithreaded
Two types of servers:
1) Administration Server
2) Managed Server
Q5. What is the Admin Server ?
Admin Server is the central domain configuration interface which is used to create, delete and configure the resources of a domain like managed server, machine, cluster, data source, work managers etc.
Q6. What is the Managed Server?
A managed server is a server in a domain that is not the Administration server. It contacts the administration server for configuration information. It runs the business application in a production environment. It is independent of all other Managed servers in a domain (unless they are not in a cluster). You can have many managed servers in a domain. Individual managed servers are typically added for capacity and application isolation.
Q7. How Administration server and Managed servers will interact?
The Administration Server stores the master copy of the domain configuration, including the configuration for all Managed Servers in the domain. Each Managed Server stores a local copy of the domain configuration file. When a Managed Server starts, it connects to the Administration Server to synchronize the configuration. When the configuration is changed, the Administration Server sends the changed configuration to the Managed Servers.
Q8. What is the MSI mode in Weblogic? How can you enable and disable this option?
MSI is nothing but Managed Server Independence. By default, Managed Servers can function independently of the Administration Server. A Managed Server instance can start in MSI mode if the Administration Server is unavailable. Configure MSI mode from the Administration Console.
To start a Managed Server in MSI mode, perform the following:
Ensure that the Managed Server’s root directory contains the config subdirectory. If the config subdirectory does not exist, copy it from the Administration Server’s root directory.
Start the Managed Server at the command line or by using a script.
Environment > Servers > Server_Name > Tuning > Advanced > Managed Server Independence Enabled check box
for more info check here
Q9. Difference between Weblogic Development and Production Mode?
Here are some difference between Weblogic Development Mode and Production Mode:
1) The default JDK for development domain is Sun Hotspot
2) You can use the demo certificates for SSL
3) Auto deployment is enabled
4) Server instances rotate their log files on startup
5) Admin Server uses an automatically created boot.properties during startup
6) The default maximum capacity for JDBC Datasource is 15
1) The default JDK for production domain is JRockit
2) If you use the demo certificates for SSL a warning is displayed
3) Auto deployment is disabled
4) Server instances rotate their log files when it reaches 5MB
5) Admin Server prompts for username and password during startup
6) The default maximum capacity for JDBC Datasource is 25
Q10. How to change from development mode to production mode in Weblogic 10.3?
To change Weblogic start-up mode from DEV to production. One way to change it is, by simply editing setDomainEnv.cmd which resides in $root_domain/bin folder.
1. Look for the line that sets the PRODUCTION_MODE script variable: set PRODUCTION_MODE
Add false to the value of the PRODUCTION_MODE variable to ensure the server starts in development
Set true for starting in prod mode.
2. Save your changes and exit the text editor.
Q11. What are the supported installation modes for WebLogic Server?
Graphical mode, console mode and silent mode.
WebLogic installation can happen via 3 different modes:
Console mode: This installation mode is based on the interactive text messages.
Graphical mode: This installation mode is based on the interactive GUI.
Silent mode: This installation mode is based on the properties file that is provided with it, which doesn’t require any interaction as such.
Q12.How to access admin console?
Ssl enabled admin console accessed as :
https://hostname or ip address (where admin server running):(port on which admin server is ssl enabled)
admin console accessed as – Example – https://localhost:7002/console
non ssl admin console accessed as :
http://hostname or ip address (where admin server running):(port on which admin server is ssl enabled )
admin console accessed as – Example – http://localhost:7001/console
Q13. What is the default port of Weblogic admin server?
By default Weblogic, admin server configured on port 7001 and SSL is on 7002.
Q14.How many admin consoles possible in a single domain?
Q15.What is boot.proerties file in weblogic server?
boot.properties is the file used by admin or managed server during startup for username and password. it exists under your domain/servers/server_name/security folder.
Q16.What is config.xml?
config.xml is the central configuration repository for a domain. Every resource you have configured from admin console or by command line or by any other tool registered under this file. WLS 9.x onwards, this file contain references to other xml configuration files also those are under your domain/config folder ( further sub folder under it for respective resources ).
Q17 How do I provide User credentials for starting weblogic server?
When you create a domain, the Configuration Wizard prompts you to provide the username and password for an initial administrative user. If you create the domain in development mode, the
wizard saves the username and encrypted password in a boot identity file. A WebLogic Server instance can refer to a boot identity file during its startup process. If a server instance does not find such a file,it prompts you to enter credentials.
If you create a domain in production mode, or if you want to change user credentials in an existing boot identity file, you can create a new boot identity file.
Q18.Can I start a Managed Server if the Administration server is unavailable?
By default, if a Managed Server is unable to connect to the specified Administration Server during startup, it can retrieve its configuration by reading a configuration file and other files directly. You cannot change the server’s configuration until the Administration Server is available. A Managed Server that starts in this way is running in Managed Server Independence mode.
Q19. What Is a WebLogic Server Cluster?
A WebLogic Server cluster consists of multiple WebLogic Server server instances running simultaneously and working together to provide increased scalability and reliability. A cluster appears to clients to be a single WebLogic Server instance. The server instances that constitute a cluster can run on the same machine, or be located on different machines. You can increase a cluster’s capacity by adding additional server instances to the cluster on an existing machine, or you can add machines to the cluster to host the incremental server instances. Each server instance in a cluster must run the same version of WebLogic Server.
Q20.What is the advantage of clustering?
WebLogic clustering offers three important benefits:
The capacity of an application deployed on a WebLogic Server cluster can be increased dynamically to meet demand. You can add server instances to a cluster without interruption of service — the application continues to run without impact to clients and end-users.
2. Load balancing:
The ability to distribute requests across all members of the cluster, according to the workload on each server.
3. High availability:
A mix of features that ensure applications and services are available even if a server or machine fails. Clients can continue to work with little or no disruption ina highly available environment. WebLogic achieves high availability using a combination of features: replication, failover, and migratable services.
Q21.What is Mulicast and Unicast in weblogic?
Multicast is easier to explain than Unicast. Multicast is a broadcast UDP option for sending a packet/announcement over to a group that is listening on a specific multicast address and port over which the announcement is sent. There is a defined range for valid Multicast address (188.8.131.52 to 184.108.40.206). Everyone listening on the given address hears the announcement just like following a Twitter post. Some limitations with Multicast is the TTL (time to live) across machines/subnets/routers needs to be adjusted and the routers configured to retransmit the multicast packet across subnets
Unicast is more of a point to point UDP option to send the packet to a specific member and not everyone. That way unicast is more of a private conversation between two individuals while multicast is more of a shout to a group or room. Both are UDP based, so there can be losses unlike TCP that handles retransmissions on message loss. But Unicast can span across routers and does not have to worry about TTL without the everyone hearing the announcement. So, Network Admins in general prefer to go with Unicast over Multicast for these reasons
Q23.What is Horizontal and vertical clustering?
There are two method of clustering Horizontal and Vertical.
Horizontal clustering: involves running multiple Java application servers that are run on two or more separate physical machines. Horizontal scaling is more reliable than vertical scaling, since there are multiple machines involved in the cluster environment, as compared to only one machine
Vertical clustering: however, consists of multiple Java application servers on a single physical machine. With vertical scaling, the machine’s processing power, CPU usage, and JVM heap memory configurations are the main factors in deciding how many server instances should be run on one machine.
Q24. How Does a Cluster Relate to a Domain?
A cluster is part of a particular WebLogic Server domain. A domain is an interrelated set of WebLogic Server resources that are managed as a unit. A domain includes one or more WebLogic Server instances, which can be clustered, non-clustered, or a combination of clustered and non-clustered instances. Domain can include multiple clusters. A domain also contains the application components deployed in the domain, and the resources and services required by those application components and the server instances in the domain.
Q25.What is Node Manager?
Node Manager is program that is used to control WebLogic Server instances. A single Node Manager instance is used to control all of the server instances running on the same physical machine or different machine. These instances can reside in different clusters, domains, and such. You must configure each machine in your domain to communicate with Node Manager.
Q.26 How many way to start and stop weblgic servers?
There are many ways to start & stop weblogic Admin and managed servers. You can start and stop Admin Server using :
2) “Java weblogic.server “command(The weblogic.Server class is 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:
2) admin console
3) using WLST
4) using node manager
5) java weblogic.server command( The weblogic.Server class is the main class for a WebLogic Server instance )
Q27.How many types you configure managed server in weblogic server?
1)Domain Configuration Wizard
3)Weblogic Scripting Tool
Q28. How to know weblogic version?
In the WebLogic console, in the left navigation tree, click on “Environment”, then “Servers”.
Then click on one of the servers in the list. Then click on the “Monitoring” tab. Look at the “WebLogic Version” field.
Q29 .How do you set the classpath?
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)
Q30.How does a server know when another server is unavailable?
WebLogic Server uses two mechanisms to determine if a given server instance is unavailable. Each WebLogic Server instance in a cluster uses multicast to broadcast regular “heartbeat” messages that advertise its availability. By monitoring heartbeat messages, server instances in a cluster determine when a server instance has failed. The other server instances will drop a server instance from the cluster, if they do not receive three consecutive heartbeats from that server instance WebLogic Server also monitors socket errors to determine the availability of a server instance. For example, if server instance A has an open socket to server instance B, and the socket unexpectedly closes, server A assumes that server B is offline.
Q31. How do you differentiate between a server hang and server crash issue?
When a Server crashes, the JAVA process no longer exists. When the Server is hung, it stops responding.
We can use the WebLogic .ADMIN utility to ping the server. In case of a hang situation we can take multiple thread dumps and analyze the cause of hang
Q32.How are notifications made when a server is added to a cluster?
The WebLogic Server cluster broadcasts the availability of a new server instance each time a new instance joins the cluster. Cluster-aware stubs also periodically update their list of available server instances.
Q33 How do I turn the auto-deployment feature off?
The auto-deployment feature checks the applications folder every three seconds to determine whether there are any new applications or any changes to existing applications and then dynamically deploys these changes. The auto-deployment feature is enabled for servers that run in development mode.
To disable the auto-deployment feature, use one of the following methods to place servers in production mode:
=>In the Administration Console, click the name of the domain in the left pane, then select the Production
Mode checkbox in the right pane.
=>At the command line, include the following argument when starting the domain’s Administration
Production mode is set for all WebLogic Server instances in a given domain.
Q34. How managed servers communicate with each other ?
Managed servers communicate each other using t3 protocol internally.
Q35. What is SSL in weblogic?
Secure Sockets Layer (SSL) provides secure connections by allowing two applications connecting over a network connection to authenticate the other’s identity and by encrypting the data exchanged between the applications. Authentication allows a server and optionally a client to verify the identity of the application on the other end of a network connection. Encryption makes data transmitted over the network intelligible only to the intended recipient.
Q36. How you deploy your applications on weblogic server?
These are the types.
1) Auto Deployment
3) Command line – weblogic.deployer
4) ANT / WLST
Q37. What are stating modes are available in Weblogic Server ?
There are three starting modes are available:
1) Stage mode: Administration Server copies the deployment files from their original location on the Administration Server machine to the staging directories of each target server
2) External Stage: target servers deploy using local copies of the deployment files, here the Administration Server does not automatically copy the deployment files to targeted servers in external_stage mode ; instead, you must copy the files to the staging directory of each target server before deployment.
3) No Stage: The Administration Server does not copy deployment unit files; instead, all servers deploy using the same physical copy of the deployment files, which must be directly accessible by the Administration Server and target servers
Q38. What is a Thread dump? How will you take in unix/linux and windows?
A Java thread dump is a way of finding out what every thread in the JVM is doing at a particular point in time. This is especially useful if your Java application sometimes seems to hang when running under load, as an analysis of the dump will show where the threads are stuck.
1) Linux : kill -3 <ps_id>
2) Windows (console mode) : crtl+break
3) Windows (service) : beasvc -dump -svcname:mydomain_myserver
Q39. What can be the various reasons for a server crash?
a) Native IO
b) SSL Native Libraries
d) Supported Configuration
e) JDBC Driver issue
Q40. How do you troubleshoot Server Hang?
We can use java weblogic.Admin PING to check if we get a normal response.
We need to take multiple thread dumps with kill -3 pid on unix and CTLR Break on Windows. Analyze the thread dump to find the root cause.
Q41. What can be the reasons of Server hang?
Memory leak, database query taking a long time to return, Deadlock.
Q42. What is a memory leak?
The memory leak is when objects are not removed from the heap even when they are not required
Q43. What are the various causes for OUT OF MEMORY?
a) Insufficient heap size, not able to match the extra load.
b) Objects licing too long, like HTTP Sessions.
c) Memory leak in application code.
d) Full GC not happening due to JVM Bug.
Q44. What is HTTP tunneling? How can we configure it on Weblogic?
HTTP tunneling provides a way to simulate a stateful 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
Q45. What is the difference between T3 and HTTP protocol?
WebLogic uses the T3 protocols for internal and external connections to the servers. The T3 protocol often is used in WebLogic’s implementation of RMI. Proprietary of WebLogic Server.
Http protocols are used primarily for HTTP communication between the browser and the web server.
Q46. Can you tell difference between JMS topic and JMS queue?
JMS Queues delivers messages to one consumer, JMS topic to multiple consumers.
Q47. Weblogic is currently owned by which company and originally by which? or What is the full form of BEA?
Originally Weblogic was owned by BEASystem. Later purchased by Oracle Inc. Three guys named Bill, Ed Scott, and Alfred founded it in 1995. So they took the first letter of their name.
Q48. What is work managers in weblogic? It’s types.
Weblogic server allows you to configure, how your application prioritizes the execution of its work. Based on rules and constraints you can define how WebLogic Server prioritizes work and allocates threads based on an execution model that takes into account administrator-defined parameters and actual run-time performance and throughput. Work manager applying it either globally or to a specific application component.
1.Default work managers: WLS implements a default work manager when no-other work managers are specified.
2.Global work manager: Global work managers are created in Weblogic administrative console and are defined in config.xml it is created as a template.
3.Application scoped work managers: Work managers available only to a specific application (or) module.
Appplication Work Managers can be configured at the
3.3. module level
in one of the following configuration files:
config.xml—Work Managers specified in config.xml can be assigned to any application, or application component, in the domain. You can use the Administration Console to define a Work Manager.
Weblogic-application.xml—Work Managers specified at the application level can be assigned to that application or any component of that application.
weblogic-ejb-jar.xml or weblogic.xml—Work Managers specified at the component-level can be assigned to that component.
weblogic.xml—Work Managers specified for a Web Application.
Q49.Explain deployment descriptors?
Deployment descriptors are associated with almost all the modules as well as applications. The deployment descriptors can be seen in the form of XML documents and they are capable of describing the contents that are part of directory or the jar file. J2EE specifications usually define the standard as well as the deployment descriptors which are portable for J2EE applications and modules.
A WebLogic Server has its own web deployment descriptor, which is defined in the weblogic.xml file.
Q50.What is web.xml ?
Web.xml is an XML document that is mainly for application purpose and it helps in listing out the J2EE components and configuration that of your application in J2EE modules format
Q51.What is JNDI?
(Java Naming and Directory Interface)
Applications use naming services to locate objects data sources, EJBs, JMS, MailSessions, and so on within the WebLogic domain. A naming service associates names with objects and finds objects t3 protocol will be used. (The RMI registry is a good example of a naming service.)
JNDI provides a common-denominator interface to many existing naming services, such as LDAP (Lightweight Directory Access Protocol) and DNS (Domain Name System). These naming services maintain a set of bindings, which relate names to objects and provide the ability to look up objects by name. JNDI allows the components in distributed applications to locate each other.
The WebLogic Server implementation of JNDI supplies methods that:
Give clients access to the WebLogic Server naming services
Make objects available in the WebLogic namespace
Retrieve objects from the WebLogic namespace
Q52.What is a domain template?
A domain template is a jar file default one is wls.jar file, which is ‘/bea/weblogic81/common/templates/domains/, it has all the features that is required for the standard weblogic domain, we can even create domain template of our own configuration. by this template we dont have to configure every time we create a new domain.
By using template we can: Create servers, Clusters, Machines, Configure services such as JMS, JDBC, Applications.
Q53. What is nmenroll in WLST?
The nmEnroll() method is used for enrolling the machine with the WebLogic domains running on that. It is the name and its path.
the Nodemanager always gets the domain information from the Administration server provided that it should have enrolled in that machine.
Q54. How do you provide load balancing?
In the WebLogic Cluster side we have 3 basic types and each supports Affinity based also.
I) Round Robin
iii) Weight based
Q55. How to test the port is existing or not in unix? or how to know if the required port is listening or not.
netstat -nap | grep <port_no>
Q56. How to test the port is existing or not in unix?
The WebLogic whole configuration stored into a repository file config.xml in config folder present in the domain directory.
Location is $Domain_home/config/config.xml
Q57. How many Administration servers and managed servers should be there in weblogic?
In a WebLogic domain there must be a single Admin server and there can be as many as managed servers as per the need and capacity limitations of the environment.
Q58. What Is A Stage Deployment?
Stage deployment is a kind of process in which the admin gets a physical copy which is distributed to the other instances(managed server)
Q59. What Is Non-stage Deployment?
There is no copy in the administrator but each and every server needs to contact the source directly for getting the item to be deployed
Q60. What Is The Name Of Default Jvm That Is Made Used For Weblogic?
The sun hotspot JDK default is made used for development, JRockit is the one used for production of WebLogic 11g as well as 12c.
Q61.Explain about the function associated with T3 in WebLogic server ?
T3 provides enhancements support for the messages of WebLogic server. The enhancements comprise of the object replacement, the working of the seblogic server – clusters and also HTTP. T3 also performs serialization of java object and also predation of RMI. T3 can be considered as a superset associated with java object. T3 is mandated between WebLogic servers, programmatic clients and cluster associated with WebLogic server. The protocols HTTP and IIOP are made used for enabling communication between WebLogic server and processes.
Q62. How can classpath be set?
Classpath can be set by making use of the following script WL_HOME\server\bin\setWLSEnv.sh
Q63. What is Graphic mode in weblogic ?
It is a kind of installation type that makes use of interactive GUI.
Q64. What is console mode?
This is a kind of installation type that follows interactive text based method.
Q65. What is silent mode?
This is a method of installation that is non-interactive and is usually based on the .xml properties – file.
Q66. What is Unicast?
Unicast is the method used in the clustering technique where there are cluster master and each server should ping to this cluster master for informing that the server is alive.
Q67. What is Multicast?
It is a kind of clustering system where there is no cluster master and each and every server needs to ping each other for informing their existence. Multicasting has many messages to be sent in the form of ping as each server needs to inform all others about its existence. This condition creates much complexity associated with the method compared to unicast.
Q68. How to check the version of Java?
Q69. How to check which java is being used.
Q70. What is the BSU in weblogic ? what is use of it ?
BSU Stands for Bea Smart Update. This utility is used to apply the WebLogic Server Patches.
Q71. What are the States of the Weblogic Server?
There are 9 states of server which are given below
- Shutting down
Q72. What you Can Do with Node Manager ?
We can manage many 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
Q73. How to check port number?
netstat -na |grep connected (to find the ports connected in Linux box.)
netstat -na |grep listen (to find the listening ports in HP-UX,Solaris)
Q74. What are Locks in weblogic
There are 4 types of loc k available in weblogic
config.lok: This is used for getting the file lock on the config.xml file. This lock ensures that the config.xml file is being owned by only one process at a time. This also ensures that the updates to the config.xml file are done in sequential order.
Location : $Domain_Home/config/config.xml
edit.lok: This was the most important lock that we see. This lock ensures that only one user is editing the configurations at any point in time. No 2 operations are performed at the same time
Location : $Domain_Home/
embeddedLDAP.lok: This file locks access to the embedded ldap server to ensure that only one person has access to the directory server at any time. Location $Domain_Home/servers//data/ldap/ldapfiles/
XXXServer.lok:This lock indicates that a given server is running.This ensures that the server is not started or running multiple times.
Location : $Domain_Home/servers/servername.lok
When a webloigc server is stopped, the embeddedLDAP.lok and XXXservername.lok are deleted automatically.
Q75.What is Garbage collection?
Garbage collection (GC) is a form of automatic memory management. The garbage collector attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program.
Q76. What is the difference between the stage and the non-stage deployments?
Stage deployment can be understood as the process where the Admin gets a copy which is later on distributed amongst the available instances. Whereas the Non-Stage deployment has a restriction that each instance needs to contact the source for the necessary deployments.
Q77. In how many ways can we provide credentials to start the WebLogic server?
Command-line: During the creation of a domain, details like the username and password are prompted for via a wizard to configure.
Via boot.properties file: If a domain is already created in Development mode, then the encrypted credentials are stored in an identity file. Password can then be entered if this identity file isn’t available during the boot-up process.
Java Option: On a new boot, we can create a new identity file with the credentials or if there’s a requirement to create a new domain in Production mode.
Q78. What are the various ways in which we can start/stop a WebLogic server?
There are many ways by which the WebLogic server services can be started or stopped. They are listed as follows:
Using command java weblogic.server
From Windows services
WLST with or without Node Managers
Q79. What are the various ways in which we can start/stop a WebLogic server?
There are many ways by which the WebLogic server services can be started or stopped. They are listed as follows:
Using command java weblogic.server
From Windows services
WLST with or without Node Managers
Q80. How do you set a CLASSPATH in a WebLogic server?
You can use the script files from WebLogic to set CLASSPATH for the requirements. These are the files that we have to use based on the OS type (Windows or Linux):
1. WL_HOME/server/bin/setWLSEnv.cmd for Windows
2. WL_HOME/server/bin/setWLSEnv.sh for Linux
Q81. What is your understanding on BSU in WebLogic server?
WebLogic Smart Update or BEA Smart Update utility (BSU) is a utility available to update or apply patches on WebLogic Servers. It can be found under the following folder (WL_HOME/utils/bsu).
Q82. What is your understanding of the functionality of IIOP?
IIOP is a protocol that helps with the communication between WebLogic servers and Object Request Brokers.
Q83. What is the name of the default JVM which is used for a WebLogic server?
The Sun HotSpot JDK is the default JVM that is available for development whereas JRockIt is the JVM that is used for the production of WebLogic servers. Based on the OS that is being used, the choice of Certified JDK / JVM depends.
Q84. How do we change the default JVM to another one?
The process to change the default JVM to another one is as follows:
- Update the JAVA_HOME variable in the start script of the server
- Modify your config.xml of the domain to point it to JRockit javac.exe
- Check and modify accordingly to clip off any references to Sun JVM from the startup scripts.
Q85. How do we create pooling within Tomcat server?
To create pooling in Tomcat server, follow the steps mentioned below:
1.Download and add these jars to Tomcatlib folder – commons-dbcp-1.2jar, commons-pool-1.3.jar, commons-collections-3.1.jar.
2.Provide an entry in the server.xml under Tomcatconfig folder.
Q86. Why is the Node Manager required?
Node Manager is a Java-based utility that comes in handy to perform some common operations for a given Managed server. It runs as a totally different service than from the WebLogic server.
Q87. How does stubs work in a WebLogic Server cluster?
Stubs perform the removal of nodes from the WebLogic server cluster, whenever it identifies one. DNS comes into picture for the stubs to identify working server nodes and the list of available nodes gets updated periodically to keep the whole cluster available.
Q88. How do you analyze a server crash?
A server crash always comes with a corresponding hs_err_pid file which contains the actual cause of the crash in the first place. You can refer to this file and identify the cause of the issue and basis on that, we can take the next steps:
1.If it is a driver related issue, reach out to the respective driver teams
2.If it is related to the Native IO issue, kindly disable and find an appropriate cause.
Q89. How do you go about analyzing a server hang issue?
A server hang issue is relatively different from a server crash, where there could be possibly different sets of reasons for it to happen – lack of resources, unimaginable load, other parameters that affect the system, etc.
Firstly we can use the following command to see if you get a good response:
1.java weblogic.admin ping
2.Based on the outcome of this command, you can probably check for the cause of the issue.
Q90. What are the possible causes of OUT OF MEMORY?
There can possibly the following possibilities for an OUT OF MEMORY issue:
Heap size would’ve less compared to the load received
Resource leaks from the application code itself.
Any JVM bugs that alter the occurrence of a full GC
Placing of objects taking longer than that of a given HTTP session
Q91. Differentiate between Sun JVM and the BEA JRockit JVM.
Sun’s implementation of the JVM is called the HotSpot and is also shipped in the JDK, JRE from Sun / Oracle. BEA JRockit JVM is a custom implementation from BEA for reliability, performance for the server-side applications. For this to be achieved, BEA JRockit JVM uses hot spot detection, code generation, advanced garbage collection, tight OS integration.
Q92. How can one tune the performance of a WebLogic server?
The performance of a WebLogic server can be done at 4 different levels, which are as follows:
Tuning GC strategy
Core server Tuning:
Tune Chunk pool and Chunk size
By using performance packs
Tune Work manager
Connection backlog buffering
Setting the TCP IP parameters such as tcp_conn_req_max_q and tcp_time_wait_interval.
Pre-compile of JSPs
EJB pool size cache
Q93. What is Core Server tuning?
This is the process of tuning your WebLogic core server with the following parameters to consider – chunk pool, chunk size, tune work manager, connection backlog buffering etc.
Q94. What is your understanding on WebLogic Cache Server?
A WebLogic cache server (also known as a Reverse Proxy) helps speed up the Web traffic. The basic understanding is that the Web traffic can be graphic intensive and there is a definite need for caching the repetitive pages. If not done, then it might slow down the Web traffic.
Q95. Why do we need to clear the WebLogic Cache? How do you achieve it?
The need to clear the WebLogic Cache comes in when you go for a newer version deployment. That is when we need to clear the WebLogic Cache. We can achieve this by the following means:
Removing these Cache folders manually after the WebLogic server is brought down gracefully.
Use the stage mode to no_stage deployment, by doing this the Cache gets cleared automatically whenever an application is undeployed.
Q96. What is your understanding of the various error codes within the WebLogic server?
The error codes within WebLogic Server range from BEA-000001 to BEA-2163006. The types of errors that these mentions are classified as below:
Q97. When we will take Thread dump? Please give us some examples
Some of the examples would be
1. when the server is in 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. The server cannot accept further requests because sockets cannot be created
5. Infinite Looping in the code
Q98. How to check port number?
netstat -na |grep connected (to find the ports connected in Linux box.)
netstat -na |grep listen (to find the listening ports in HP-UX,Solaris)
Q99. Explain the different modes of the WebLogic server?
There are two different modes in the WebLogic server – namely Development mode and Production mode. Differences between these modes are as follows:
|Development Mode||Production Mode|
|Default JDK is Sun HotSpot||Default JDK is BEA JRockit|
|Usage of demo certificates for SSL is allowed||Usage of demo certificates for SSL will throw warnings.|
|Auto-deployment to ADMIN server (only) is enabled by default||Auto-deployment to ADMIN server (only) is disabled by default|
|On startup, server instances rotate their log files||Server log files rotate when they reach a limit of 5MB|
|ADMIN server uses an automatically created boot.properties file for the login credentials.||ADMIN server prompts for credentials during startup|
|Default of maximum JDBC datasources is 15||Default of maximum JDBC data sources is 25|
|ClassLoader analysis tool, Web Service test client are available||ClassLoader analysis tool, Web Service test client are not available|
|Node Manager login credentials are the same as Admin Server credentials||Node Manager login credentials are randomly generated|
Q100. What are the capabilities of Weblogic Server?
There are various capabilities associated with WebLogic server and they are
- Changes in dynamic configuration
- Production application redeployment
- Rolling upgrades
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