interview

what are the web servers and app servers?

Web servers are computers that deliver (serves up) Web pages. Every Web server has an IP address and possibly a domain name.
--->For example, if you enter the URL http://www.webopedia.com/index.html in your browser,
this sends a request to the Web server whose domain name is webopedia.com.

What is an example of a Web server?

The process is an example of the client/server model. All computers that host Web sites must have Web server programs.
Leading Web servers include Apache (the most widely-installed Web server),
Microsoft's Internet Information Server (IIS) and nginx (pronounced engine X) from NGNIX.

why web servers are used ?

A web server communicates with a web browser using the Hypertext Transfer Protocol (HTTP). ...
While web servers typically host websites that are accessible on the Internet,
they can also be used to communicate between web clients and servers in local area networks such as a company's intranet.

is tomcat web server ?

Tomcat is a web server and a Servlet/JavaServer Pages container.
It is often used as an application server for strictly web-based applications
but does not include the entire suite of capabilities that a Java EE application server would supply. ...
Apache Tomcat home page

What does a web server do?

The primary function of a web server is to store, process and deliver web pages to clients.
The communication between client and server takes place using the Hypertext Transfer Protocol (HTTP).

How do I download a Web server?

you can install Apache anywhere, such as a portable USB drive (useful for client demonstrations).
Step 1: configure IIS, Skype and other software (optional) ...
Step 2: download the files. ...
Step 2: extract the files. ...
Step 3: configure Apache. ...
Step 4: change the web page root (optional) ...
Step 5: test your installation.

What is the difference between Apache and Tomcat?

Apache Tomcat is used to deploy your Java Servlets and JSPs.
So in your Java project you can build your WAR (short for Web ARchive) file,
and just drop it in the deploy directory in Tomcat.
So basically Apache is an HTTP Server, serving HTTP.
Tomcat is a Servlet and JSP Server serving Java technologies.
is jboss web server or application server.
For example, Apache httpd is a web server and Tomcat is an application server. ...
For web server you use JSP, Servlet. Application Server --
it works on any protocol. example is JBOSS.

What is server?

A server is a computer program that provides a service to another computer programs (and its user). ...
In the client/server programming model, a server program awaits and fulfills requests from client programs,
which may be running in the same or other computers.
Syntax for a Server Network Address.
Typically, the server address is a system name (if the systems are in the same domain),
A fully qualified domain name, or an IP address:
If the systems are the same domain, you can use the name of the computer system; for example, SYSTEM46.

Is server a computer program ?

In computing, a server is a computer program or a device that provides functionality for other programs or devices, called "clients".
This architecture is called the client–server model,
and a single overall computation is distributed across multiple processes or devices.

What are the features of Web server?

Features of Web Server
Virtual hosting.
Support for large files.
Bandwidth throttling to regulate network traffic and mitigate bandwidth congestion.
Server-side scripting for the creation of dynamic web pages.
Hardware comes with built-in reliability and is designed to suit business critical needs and budget constraints.

What is Apache Tomcat Server tutorial?

Tomcat version 7.x is used in this tutorial.
Apache Tomcat. Apache Tomcat is a web container which allows to run servlet and JavaServer Pages (JSP) based web applications.
Installation. 2.1. ...
Managing Apache Tomcat. ...
Developing Java web applications. ...
Tomcat as HTTP Server. ...
Links and Literature. ...
Appendix A: Copyright and License.

What is difference between Jboss and Tomcat?

The Major Differences Between JBoss and Tomcat. Both JBoss and Tomcat are Java servlet application servers, but JBoss is a whole lot more. ...
One way to think of it is that JBoss is a JEE stack that includes a servlet container and web server, whereas Tomcat,
for the most part, is a servlet container and web server.
The process is an example of the client/server model.
All computers that host Web sites must have Web server programs.
Leading Web servers include Apache (the most widely-installed Web server),
Microsoft's Internet Information Server (IIS) and nginx (pronounced engine X) from NGNIX.
A server room is a room used to store, power and operate computer servers and their associated components.
This room is part of a data center, which typical houses several physical servers lined up together in different form factors,
such as rack mounted, or in tower or blade enclosures.

How do I find my server address?

To find your Host Name and Physical Address using the Windows Command Prompt:
Open the Command Prompt window by clicking on Start > (All) Programs > Accessories > Command Prompt. ...
Type ipconfig /all and press the Enter key.

How do I make my PC into a server?

Make Your Computer Into a Server in 10 Minutes (free Software)
Step 1: Download Apache Server Software. Download the apache http server software from this apache mirror site: ...
Step 2: Install It. ...
Step 3: Run It. ...
Step 4: Test It.

What are the types of servers?

Server Types

Proxy Server. ...
Mail Server. ...
Server Platforms. ...
Web Server. ..
Application Server. ...
Real-Time Communication Server.
FTP Server. ...
Collaboration Server

Is Apache a Web server?

The Apache HTTP Server, colloquially called Apache (/?'pæt?i?/ ?-PATCH-ee), is a free and open-source cross-platform web server,
released under the terms of Apache License 2.0.
Apache is developed and maintained by an open community of developers under the auspices of the Apache Software Foundation.

The Apache HTTP server is a software (or program) that runs in the background under an appropriate operating system,
which supports multi-tasking, and provides services to other applications that connect to it, such as client web browsers.

What is the difference between Apache and Tomcat?

Apache Tomcat is used to deploy your Java Servlets and JSPs.
So in your Java project you can build your WAR (short for Web ARchive) file, and just drop it in the deploy directory in Tomcat.
So basically Apache is an HTTP Server, serving HTTP.
Tomcat is a Servlet and JSP Server serving Java technologies
Tomcat is a web server and a Servlet/JavaServer Pages container.
It is often used as an application server for strictly web-based applications
but does not include the entire suite of capabilities that a Java EE application server would supply. ...
Apache Tomcat home page.

Q.What are safeguards for modifying the config.xml file?

A. BEA recommends that you use the WebLogic Server Administration Console to edit the config.xml file. If you need to edit the config.xml file directly, we recommend that:
You always save a copy of your config.xml file before editing it. If your edits
cause errors that prevent you from booting, you can at least revert to your saved
version.
You manually edit the config.xml file for a domain when a domain is not
active. If you edit the configuration file while the domain is active, any changes
you make manually will likely be overwritten by the system. Furthermore, all
changes you make by hand while the domain is active are ignored by the system
at run time.
Because there is no validation or value checking when you edit config.xml
manually, type-checking occurs when you load the configuration file for the first
time, that is, when you restart the Administration Server. At that point, any
invalid XML or attribute value is detected and the domain fails to boot.
For more information on modifying the config.xml file, see information on the
config.xml.booted file in the Starting and Stopping WebLogic Servers section of
the Administration Guide

How do I edit the config.xml file?

A. The persistent configuration for a domain of WebLogic Servers and clusters is
stored in an XML configuration file (config.xml). You can modify this file in the
following ways:
The recommended way for users to modify or monitor a domain's configuration
is to use the Administration Console.
WebLogic Server includes a configuration Application Programming Interface
(API), which programs can use to modify configuration attributes of resources in
the domain.
You can access the attributes of a domain with the WebLogic Server
command-line utility. This utility is provided for people who want to create
scripts to automate domain management. See Commands for Managing a
WebLogic Domain in the Administration Guide at
http://e-docs.bea.com/wls/docs61/adminguide/cli.html.

Q. How do stubs work in a WebLogic Server cluster?
A. Clients that connect to a WebLogic Server cluster and look up a clustered object
obtain a replica-aware stub for the object. This stub contains the list of available server
instances that host implementations of the object. The stub also contains the load
balancing logic for distributing the load among its host servers.

Q. What happens when a failure occurs and the stub cannot connect to a WebLogic
Server instance?
A. When the failure occurs, the stub removes the failed server instance from its list.
If there are no servers left in its list, the stub uses DNS again to find a running server
and obtain a current list of running instances. Also, the stub periodically refreshes its
list of available server instances in the cluster; this allows the stub to take advantage of
new servers as they are added to the cluster.

Q. How does a server know when another server is unavailable?
A. 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.

Q. How are notifications made when a server is added to a cluster?
A. 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.

Q. How do clients learn about new WebLogic Server instances?
A. Once a client has done a JNDI lookup and begins using an object reference, it finds
out about new server instances only after the cluster-aware stub has updated its list of
available servers.

Q. How do clients handle DNS requests to failed servers?
A. If a server fails and DNS continues to send requests to the unavailable machine,
this can waste bandwidth. For a Java client application, this problem occurs only
during startup. WebLogic Server caches the DNS entries and removes the unavailable
ones, to prevent the client from accessing a failed server twice.
Failed servers can be more of a problem for browser-based clients, because they
always use DNS. To avoid unnecessary DNS requests with browser-based clients, use
a third-party load-balancer such as Resonate, BigIP, Alteon, and LocalDirector. These
products mask multiple DNS addresses as a single address. They also provide more
sophisticated load-balancing options than round-robin, and they keep track of failed
servers to avoid routing unnecessary requests.

Q. Why did my JDBC code throw a rollback SQLException?
A. Your JDBC code may throw the following exception:
"The coordinator has rolled back the transaction.
No further JDBC access is allowed within this transaction."
The WebLogic JTS JDBC driver throws this exception when the current JDBC
connection transaction rolls back prior to or during the JDBC call. This exception
indicates that the transaction in which the JDBC connection was participating was
rolled back at some point prior to or during the JDBC call.
The rollback may have happened in an earlier EJB invoke that was part of the
transaction, or the rollback may have occurred because the transaction timed out. In
either case, the transaction will be rolled back, the connection returned to the pool and
the database resources released. In order to proceed, the JTS JDBC connection must
be closed and reopened in a new transaction.

Q. Must EJBs be homogeneously deployed across a cluster? Why?
A. Yes. Beginning with WebLogic Server version 6.0, EJBs must be homogeneously
deployed across a cluster for the following reasons:
To keep clustering EJBs simple
To avoid cross server calls which results in more efficiency. If EJBs are not
deployed on all servers, cross server calls are much more likely.
To ensure that every EJB is available locally
To ensure that all classes are loaded in an undeployable way
Every server must have access to each EJB's classes so that it can be bound into
the local JNDI tree. If only a subset of the servers deploys the bean, the other
servers will have to load the bean's classes in their respective system classpaths
which makes it impossible to undeploy the beans.

1)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.
--
within the cluster all the server instances are sending heart beat messages, if any sever not respond for three consecutive heart beats that particular server point or mark as a server failed or server unavailable

2)How do stubs work in a WebLogic Server cluster?

Clients that connect to a WebLogic Server cluster and look up a clustered object obtain a replica-aware stub for the object. This stub contains the list of available server instances that host implementations of the object. The stub also contains the load balancing logic for distributing the load among its host servers.

What happens when a failure occurs and the stub cannot connect to a WebLogic Server instance?

When the failure occurs, the stub removes the failed server instance from its list. If there are no servers left in its list, the stubb uses DNS again to find a running server and obtain a current list of running instances. Also, the stub periodically refreshes its list of available server instances in the cluster; this allows the stub to take advantage of new servers as they are added to the cluster.

3) What is the function of T3 in WebLogic Server?
T3 provides a framework for WebLogic Server messages that support for enhancements. These enhancements include abbreviations and features, such as object replacement, that work in the context of WebLogic Server clusters and HTTP and other product tunneling. T3 predates Java Object Serialization and RMI, while closely tracking and leveraging these specifications. T3 is a superset of Java Object. Serialization or RMI; anything you can do in Java Object Serialization and RMI can be done over T3. T3 is mandated between WebLogic Servers and between programmatic clients and a WebLogic Server cluster. HTTP and IIOP are optional protocols that can be used to communicate between other processes and WebLogic Server. It depends on what you want to do. For example, when you want to communicate between a browser and WebLogic Server-use HTTP, or an ORB and WebLogic Server-IIOP.

4) Setting Up WebLogic Server for HTTP Tunneling
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. However, you can expect some performance loss in comparison to anormal socket connection.

Configuring the HTTP Tunneling Connection Under the HTTP protocol, a client may only make a request, and then accept a reply from a server. The server may not voluntarily communicate with the client, and the protocol is stateless, meaning that a continuous two-way connection is not possible.

WebLogic HTTP tunneling simulates a T3Connection via the HTTP protocol, overcoming these limitations. There are two attributes that you can configure in the Administration Console to tune a tunneled connection for performance. It is advised that you leave them at their default settings unless you experience connection problems. These properties are used by the server to determine whether the client connection is still valid, or whether the client is still alive.

Enable Tunneling

Enables or disables HTTP tunneling. HTTP tunneling is disabled by default.

Note that the server must also support both the HTTP and T3 protocols in order to use HTTP tunneling.

Tunneling Client Ping

When an HTTP tunnel connection is set up, the client automatically sends a request to the server, so that the server may volunteer a response to the client. The client may also include instructions in a request, but this behavior happens regardless of whether the client application needs to communicate with the server. If the server does not respond (as part of the application code) to the client request within the number of seconds set in this attribute, it does so anyway. The client accepts the response and automatically sends another request immediately.

Default is 45 seconds; valid range is 20 to 900 seconds.

Tunneling Client Timeout

If the number of seconds set in this attribute have elapsed since the client last sent a request to the server (in response to a reply), then the server regards the client as dead, and terminates the HTTP tunnel connection. The server checks the elapsed time at the interval specified by this
attribute, when it would otherwise respond to the client's request.

Default is 40 seconds; valid range is 10 to 900 seconds.

5) How can I set deployment order for applications?
WebLogic Server allows you to select the load order for applications. WebLogic Server deploys server-level resources (first JDBC and then JMS) before deploying applications. Applications are deployed in this order: connectors, then EJBs, then Web Applications. If the application is an EAR, the individual components are loaded in the order in which they are declared in the application.xml deployment descriptor.

deployment order is
1 Resources (JDBS and JMS)
2 jsp's and servlets
3 EJB, RMI
4 start up and shutdown classes (optional)

6) How to increase the memory in Weblogic.?
Increase the allocation of Java heap memory for WebLogic Server. (Set the minimum and the maximum to the same size.) Start WebLogic Server with the -ms32m option to increase the allocation, as in this example:
$ java ... -ms32m -mx32m ...
This allocates 32 megabytes of Java heap memory to WebLogic Server, which improves performance and allows WebLogic Server to handle more simultaneous connections. You can increase this value if necessary.
This can be modified in setDomainEnv.sh file, or server start tab in admin console.

Weblogic

What Is Weblogic?

Answer :
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.

Question 2. What Is The Basic Components Of Weblogic Server?

Answer :

These are the basic weblogic components
1)Domains
2)Admin Server
3) Managed Server
4) Node Manager
5) Weblogic Server Cluster

Question 3. What Is The Domain In Weblogic Server?

Answer :

1) Domain is a logically related group of Oracle WebLogic Server resources that are managed as a single unit
2) Domain Provides one point of administration
3) Can logically separate:
A) Development, test, and production applications
B) Organizational divisions

Question 4. What Is The Server?

Answer :

A server is an instance of weblogic.Server executing in a Java Virtual Machine (JVM).
A server:
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

Question 5. What Is The Admin Server?

Answer :

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.

Question 6. What Is The Managed Server?

Answer :

Managed server is a server in a domain that is not the Administration server. It contacts the administration server for configuration information. It runs 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.

Question 7. How Administration Server And Managed Servers Will Interact?

Answer :

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.

Question 8. What Is The Msi Mode In Weblogic? How Can You Enable And Disable This Option?

Answer :

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

Question 9. Difference Between Weblogic Development And Production Mode?

Answer :

Here are some difference between Weblogic Development Mode and Production Mode:
Development 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
Production Mode:
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

Question 10. How To Change From Development Mode To Production Mode In Weblogic 10.3?

Answer :

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.
set PRODUCTION_MODE=false
2. Save your changes and exit the text editor.

Question 11. What Are The Supported Installation Modes For Weblogic Server?

Answer :

Graphical mode
console mode
silent mode
Question 12. What Is The Default Port Of Weblogic Admin Server?

Answer :

By default weblogic admin server configured on port 7001 and SSL is on 7002.

Question 13. What Is Boot.proerties File In Weblogic Server?

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.

Question 14. What Is Config.xml?

Answer :

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 ).

Question 15. How Do I Provide User Credentials For Starting Weblogic Server?

Answer :

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.

Question 16. Can We Start A Managed Server If The Administration Server Is Unavailable?

Answer :

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.

Question 17. What Is A Weblogic Server Cluster?

Answer :

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.
Question 18. What Is The Advantage Of Clustering?

Answer :

WebLogic clustering offers three important benefits:
1. Scalability : 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 tothe workload on each server.
3. High availability : A mix of features that ensure applications and services are available even if aserver or machine fails.Clients can continue to work with little or no disruption ina highly available environment. WebLogic achieves high availability using acombination of features: replication, failover, and migratable services.

Question 19. What Is Multicast And Unicast In Weblogic?

Answer :

Mulicast : Multicast is easier to explain over 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 (224.0.0.1 to 239.255.255.255). 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 : 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

Question 20. What Is Horizontal And Vertical Clustering?

Answer :

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.

Question 21. How Does A Cluster Relate To A Domain?

Answer :

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. A 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.

Question 22. What Is Node Manager?

Answer :

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.

Question 23. How Many Way To Start And Stop Weblogic Servers?

Answer :

There are many ways to start & stop weblogic Admin and managed servers:
You can start and stop Admin Server using :
1) Script
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 :
1) scripts
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 )

Question 24. How Many Types You Configure Managed Server In Weblogic Server?

Answer :

Three types
1)Domain Configuration Wizard
2)Administration Console
3)Weblogic Scripting Tool

Question 25. How To Know Weblogic Version?

Answer :

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.

Question 26. How Do You Set The Classpath?

Answer :

WebLogic Server installs the following script that you can use to set the classpath that a server requires:
WL_HOMEserverbinsetWLSEnv.cmd (on Windows)
WL_HOME/server/bin/setWLSEnv.sh (on UNIX)

Question 27. How Does A Server Know When Another Server Is Unavailable?

Answer :

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

Question 28. How Do You Differentiate Between A Server Hang And Server Crash Issue?

Answer :

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

Question 29. How Are Notifications Made When A Server Is Added To A Cluster?

Answer :

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.

Question 30. How Do I Turn The Auto-deployment Feature Off?

Answer :

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 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 Server:
-Dweblogic.ProductionModeEnabled=true
Production mode is set for all WebLogic Server instances in a given domain.

Question 31. How Managed Servers Communicate With Each Other?

Answer :

Managed servers communicate each other using t3 protocol internally.

Question 32. What Is Ssl In Weblogic?

Answer :

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

Question 33. How You Deploy Your Applications On Weblogic Server?

Answer :

These are the types.
1) Auto Deployment
2) Console
3) Command line – weblogic.deployer
4) ANT / WLST

Question 34. What Are Stating Modes Are Available In Weblogic Server ?

Answer :

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

Question 35. What Is A Thread Dump? How Will You Take In Unix/linux And Windows?

Answer :

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

Question 36. Explain Deployment Descriptors?

Answer :

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.

Question 37. What Is The Name Of Default Jvm That Is Made Used For Weblogic?

Answer :

The sun hotspot JDK default is made used for development, JRockit is the one used for production of WebLogic 11g as well as 12c. Operating system is another factor that helps in choosing the certified JDK JVM.

Question 38. Explain The Methods For Providing User Credentials For Starting The Server?

Answer :

At the time of the creation of domain, the wizard for setting configuration asks for the details like user name, password etc. from the user who is logging in for the first time as an administrator. If the domain is created in development mode, the configuration wizard saves the encrypted password as well as the username inside an identity file. This file is available for reference during the time of booting so that in the absence of this file, system can prompt the user for the purpose of entering credentials. A new boot – identity file can be created if you want to change the use credentials or else if you are having the requirement of creating domain in the production mode.

Question 39. Is There Any Possibility For Starting Managed Server During The Absence Of Administrator Server?

Answer :

The usual process is that in case of any difficulty for the manager server to get connected to any administration server at the time of start up, there is an option for the managed server to retrieve the configuration related to it from the configuration files as well as other files involved. The information thus retrieved cannot be altered and it is possible only when the administration server is really available. When the administration server is unavailable, then the managed server enters into its independence mode for carrying out its operations.

Question 40. What Are The Capabilities Of Weblogic Server?

Answer :

There are various capabilities associated with WebLogic server and they are

Changes in dynamic configuration
Production application redeployment
Rolling upgrades
Question 41. What Is Core Server Tuning?

Answer :

This is the process involving the tuning of work manager, chuck size, performance packs, chunk pool size and connection backlog buffering.

Question 42. How Many Weblogic Servers Can Be Held Inside A Multi-processor Machine?

Answer :

There is no limitation for the number of servers.

Question 43. What Is A Stage Deployment?

Answer :

Stage deployment is a kind of process in which the admin gets a physical copy which is distributed to the other instances.

Question 44. What Is Non-stage Deployment?

Answer :

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.

Question 45. How Can Port Number Be Checked?

Answer :

Port number can be checked by using netstat-na|grep connected.

Question 46. What Are The Various Types Of Weblogic Installations?

Answer :

The WebLogic installation usually occurs in three different modes which are:

Graphical mode
Console mode
Silent mode.
Question 47. Explain The Term Clustering?

Answer :

Clustering is the process of grouping the servers together for accomplishing high percentage of scalability and availability.

Question 48. What Is The Purpose Of Clustering?

Answer :

The major goal of performing the process of clustering is to make high scalability as well as availability of the servers possible. This process also helps in balancing the load in a proper manner and also accomplishes failover.

Question 49. How Can Cluster Communication Occur?

Answer :

The communication through cluster is made possible by the multicast IP as well as port by the process of sending periodic messages which are normally called as heartbeat messages.

Question 50. How Do Stubs Function Inside Weblogic Server Cluster At The Time Of Failure?

Answer :

Stubs perform the process of removing the failed instance from the list whenever there is a failure. The stub usually makes use of DNS for finding the running server and also for obtaining the list of the instances that are currently available with the application. List of the instances available with the server inside cluster gets periodically refreshment and allows in acquiring advantages associated with new servers. The advantages are gained as the server gets added to the cluster.

WebLogic interview

Q) APPLICATION SERVER Vs WEB SERVER
(1) It has got app container (and obviously web container) inside it and thus EJB can be deployed in it 'Vs' (1)It has got web container inside it and it acts as front end where JSPs are deployed on it.
(2) Main business logic is deployed on the app server 'Vs' (2) It is used as proxy in front of app server for load balancing.
(3) Examples of commonly used app servers in market are Weblogic, Websphere, JBoss 'Vs' (3) Examples of commonly used web servers are apache, IIS, Iplanet.

Q) FEATURE OR ADVANTAGES OF APP SERVER?
1.Clustering
2.Loadbalancing
3.High availibility
4.Failover

Q) SESSION REPLICATION:
It is the mechanism by which session & session related data is transferred to other cluster members.

Q) Types of session replication:
1.In-Memory:
Client first connects to a server and that server becomes the primary server. The primary server then copies the data on to a server and the other cluster members fetches the session data from that server and also the other server keeps their session data on to that server and the primary server fetches that session data from that server, and, thus all the servers keep updated with the latest session data.
NOTE: This type of session replication is internally used by weblogic if we do not define below mentioned strategies.

2.Memory:
Session data is stored in the memory (cache). After restart the session data get lost.

3.Cookie:
Session data gets stored in the user's browser.

4.File:
This is File based session replication wherein the session data gets stored in an xml file.

5.JDBC:
The session data is stored in DB (i.e persistent store).

NOTE: 2,3,4,5 are defined inside weblogic.xml inside <session-descriptor> tag.

--------------------------------
Commonly known error:
--------------------------------
ERROR: Java.io.Not serializable Exception
REASON (can be):
A non serializable object inside HTTP session which is not replicating to other cluster members.

Q) MULTICASTINGs Vs UNICASTING
Here by Multicasting / Unicasting, servers in a cluster communicate with each other by sending heartbeats and indicates that they are alive. For this communication between the servers, either unicast or multicast messaging is used.

This is choosen from the admin console:
Cluster> Configuration> Messaging > Messaging mode

MULTICASTING :
1.This is one to many type of communication, wherein, the cluster members sends their heartbeat messages to all other members in the cluster.
2.Multicast address and multicast port is required.
3.This often results into network latency.

UNICASTING:
1.This is one to one type of communication, wherein, one leader is elected among the cluster members and the cluster members send their heartbeat messages "one to one" to this leader and it polling (updating) the other members one by one.
2.Here NETWORK CHANNEL (NIC) is required for communication.
3.This never results into network latency.

--------------------------------
Commonly known error:
--------------------------------
ERROR: Multicast<Critical subsystem cluster has failed. Setting server state to FAILED.

REASON:Unable to receive set of multicast messages

SOLUTION:
1. Multicast port must be properly defined.
2. Use the debug flags (debug cluster, debug cluster Heartbeats) and then check the logs.
3. Run the multicast test (not at the top of my head as of now).

ERROR: <BEA-003108> <Unicast receive error:java.io.EOF Exception>
SOLUTION: Make sure that NIC is functioning properly with your network team.

Q) DIFFERENCE BETWEEN WLS8 AND LATER VERSIONS:

WEBLOGIC8:
1.Here connection pool and multipool was there and we needed to target explictly on the datasource.
2.Supports only Multicasting .
3.Execute queues was there.
4.config.xml was large which contains the information related to JMS, JDBC inside it.
5.No Lock&Edit feature was available.

WEBLOGIC9 ONWARDS:
1.Here data source and multi datsource are in use.
2.This supports unicasting and multicasting as well for backward compatibility.
3.Workmanagers in place of execute queues.
4.Here config.xml is divided into there config file:
jdbc-config.xml, jms-config.xml, xonfig.xml
5.Lock&Edit feature is avaailable.

Q) CONNECTION CAN EITHER BE IN FOLLOWING ONE OF THE STATES:
1.Listen
2.Establish
3.Closed
4.Closed_wait

Q) LOGGING LEVELS:
1.Info
2.Debug
3.Warning
4.Critical
5.Error

Q) jrcmd Commands Taking Heap and Thread dumps
...\jrockit_jdk\bin\jrcmd -->List all JRockit JVM processes running on the machine
...\jrockit_jdk\bin\jrcmd <PID> print_threads -->Take thread dumps
...\jrockit_jdk\bin\jrcmd <PID> print_memusage -->Print Memory Usage
...\jrockit_jdk\bin\jrcmd <pid> hprofdump filename=/tmp/jrockit1.hprof -->Take Heap Dump
...\jrockit_jdk\bin\jrcmd <pid> heap_diagnostics -->Analyse biggest/culprit java classes

Q) WLS VERSIONS AND SUPPORTED O.S AND JDK VERSIONS:

WLS10.3.5.0--> Sun JDK 1.6.0_24+ & RHEL5

Version Packs Name Supported JDKs versions Supported Linux versions
WLS 8 Service pack (SP) JDK 1.4 RHEL3,4
WLS 9 Maintanance pack (MP) JDK1.4 and 1.5 RHEL3,4,5
WLS 10 Maintanance pack (MP) JDK 1.5 and 1.4 RHEL4,5
WLS 11 Patchset JDK 1.6 RHEL4,5

WLS10G
WLS10.0.1= 10.0 MP1
WLS10.0.2= 10.0 MP2

WLS 11G
WLS10.3.0.0 (Baseversion)
WLS 10.3.1.1 (Patchset0)
WLS 10.3.1.2 (Patchset1)
WLS 10.3.1.3 (Patchset2)
WLS 10.3.1.4 (Patchset3)
WLS 10.3.1.5 (Patchset4)
WLS 10.3.1.6 (Patchset5)

Q) DIFFERENCE BETWEEN DEVELOPMENT AND PRODUCTION MODE

Development mode:
The default JDK for development domain is Sun Hotspot
You can use the demo certificates for SSL
Auto deployment is enabled
Server instances rotate their log files on startup
Admin Server uses an automatically created boot.properties during startup
The default maximum capacity for JDBC Datasource is 15
The debugFlag which is used to start the WebLogic Workshop Debugger is enabled

Production mode:
The default JDK for production domain is JRockit
If you use the demo certificates for SSL a warning is displayed
Auto deployment is disabled
Server instances rotate their log files when it reaches 5MB
Admin Server prompts for username and password during startup
The default maximum capacity for JDBC Datasource is 25
The debugFlag which is used to start the WebLogic Workshop Debugger is disabled.

Q )MODES OF DEPLOYMENT

Stage mode:
The Administration Server copies the archive files from their source location to a location on each of the targeted Managed Servers that deploy the archive. For example, if you deploy a J2EE Application to three servers in a cluster, the Administration Server copies the application archive files to each of the three servers. Each server then deploys the J2EE Application using its local copy of the archive files.
Stage mode is the default mode when deploying to more than one WebLogic Server instance.

Nostage mode:
The Administration Server does not copy the archive files from their source location. Instead, each targeted server must access the archive files from a single source directory for deployment. For example, if you deploy a J2EE Application to three servers in a cluster, each server must be able to access the same application archive files (from a shared or network-mounted directory) to deploy the application.
Nostage mode is the default mode when deploying only to the Administration Server (for example, in a single-server domain). You can also select nostage mode if you run a cluster of server instances on the same machine.

External_stage mode:
External_stage mode is similar to stage mode, in that the deployment files must reside locally to each targeted server. However, the Administration Server does not automatically copy the deployment files to targeted servers in external_stage mode; instead, you must manually copy the files, or use a third-party application to copy the files for you.

Q) JDBC (JAVA DATABASE CONNECTIVITY) Interview Questions
The JDBC contains 2 important topics- Connection Pool and Datasource.

-------------------------------
CONNECTION POOL:
-------------------------------
A connection pool contains a group of JDBC connections which can be readily used by the applications.
These JDBC connections are created when the connection pool is registered, usually when starting up weblogic server.
The application borrows a connection from the connection pool, uses it, then returns it to connection pool by closing it.

Click on weblogic console L.H.S > JDBC > Now you need to feed DB name, DB username and password, Driver name and below mentioned JDBC parameters. Also, if we select
the correct values as per our application's need, then this will tune the application's performance to optimum level.

-------------------------
JDBC known errors:
-------------------------
Generally we see the following type of errors while dealing with JDBC issues:
<Warning> <JDBC> <BEA-001129> <Received exception while creating connection for pool "myds1": ORA-00257: archiver error. Connect internal only, until freed.>

The errors require optimum tuning of JDBC parameters.

JDBC TUNING PARMETERS:
--------------------------------
1.INITIAL CAPACITY:
--------------------------------
The number of physical database connections to create when creating the connection pool.

VALUE CONSTRAINTS:-
Minimum: 0
Maximum: 214,74,83647
Default: 1
Dynamic: yes

----------------------------
2Minimum Capacity:
----------------------------
The minimum number of physical connections that this connection pool can contain after it is initialized.
Minimum value: 0
Maximum value: 2147483647

---------------------------
3.Maximum Capacity:
----------------------------
Maximum number of physical database connections that this connection pool can contain. Different JDBC Drivers and database servers may limit the number of possible physical connections.

Set the Maximum Capacity of the connection pool at least equal to the Execute Thread Count.
The MaxCapacity attribute of the JDBCConnectionPool element allows to set the maximum number of physical database connections that a connection pool can contain.
Different JDBC drivers and database servers might limit the number of possible physical connections.
In production, it is advisable that the number of connections in the pool equal the number of concurrent client sessions that require JDBC connections

VALUE CONSTRAINTS:-
Minimum: 1
Maximum: 214,74,83,647
Default: 15
Dynamic: yes

NOTE:
**set Initial Capacity equal to Maximum Capacity.
**If InitialCapacity is less than MaxCapacity, the server then needs to create additional database connections when its load is increased

-----------------------------
4.Capacity Increment:
-----------------------------
Increment by which the connection pool capacity is expanded. When there are no more available physical connections to service requests, the connection pool will create this number of additional physical database connections and add them to the connection pool. The connection pool will ensure that it does not exceed the maximum number of physical connections as set by MaxCapacity.

VALUE CONSTRAINTS:-
Minimum: 1
Maximum: 2147483647
Default: 1
Dynamic: yes

------------------------------------------------
5.Statement Cache Type: (NOT Imp)
------------------------------------------------
The algorithm used to maintain the statement cache:
LRU - After the statementCacheSize is met, the Least Recently Used statement is removed when a new statement is used.
FIXED- The first statementCacheSize number of statements is stored and stay fixed in the cache. No new statements are cached unless the cache is manually cleared.

**Select the least-recently-used (LRU) algorithm for the cache; this removes rarely-used statements from the cache.

**Use the statement cache to improve performance of prepared and callable statements.
The prepared statement cache keeps compiled SQL statements in memory, thus avoiding a round-trip to the database when the same statement is used later.

VALUE CONSTRAINTS:-
Default: LRU
Valid values:
LRU
FIXED
Dynamic: no

--------------------------------------------
6.Statement Cache Size: (Not imp)
--------------------------------------------
The number of Prepared and Callable Statements stored in the cache for further use. WebLogic Server can reuse statements in the cache without reloading them, which can increase server performance. Setting the size of the statement cache to 0 turns it off. Each connection in the pool has its own cache of statements.

VALUE CONSTRAINTS:-
Default: 10
Dynamic: yes

**************************ADVACEDOPTIONS:************************

--------------------------
7.Shrink Frequency:
--------------------------
Number of seconds to wait before shrinking a connection pool that has incrementally increased to meet demand. ShrinkingEnabled must be set to true for a connection pool to shrink.

VALUE CONSTRAINTS:-
Units: seconds
Minimum: 0
Maximum: 2147483647
Default: 900
Dynamic: yes

------------------------
8.Allow Shrinking:
------------------------
Indicates whether or not the pool can shrink back to its InitialCapacity when it is detected that connections created during increased traffic are not being used.
When shrinking, the number of connections is reduced to the greater of either the initial capacity or the current number of connections in use.

VALUE CONSTRAINTS:-
Default: true
Valid values:true/ false
Dynamic: yes

------------------------------------------------
9.Enable Connection Leak Profiling:
------------------------------------------------
Specifies that JDBC Connection leak profiling information is gathered.
A Connection leak occurs when a connection from the pool is not closed explicitly by calling close() on that connection.

When connection leak profiling is active, the connection pool will store the stack trace at the time the Connection object is allocated from the connection pool and given to the client. When a connection leak is detected (when the Connection object is garbage collected), this stack trace is reported.

This option is required to view leaked connections from the connection pool (right-click the connection pool name and select View Leaked Connections).

This feature uses extra resources and will likely slow down connection pool operations, so it is not recommended for production use.

**The connection leak profiling option shows leaked connections from the connection pool. BEA recommends that you do not use this option in production; it uses extra resources and typically slows connectionpool operations.

VALUE CONSTRAINTS:-
Default: false
Dynamic: yes

-----------------------
10.Test Frequency:
-----------------------
The number of seconds between database connection tests. After every TestFrequencySeconds interval, unused database connections are tested using TestTableName.
Connections that do not pass the test will be closed and reopened to re-establish a valid physical database connection. If the test fails again, the connection is closed.

If TestTableName is not set, the test will not be performed.

If set to 0 (the default), connections are not tested.

**If database is restarted when WebLogic Server is running, Test Frequency can be increased from 0, so that all the connections are closed and reopened to re-establish valid physical connection. After all the connections are recreated changing it back to 0 will disable the testing.

VALUE CONSTRAINTS:-
Units: seconds
Minimum: 0
Maximum: 2147483647
Default: 0
Dynamic: yes

---------------------------------------
11.Test Reserved Connections:
---------------------------------------
When selected (set to true), WebLogic Server tests a connection before giving it to the client. The test adds a small delay in serving the client's request for a connection from the pool, but ensures that the client receives a working connection (assuming that the DBMS is available and accessible).

The attribute TestTableName must be enabled for TestConnectionsOnReserve to be effective.

This attribute is required for connection pools used within a MultiPool that uses the High Availability algorithm.

**Use Test Reserved Connections only if you can afford the overhead of testing connections as part of normal request processing.

VALUE CONSTRAINTS:-
Default: false
Dynamic: yes

------------------------------------------
12.Connection Reserve Timeout:
------------------------------------------
This is the time out in seconds in which weblogic will call the CONNECTION POOL to reserve a CONNECTION.
When set to 0, a call will never timeout.
When set to -1, a call will timeout immediately.

VALUE CONSTRAINTS:-
Units: seconds
Minimum: -1
Maximum: 2147483647
Default: 10
Dynamic: yes

------------------------------------------------------
13.Connection Creation Retry Frequency:
------------------------------------------------------
This the time (in seconds) after which weblogic tries to connect to DATABASE to create a connection.

If you do not set this value, connection pool creation fails if the database is unavailable. If set and if the database is unavailable when the connection pool is created, WebLogic Server will attempt to create connections in the pool again after the number of seconds you specify, and will continue to attempt to create the connections until it succeeds. When set to 0 (the default), this feature is disabled.

**Connection Creation Retry Frequency can be used to retry for establishing connections to the database, if database is not reachable when creating connection pool or starting WebLogic Server.

VALUE CONSTRAINTS:-
Units: seconds
Minimum: 0
Maximum: 2147483647
Default: 0
Dynamic: yes

------------------------------------------
14.Inactive Connection Timeout:
------------------------------------------
The number of seconds of inactivity after which reserved connections will forcibly be released back into the pool. When set to 0 (the default), this feature is disabled.
i.e Configure Inactive Connection Timeout to specify how long (in seconds) a connection can be inactive before it is reclaimed to the pool.

VALUE CONSTRAINTS:-
Units: seconds
Minimum: 0
Maximum: 2147483647
Default: 0
Dynamic: yes

---------------------------
15.Test Table Name:
---------------------------
The name of the table used when testing a physical database connection. The default SQL code used to test a connection is
"select count(*) from TestTableName"
**Avoid using a production table for “Test Table Name”, use a dummy table (ex. dual).

VALUE CONSTRAINTS:-
Dynamic: no

USE:
http://middlewaremagic.com/weblogic/?p=586

-----------------------------------------------------------------------

---------------
Datasource:
---------------
Click on weblogic console L.H.S > JDBC > Datasources > now feed:
>NAME- Name of JDBC Datasource

>JNDI Name- Enter JNDI absolute path to where this JDBC datasource will be bound.
NOTE: You can specify multiple names seperated by semi-colons (;)

>**CONNECTION POOL- Select the connection pool to which the datasource will point. Application gets the connection from the underlying connection pool by looking up the datasource on the JNDI tree and then requesting a connection from the datasource. The pool you select will be used to provide the connection when application requests for a connection from this datasource.

>**Select the servers and clusters on which you want to deploy the new datasource. You should deploy the datasource to the same servers and cluster on which the underlying connection pool is deployed.

-----------------------------------------------------------------------

Q) JDBC Thin Drivers?
Ans: These are pure java drivers.
>This is a type4 driver
>This is easy to install
>It is used if java applets are being used
>This driver must be used until and unless there is some specific requirement of the application team.

These are pure java drivers i.e thin drivers i.e This driver directly converts the java statements to SQl Statements . It wont convert to JDBC statement.
>This is easy to install
>It is used if java applets are being used
>This driver must be used untill and unless there is some specific requirement of the application team.

FLOW:
JAVA--->SQLStatement--->Database(s)

EXAMPLE-
-WebLogic jDrivers for Microsoft SQL Server
-Third-party drivers, including- Oracle Thin and Oracle Thin XA drivers

Q) How to add 3rd party drivers with Weblogic?
Ans: There are 2 ways to do this:
1.Here we need to put the required 3rd party JDBC driver's librarires and jars inside: WL_HOME\server\lib along with weblogic.jar, so that they are loaded when weblogic.jar is loaded (when the server starts). Therefore, NOW, you DO NOT need to add these JDBC drivers to your CLASSPATH + Install the driver on Weblogic console.
2.If you plan to use a third-party JDBC driver that is not installed with WebLogic Server then here:
You must install the driver on weblogic console + Update your CLASSPATH with the absolute path of of your driver files (i.e driver's libraries and jars) + PATH with the absolute path of database client files i.e DB client's executables files (i.e .bin/ .exe etc)

Q) Difference between CLASSPATH and PATH?
Ans: CLASSPATH contains the absolute path of the required libraries and jars while the PATH contains the absloute path of required executable file like .bin/ .exe etc.

Q) Difference between XA and non-XA drivers?
Ans:
A non-XA transaction always involves just one resource (local transaction).
NOTE: Most stuff in the world is non-XA - a Servlet or EJB or plain old JDBC in a Java application talking to a single database.

XA= Global transaction ( i.e that may span across multiple resources within one single transaction)
NOTE:
XA gets involved when you want to work with multiple resources - 2 or more databases, a database and a JMS connection, all of those plus maybe a JCA resource - all in a single transaction. In this scenario, you'll have an app server like Websphere or Weblogic or JBoss acting as the Transaction Manager, and your various resources
(Oracle, Sybase, IBM MQ JMS, SAP, whatever) acting as transaction resources. Your code can then update/delete/publish/whatever across the many resources. When you say "commit", the results are commited across all of the resources. When you say "rollback", _everything_ is rolled back across all resources.

Q ) Node Manager
Node manager is a weblogic server utility that enables you to start, shut down, and restart administration server and managed server instances from a remote location (weblogic console).
There are two types of Node manager . 1)Java-Based Node manager 2)Script-Based Node manager.
Java-Based Node manager:
Java-based Node manager runs within a Java Virtual Machine (JVM) process.
It is recommended that you run it as a Windows server and VBox UNIX platforms.
Script-Based Node manager:
For UNIX and Linux systems, Weblogic Server provides a script-based version of Node manager.

The following are the important configuration files is Node manager.

Nodemanager.properties:
This is the configuration file used by the Java-based version of Node manager.
This file is located in WL_HOME/common/nodemanager.

startup.properties:
Each Managed server instance has its own startup.properties file with properties that control how Nodemanager starts up and controls the server.
Nodemanager automatically creates this file by using properties passed to Nodemanager when the
Administration Server was last used to start the server.
This allows a Nodemanager client or startup scripts to restart a Managed server using the same
properties last used by the Administration Server.

Nodemanager.domains:
This file contains mappings between the names of domains managed by Nodemanager and their corresponding directories.
This file is located in WL_HOME/common/nodemanager.

nm_data.properties:
This file stores the encryption data the Nodemanager uses as a symmetric encryption key.
This file is located in WL_HOME/common/nodemanager.

nm_password.properties:
This file stores the Nodemanager username and password.
This file is located in DOMAIN_HOME/config/nodemanager.
boot.properties:
Nodemanager uses this file to specify user credentials when starting a server.
This file is located in DOMAIN_HOME/servers/server_name/data/nodemanager.

Node Manager: Common Problems and Resolutions
--------------------------------------------------------
Error: NodeManager is not reachable issue:
--------------------------------------------------------
see: http://middlewaretimes.blogspot.in/2014/02/nodemanager-not-reachable.html
STEPS to start Admin server using Node manager via WLST:
--------------------------------------------------------------------------------
1. Set the java environment using SetDomainEnv.sh
2. java weblogic.WLST
3.nmConnect('weblogic','weblogic','localhost','5556','7001_Domain')
4.nmStart('AdminServer')
5.nmServerStatus('AdminServer')

Q) HTTP TUNNELING:
Http tunneling is encapsulating other protocols within http protocol.
Usually done when you need to go through a firewall because it only lets http to go through.

Commonly known error:
ERROR: HTTP Client Login: Login rejected with code: 'failed',
REASON: java.net.rjvm.http.HTTPserverJVMConnection.acceptJVM Connection.
CAUSE: If you are trying to access WLS admin console via SSH tunnel OR through network interface that the admin server is NOT listening on, then, weblogic will throw this exception. SOLUTION: Enable http tunneling through console by setting the 'Admin server'> Click on Protocol Tab > Click on Https sub tab.few Debug parameters:

DebugHttp
DebugHttpLogging
DebugtunnelingConnection

Http tunneling is encapsulating other protocols within http protocol.
Usually done when you need to go through a firewall because it only lets http to go through.

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. However, you can expect some performance loss in comparison to a normal socket connection.

Configuring the HTTP Tunneling Connection
Under the HTTP protocol, a client may only make a request, and then accept a reply from a server. The server may not voluntarily communicate with the client, and the protocol is stateless, meaning that a continuous two-way connection is not possible.

WebLogic HTTP tunneling simulates a T3Connection via the HTTP protocol, overcoming these limitations. There are two attributes that you can configure in the Administration Console to tune a tunneled connection for performance. It is advised that you leave them at their default settings unless you experience connection problems. These properties are used by the server to determine whether the client connection is still valid, or whether the client is still alive.

Note:
>HTTP tunneling is disabled by default.
>The server must also support both the HTTP and T3 protocols in order to use HTTP tunneling.

Tunneling Client Ping
When an HTTP tunnel connection is set up, the client automatically sends a request to the server, so that the server may volunteer a response to the client. The client may also include instructions in a request, but this behavior happens regardless of whether the client application needs to communicate with the server. If the server does not respond (as part of the application code) to the client request within the number of seconds set in this attribute, it does so anyway. The client accepts the response and automatically sends another request immediately.

Default is 45 seconds; valid range is 20 to 900 seconds.

Tunneling Client Timeout
If the number of seconds set in this attribute have elapsed since the client last sent a request to the server (in response to a reply), then the server regards the client as dead, and terminates the HTTP tunnel connection. The server checks the elapsed time at the interval specified by this attribute, when it would otherwise respond to the client's request.

Default is 40 seconds; valid range is 10 to 900 seconds.

JMS (Java Messaging Service)
This is used for ASYNCHRONOUS Communication.

JMS Server:
A JMS server acts as a management container for resources within JMS modules. Some of its responsibilities include the maintenance of persistence and state of messages and subscribers. A JMS server is required in order to create a JMS module.

JMS Module:
A JMS module is a definition which contains JMS resources such as queues and topics.

Queues and Topics:
Are the modes of communication i.e one to one and one to many respectively.

Subdeployment:
A subdeployment is a mechanism by which JMS module resources (such as queues, topics, and connection factories) are grouped and targeted to a server resource (such as JMS servers, server instances, SAF agents, or a cluster). This called advanced targeting.

Connection Factory:
A connection factory is a resource that enables JMS clients to create connections to JMS destinations. (This allows JMS clients to connect to JMS destinations)

STEPS OF CREATION:

1. Create a JMS Server
Services > Messaging > JMS Servers
TARGET: Managed server/ Cluster

2. Create a JMS Module
Services > Messaging > JMS Modules
TARGET:JMS module is targetted on a JMS server.
NOTE: While we create a JMS module, it asks for-- “Would you like to add resources to this JMS system module” unchecked/checked, and then press Finish .

3. Create a JMS Queue/ Topic
Services > Messaging > JMS Modules
TARGET:
Stand-alone queues and topics ONLY JMS server
Distributed queues and topics Subdeployment

4.Create Subdeployment
Services > Messaging > JMS Modules
TARGET: Managed server/ cluster/ JMS server (Banjara)

5. Create a Connection Factory
Services > Messaging > JMS Modules
TARGET:
FOR DEFAULT TARGETING Managed server or cluster and not on Subdeployment (as per ORACLE recommendations)
FOR ADVANCED TARGETING Subdeployment.

NOTE:

JMS servers are targetted to either- JMS servers/ Managed servers/ Cluster.
These JMS servers acts as management containers for Topics and queues. A JMS server's primary responsibility is to maintain the information (persistent messages) that arrive on destination.
STANDALONE queues/ Topics can ONLY be targeted to a single JMS server.... Whereas... connection factories, foreign servers can be targeted to more than one JMS servers OR to more than one managed server OR a cluster.

JMS SAF (JMS Store and Forward agent):
WLS SAF service is used to provide highly available JMS message production.

Few debug parameters related to JMS:

Debug JMSBackEnd/ DebugJMSFrontEnd
DebugJMSBoot
DebugJMSModule

JMS Modules are of 2 types:
1.System module (Weblogic admin can create this)
2.Application module (This is created by application team)

NOTE:
Application team decides that JMS module will be of which type - System or Application.

LOG FILE AND OUT FILE:

OUT FILE:
> .out file is generated everytime the server is restarted.
> .out file contains less logging as compared to .log file.
> .out file contains the standard output.

LOG FILE:
> Log file is not generated everytime the server is retsarted.
> Application logging goes inside the .log file

Q) PLUGIN WITH WEBLOGIC
see more : http://middlewaretimes.blogspot.in/2014/03/oracle-weblogic-server-how-to-configure.html
-------------------------------------------------------------
Configuring the Apache HTTP Server Plug-In:
-------------------------------------------------------------

After installing the plug-in in the Apache HTTP Server, configure the WebLogic Server Apache Plug-In and configure the server to use the plug-in. This section explains
how to edit the Apache httpd.conf file to instruct the Apache server to load the WebLogic Server library for the plug-in as an Apache module, and to specify the
application requests that should be handled by the module.

Editing the httpd.conf File

Edit the httpd.conf file in your Apache HTTP server installation to configure the Apache HTTP Server Plug-In.

This section explains how to locate and edit the httpd.conf file, to configure the server to use the WebLogic Server Apache Plug-In, to proxy requests by path or by
MIME type, to enable HTTP tunneling, and to use other WebLogic Server plug-in parameters.

Open the httpd.conf file.
The file is located at APACHE_HOME\conf\httpd.conf (where APACHE_HOME is the root directory of your Apache HTTP server installation). See a sample httpd.conf file at
Setting Up Perimeter Authentication.

Ensure that the WebLogic Server modules are included for Apache 2.0.x, manually add the following line to the httpd.conf file:
LoadModule weblogic_module modules\mod_wl_20.so
Add an IfModule block that defines one of the following:
For a non-clustered WebLogic Server:

The WebLogicHost and WebLogicPort parameters.

For a cluster of WebLogic Servers:

The WebLogicCluster parameter.

For example:

<IfModule mod_weblogic.c>
WebLogicHost myweblogic.server.com
WebLogicPort 7001
</IfModule>
To proxy requests by MIME type, add a MatchExpression line to the IfModule block. Note that if both MIME type and proxying by path are enabled, proxying by path takes
precedence over proxying by MIME type.
For example, the following IfModule block for a non-clustered WebLogic Server specifies that all files with MIME type .jsp are proxied:

<IfModule mod_weblogic.c>
WebLogicHost myweblogic.server.com
WebLogicPort 7001
MatchExpression *.jsp
</IfModule>
You can also use multiple MatchExpressions, for example:

<IfModule mod_weblogic.c>
WebLogicHost myweblogic.server.com
WebLogicPort 7001
MatchExpression *.jsp
MatchExpression *.xyz
</IfModule>
If you are proxying requests by MIME type to a cluster of WebLogic Servers, use the WebLogicCluster parameter instead of the WebLogicHost and WebLogicPort parameters.
For example:

<IfModule mod_weblogic.c>
WebLogicCluster w1s1.com:7001,w1s2.com:7001,w1s3.com:7001
MatchExpression *.jsp
MatchExpression *.xyz
</IfModule>
To proxy requests by path, use the Location block and the SetHandler statement. SetHandler specifies the handler for the Apache HTTP Server Plug-In module. For
example the following Location block proxies all requests containing /weblogic in the URL:
<Location /weblogic>
SetHandler weblogic-handler
PathTrim /weblogic
</Location>
The PathTrim parameter specifies a string trimmed from the beginning of the URL before the request is passed to the WebLogic Server instance (see General Parameters
for Web Server Plug-Ins).

Optionally, enable HTTP tunneling for t3 or IIOP.
To enable HTTP tunneling if you are using the t3 protocol and weblogic.jar, add the following Location block to the httpd.conf file:
<Location /HTTPClnt>
SetHandler weblogic-handler
</Location>
To enable HTTP tunneling if you are using the IIOP, the only protocol used by the WebLogic Server thin client, wlclient.jar, add the following Location block to the
httpd.conf file:
<Location /iiop>
SetHandler weblogic-handler
</Location>
Define any additional parameters for the Apache HTTP Server Plug-In.
The Apache HTTP Server Plug-In recognizes the parameters listed in General Parameters for Web Server Plug-Ins . To modify the behavior of your Apache HTTP Server
Plug-In, define these parameters either:

In a Location block, for parameters that apply to proxying by path, or
In an IfModule block, for parameters that apply to proxying by MIME type.
Including a weblogic.conf File in the httpd.conf File

If you want to keep several separate configuration files, you can define parameters in a separate configuration file called weblogic.conf file, by using the Apache
Include directive in an IfModule block in the httpd.conf file:

<IfModule mod_weblogic.c>
# Config file for WebLogic Server that defines the parameters
Include conf/weblogic.conf
</IfModule>
The syntax of weblogic.conf files is the same as that for the httpd.conf file.

This section describes how to create weblogic.conf files, and includes sample weblogic.conf files.

Some imp parameters:

Idempotent (default ON)
When set to ON and if the servers do not respond within WLIOTimeoutSecs, the plug-in fail over. If set to OFF the plug-in do not fail over If you are using the Netscape Enterprise Server Plug-In, or Apache HTTP Server you can set this parameter differently for different URLs or MIME types.

DynamicServerList (default ON)
WebLogicCluster is only a starting point for the dynamic server list that the server and plug-in maintain This server list is dynamically updated for every request If set to OFF: The plug-in only uses the static list specified with the WebLogicCluster parameter If one or more servers in the static list fails, the plug-in could waste time trying to connect to a dead server, resulting in decreased performance. If you add a new server to the cluster, the plug-in cannot proxy requests to the new server unless you redefine this parameter. WebLogic Server automatically adds new servers to the dynamic server list when they become part of the cluster.
See more at:
http://middlewaremagic.com/weblogic/?p=654#sthash.99J7B6Dc.dpuf

ConnectTimeoutSecs (default 10 seconds)
Maximum time in seconds that the plug-in should attempt to connect to the WebLogic Server host. Make the value greater than ConnectRetrySecs
If ConnectTimeoutSecs expires without a successful connection, even after the appropriate retries (see ConnectRetrySecs), an HTTP 503 (Service Unavailable) response is sent to the client.

ConnectRetrySecs (default 2 seconds)
Interval in seconds that the plug-in should sleep between attempts to connect to the WebLogic server host ConnectRetrySecs <= ConnectTimeoutSecs
To specify no retries, ConnectRetrySecs = ConnectTimeoutSecs (but the plug-in always attempts to connect at least twice)

KeepAliveSecs (default 20)
The length of time after which an inactive connection between the plug-in and WebLogic Server is closed. You must set KeepAliveEnabled to true (ON when using the Apache plug-in) for this parameter to be effective
The value of this parameter must be less than or equal to the value of the Duration field set in the Administration Console on the Server/HTTP tab, or the value set on the server Mbean with the KeepAliveSecs attribute.

KeepAliveEnabled (default ON)
Enables pooling of connections between the plug-in and WebLogic Server.
Valid values for the Apache plug-in are ON and OFF.

WLIOTimeoutSecs (default 300 seconds)
Also known as HungServerRecoverSecs (old name)
Defines the amount of time the plug-in waits for a response to a request from WebLogic Server
The plug-in waits for WLIOTimeoutSecs for the server to respond and then declares that server dead, and fails over to the next server
The value should be set to a very large value. If the value is less than the time the servlets take to process, then you may see unexpected results

USE:
See more at: http://middlewaremagic.com/weblogic/?p=654#sthash.99J7B6Dc.dpuf

--------------------------------------
Q) Iplanet plugin configuration :
--------------------------------------

Step 1). Create a Webserver running on port 8081 using the Admin Console of SunOne.

Step 2). Copy over the plugin present in the following directory
C:\bea103\wlserver_10.3\server\plugin\win\32\proxy61.dll

To the Sun One Installation Directory

C:\Sun\WebServer6.1\plugins\lib

Step 3). Load the plugins by adding the following lines in magnus.conf present in
C:\Sun\WebServer6.1\https-testserver\config

magnus.conf

Init fn=”load-modules” funcs=”wl_proxy,wl_init” shlib=”C:/Sun/WebServer6.1/plugins/lib/
proxy61.dll”

To forward request to a Standalone Server add the following lines to obj.conf file present in
the following directory
C:\Sun\WebServer6.1\https-testserver\config

obj.conf
Service fn=”wl_proxy” WebLogicHost=localhost WebLogicPort=7001 WLLogFile=”C:/Sun/

WebServer6.1/https-testserver/logs/proxy.log” Debug=ALL DebugConfigInfo=ON

To forward request to a CLuster we need to add the following in the bj.conf file
Service fn=”wl_proxy” WebLogicCluster=”localhost:7001,localhost:7003? WLLogFile=”C:/

Sun/WebServer6.1/https-testserver/logs/proxy.log” Debug=ALL DebugConfigInfo=ON

Note:
http://weblogic-wonders.com/weblogic/2010/11/12/configuring-sunone-iplanet-webserver-with-weblogic/
http://docs.oracle.com/cd/E23943_01/web.1111/e16435/iplanet.htm

----------------------------------------------------
Proxy requests by URL (inside iPlanet)):
----------------------------------------------------
## -------------BEGIN SAMPLE obj.conf CONFIGURATION-------------------
# (using a WebLogic Cluster)
#
# Configure which types of HTTP requests should be handled by the
# iPlanet module (and, in turn, by WebLogic). This is done
# with one or more "<Object>" tags as shown below.
# Here we configure the iPlanet module to pass requests for
# "/weblogic" to a cluster of WebLogic Servers.
<Object ppath="*/weblogic/*">
Service fn=wl-proxy WebLogicCluster="myweblogic.com:7001,yourweblogic.com:7001, theirweblogic.com:7001" PathTrim="/weblogic"
</Object>
# Here we configure the plug-in so that requests that
# match "/servletimages/" are handled by the
# plug-in/WebLogic.
<Object name="si" ppath="*/servletimages/*">
Service fn=wl-proxy WebLogicCluster="myweblogic.com:7001,yourweblogic.com:7001, theirweblogic.com:7001"
</Object>
## ----------------END OF SAMPLE obj.conf CONFIGURATION------------------
Proxy requests by MIME types
# This Object directive works by file extension rather than
# request path. To use this configuration, you must modify the existing line or add the following line to mime.types file.:
## -----------------BEGIN SAMPLE mime.types FILE -------------------------
# type=text/jsp exts=jsp
#
## --------------------END SAMPLE mime.types------------------------------

## -------------BEGIN SAMPLE obj.conf CONFIGURATION-----------------------
# This configuration means that any file with the extension
# ".jsp" is proxied to WebLogic. Then you must add the
# Service line for this extension to the Object "default",
# which should already exist in your obj.conf file:
<Object name=default>
NameTrans fn=pfx2dir from=/ns-icons dir="c:/Export/Home/ns-icons"
NameTrans fn=pfx2dir from=/mc-icons dir="c:/Export/Home/ns-icons"
NameTrans fn="pfx2dir" from="/help" dir="c://Export/Home/manual/https/ug"
NameTrans fn=document-root root="c://Export/Home/docs"
Service method="(GET|HEAD|POST|PUT)" type=text/jsp fn=wl_proxy WebLogicCluster="myweblogic.com:7001, yourweblogic.com:7001,
theirweblogic.com:7001",PathPrepend=/jspfiles
PathCheck fn=nt-uri-clean
PathCheck fn="check-acl" acl="default"
PathCheck fn=find-pathinfo
PathCheck fn=find-index index-names="index.html,home.html"
ObjectType fn=type-by-extension
ObjectType fn=force-type type=text/plain
Service method=(GET|HEAD) type=magnus-internal/imagemap fn=imagemap
Service method=(GET|HEAD) type=magnus-internal/directory fn=index-common
Service method=(GET|HEAD) type=*~magnus-internal/* fn=send-file
AddLog fn=flex-log name="access"
</Object>
# The following directive enables HTTP-tunneling of the
# WebLogic protocol through the NES plug-in.
<Object name="tunnel" ppath="*/HTTPClnt*">
Service fn=wl-proxy WebLogicCluster="myweblogic.com:7001, yourweblogic.com:7001, theirweblogic.com:7001"
</Object>
#
## -------------END SAMPLE obj.conf CONFIGURATION--------------------

------------------
Q) Plugin with iis:
------------------
This is a simple example of Configuring IIS(running on default port 80) on Weblogic Server. Create two Weblogic Servers running on Port 7001 and 7003, create a Cluster and add the two Servers to the Cluster. Deploy an application on the Cluster and after the configuration on ISS, access the application as
http://localhost/myApp
Step-1). Make a directory on the IIS box for the plug-in.
For instance: c:\Inetpub\WLS_IIS_Plugin\
Step-2). Copy iisforward.dll and iisproxy.dll to this new directory. These files are located at:
10.0: \wlserver_10.0\server\plugin\win\32
10.3: \wlserver_10.3\server\plugin\win\32
Step-3).To install iisforward.dll as an ISAPI filter, do the following:
a). Go to Start->Administrative Tools->Internet Information Services (IIS) Manager
b). In the left pane, go to the active website (like “Default Web Site”) Right-click the active website and select Properties
c). Select the ISAPI Filters tab and press the Add button Filter name: WLS IIS Plugin (Or whatever you want)
d). Executable: C:\Inetpub\WLS_IIS_Plugin\iisforward.dll (Or whatever path you created)
e). Press OK twice, IIS6 does not allow the iisforward.dll ISAPI Extension to run by default.
To enable:
In the left pane of the Internet Information Services (IIS) Manager,click on Web Service Extension (located under the computer name)
In the right pane, highlight All Unknown ISAPI Extensions and press
the Allow button
Step-4).To map .wlforward to use iisproxy.dll, do the following:
a). In the left pane, drill down to the active website (like “Default Web Site”)
b). Right-click the active website and select Properties
c). Select Home Directory tab
d). Click the Configuration… button.
e). In the Application Mapping tab, click the Add… button.
i). Executable: C:\Inetpub\WLS_IIS_Plugin\iisproxy.dll
ii). Extension: .wlforward
f). Uncheck Verify that file exists
g). IMPORTANT: Ensure .wlforward is *not* mapped to iisforward.dll. While this seems intuitive, it is wrong. .wlforward maps to iisproxy.dll.
h). Press OK three times
i). Exit the IIS Manager MMC console.
Step-5).Create a text file named iisproxy.ini and place it in the plug-in directory (e.g. c:\Inetpub\WLS_IIS_Plugin\iisproxy.ini)
“iisproxy.ini”
————————-
WebLogicCluster=localhost:7001,localhost:7003
WlForwardPath=/
Debug=ALL
DebugConfigInfo=ON
WLLogFile=c:/temp/iisproxy.log
————————-
Step-6).Restart IIS using the following CLI statement: iisreset /restart
Step-7).Use a browser to access IIS. This will ‘turn on’ the IIS->WLSISAPI filter.
Step-8).Relaunch the IIS Manager and check the ISAPI filter tab to ensure the iisforward.dll is now ‘turned on’, as evidenced by a green arrow.

Q) TOTAL NUMBER OF PORTS ON A PHYSICAL SERVER:
There are total 65536 ports ( 0 To 65535)

The port numbers are divided into three ranges:
1.The Well Known Ports- The Well Known Ports are those from 0 through 1023.
2.The Registered Ports- The Registered Ports are those from 1024 through 49151
3.The Dynamic and/or Private Ports- The Dynamic and/or Private Ports are those from 49152 through 65535

----------------------------------------------------------
Q) Well Known Port Numbers with description:
----------------------------------------------------------
1 TCP Port Service Multiplexer (TCPMUX)
5 Remote Job Entry (RJE)
7 ECHO
18 Message Send Protocol (MSP)
20 FTP -- Data
21 FTP -- Control
22 SSH Remote Login Protocol
23 Telnet
25 Simple Mail Transfer Protocol (SMTP)
29 MSG ICP
37 Time
42 Host Name Server (Nameserv)
43 WhoIs
49 Login Host Protocol (Login)
53 Domain Name System (DNS)
69 Trivial File Transfer Protocol (TFTP)
70 Gopher Services
79 Finger
80 HTTP
103 X.400 Standard
108 SNA Gateway Access Server
109 POP2
110 POP3
115 Simple File Transfer Protocol (SFTP)
118 SQL Services
119 Newsgroup (NNTP)
137 NetBIOS Name Service
139 NetBIOS Datagram Service
143 Interim Mail Access Protocol (IMAP)
150 NetBIOS Session Service
156 SQL Server
161 SNMP
179 Border Gateway Protocol (BGP)
190 Gateway Access Control Protocol (GACP)
194 Internet Relay Chat (IRC)
197 Directory Location Service (DLS)
389 Lightweight Directory Access Protocol (LDAP)
396 Novell Netware over IP
443 HTTPS
444 Simple Network Paging Protocol (SNPP)
445 Microsoft-DS
458 Apple QuickTime
546 DHCP Client
547 DHCP Server
563 SNEWS
569 MSN
1080 Socks

USE: http://www.webopedia.com/quick_ref/portnumbers.asp

PERFORMANCE TUNING(Jrockit JDK)
See : http://middlewaretimes.blogspot.in/2014/08/jvm-memory-monitoring-tuning-garbage.html
See: http://middlewaretimes.blogspot.in/2014/08/jvm-crash-javalangoutofmemoryerror.html

PERFORMANCE TUNING(Sun JDK):

OOM comes due to following issues:
1.Heap
2.Native
3.Perm Gen (If its Sun JDK) // TLA if it is JRockit
4.Due to large object
5.Swap space

NOTE:
Heap can be allocated at max at 75% of RAM.

------------
1.HEAP:
------------
If OOM comes due to heap space, then we need to increase the heap space (Xms and XMX values). It is always recommended as ORACLE's beat practice to keep both the Xms and Xmx at the same values. By allocating Xms= Xmx it ensures that the heap is reserved and no other process can interrupt in the heap space and the application has to wait till that process does not finish.

------------
2.Native:
------------
ERROR: java.lang.out of memory Error: Unable to create new Native thread.
SOLUTION:
1.Decrease the heap space.

2.Check for ulimit –a
ulimit and sysctl programs allow to limit system-wide resource use
ulimit -u 30 : this way we can set ulimit
ulimit -a : this lists current setting

If we see that there are too many open files, then we need to ask our UNIX team to increase the ulimit.

3.Set kernel parameter max dsize to a higher value by contacting your Unix team.

4.Need to reduce the JVM Stack Size and the O.S size both. Set the -Xss (i.e java stack size) in java options and set ulimit -S on O.S level by contacting your unix team.

-------------------------------------------
3.(A)Perm gen: (If it is Sun JDK)
-------------------------------------------
This is set to 1/3rd or 1/4th of the heap space as the ORACLE's best practices.

ERROR: java.lang.OutofMemory Error: Perm gen.
SOLUTION: Increase the max perm gen space i.e -xx:MaxPermSize=256m

There can be a leak in the perm gen objects. If tuning parameters do not resolve the issue, we need then need to use the memory leak detector tools and find out which instances in the perm gen space are not getting cleared.

Q) Example of memory leak detector tool and how to use it?
Ans:

-----------
(B)TLA:
-----------
ERROR: java.lang.outOfMemory Error: NativeGetNewTLA
SOLUTION: set and tune the TLA size (as XXtlasize:128)

----------------------------------------------------------
4.OOM can be due to large object allocation:
----------------------------------------------------------
ERROR: java.lang.OutOfMemoryError: allocLargeObjectArray -Object size:372032, Num elements:372012
SOLUTION: set the -XXlargeObjectlimit: 128k

---------------------------
5.Due to Swap space:
----------------------------
Swap space= 2 * Heap space (ORACLE's best practices)

WLS HANG:

WLS hang occurs due to one of the following mentioned reasons:
1.WLS trying to establish a connection with DB, but it is not happening.
2.Due to network outage.
3.Some thtread is holding an object, AND some other thread is trying to hold the same object, since the 1st thread is not releasing the lock, then in such scenarios appplication goes on a hung state.

In such scenarios we need to take the thread dump.

ERROR: Stuck threads
SOLUTION: Take thread dumps 5-7 sets in an interval of 8-12 seconds.

THREAD DUMP:
----------------------------------
How to take thread dump:
----------------------------------
In case of WLS hang or OOM we need to trace the threads and we need to take thread dumps. And for this we need to use the following command:
Kill -3 pid (5 to 7 sets in an interval of 10-12 seconds)

This dump will utomaticall go in .out file

Sequence of commands:
1) cp 1.out 2.out
2) >1.out (This will empty the existing 1.out file)
3) Now kill -3 pid (5 to 7 sets in an interval of 10-12 seconds)
4) cp 1.out 3.out
5) Now restart the WLS , so, a fresh .out gets generated

Commonly used tools used for thread dump analysis are:
1.Samurai
2.IBM thread dump analyzer

Here we need to download samurai.exe fike from internet and then we need to double click on it.
It will open up wherein we need to drag and drop the .out file.
Here we need to analyze the application related (i.e default threads) which is tuck and has got the lowest thread id.
Once we click on this thread (in tabular format area), it will take you to detail thread stack trace. This stuck thread which has the lowest thread id is the culprit
thread and we need to check this thread for root cause analyis. Also we need to send this thread dump to our application team.

Here we need to make it sure that the resources which are needed at runtime are available otherwise the thread will hang and thus WLS will hang.

-----------------------
Types of threads:
-----------------------
1.Muxer threads
2.Execute threads
3.Application/ Default threads

1.Muxer threads:
Are socket related threads and these are always busy in accepting the requests which are coming to WLS and replying the same request.

2.Execute threads:
These are WLS threads which are used for processing the requests. We generally do not analyze them.

3.Application/ Default threads:
These are the threads which we analyze.

GARBAGE COLLECTION:
There are 2 Strategies of Garbage collection:

------------------------------------
1.Concurrent and GenCon:
------------------------------------
>>Concurrent= Full G.C happens AND the application stops for few milli seconds.
>>Generational Concurrent= G.C in Young Generation + FULL G.C AND the application stops for few milli seconds.

-----------------------------
2.Parallel and GenPar:
-----------------------------
>>Parallel= Full G.C happens AND the application does not stop.
>>Generational Parallel= G.C in Young Generation + FULL G.C AND the application does not stops.

Q) Where to Define these startegies?
Ans-inside JAVA Options

Q) By default which startegy is taken by JVM
AnsThere is no by default strategy.
JVM by default invokes GC by itself and invokes the strategy which is defined inside JAVA options ( i.e either inside startup script or setDomainEnv.sh or setWlsEnv.sh )
GC algorithms are- like Mark&Sweep, wherein the objects which are no longer in use are moved from YOUNG generation to OLD generation.

Q) Where to define?
Ans- inside java options

Q) How to trigger GC?
Ans-
1.(Forcefull) GC via Weblogic console.login to admin console
2. On left hand side, select Environment -> your server for which you want to perform GC
3. On right hand side select Monitoring -> Performance

Q) How to ANALYZE the GC.logs and define the parameters to for GC loging?
Ans-It’s always best to enable the Garbage collection Logging in our production environment as well because it does not cause any resource overhead or any side effect on weblogic server or an other application server’s performance.
GC log helps us in investigating man issues. Apart from issues it helps us to find out if some tuning is required based on the statistics of the Garbage collection. .

Garbage collection logging can be enable and collected in a separate log file by using the following JAVA_OPTIONS:
-Xloggc:D:/gcLogs/GCLogs.log
-XX:+PrintGCDetails
-XX:+PrintGCTimeStamps
As soon as you add these JAVA_OPTIONS which are JVM specific (above will work for Sun and Open JDKs fine) the JVM will start generating the garbage collection logging in the GCLog.log file.

You can notice something in the above output:

Point-1). [Full GC (System) [PSYoungGen: 38388K->0K(268800K)] It means a Full GC is happening on the complete Heap Area including all the Areas of the Java Heap Space.
Point-2). [GC [PSYoungGen: 230400K->19135K(268800K)] Indicates some small GCs which keep on happening in the young generation very frequently,This garbage collection cleans the Young Generation short living Objects. .
Point-3). Meaning of the [GC [PSYoungGen: 230400K->19135K(268800K)] line is around 256MB (268800K) is the Young Generation Size, Before Garbage Collection in young generation the heap utilization in Young Generation area was around 255MB (230400K) and after garbage collection it reduced up to 18MB (19135K) .
Point-4). Same thing we can see for Full Garbage collection as well….How effective the Garbage collection was…[Full GC (System) [PSYoungGen: 38388K->0K(268800K)]
[PSOldGen: 13545K->51794K(1789952K)] Here it says that around [(old)1789952K + young (268800K) ] memory space means OldGeneration is consuming 1.75GB space and
Young Generation is consuming around 255 MB space. So it means total Heap size is around 2GB.

----------------------------------------------------------------------------------------
Using GarbageCat tool for analysing the GC (garbagecat-1.0.0.jar ):
----------------------------------------------------------------------------------------
But analyzing the Garbage collection log like above technique Line by Line is very bad…so here we have an alternative was to analyze the Garbage Collection log in few
Seconds to see how much time the Full Garbage collection is taking as an average and other reports…etc.

Step1). Download the “garbagecat-1.0.0.jar (881 KB) ” tool from the follwing link:
http://garbagecat.eclipselabs.org.codespot.com/files/garbagecat-1.0.0.jar

Step2). Open a command prompt and then make sure that JAVA is set in the Path so that we can use “jar” utility of JDK to run the “garbagecat-1.0.0.jar” tool.

Step3). Put the “garbagecat-1.0.0.jar” file and the “GCLog.log” file in the same directory. then run the following command:
java -jar garbagecat-1.0.0.jar GCLog.log

Step4). As soon as ou run the above command you will see that in your current directory following files are created:
garbagecat-1.0.0.jar
GCLog.log
gcdb.lck
gcdb.log
gcdb.properties
report.txt

Step5). Now open the “report.txt” file to see the Over all report of the Garbage Collection something like following:
========================================
SUMMARY:
========================================
# GC Events: 12
GC Event Types: PARALLEL_SCAVENGE, PARALLEL_SERIAL_OLD
Max Heap Space: 2058752K
Max Heap Occupancy: 462018K
Max Perm Space: 39936K
Max Perm Occupancy: 19868K
Throughput: 95%
Max Pause: 306 ms
Total Pause: 1233 ms
First Timestamp: 4636 ms
Last Timestamp: 24449 ms
========================================
.
If you see that the Garbage Collection Max Pause time is very high like more than 5-7 Seconds then either we need to:
1.change thegarbage collection startegy or
2.need to tune the GC parameters and
3.JVM (Heap size, RAM Size, Swap Space, Pergen (if Sun JDK), TLA (if Jrockit) tuning needs to be done.

Q) Commonly know Erros related to GC?
Ans- out of memory :java heap space, out of memory:perm gen space, out of memory :unable to create native thread

Q) GC tuning parameters?
Ans- GC tuning is done through performance tuning parameters.

USE:-
http://middlewaremagic.com/weblogic/?p=4464
http://middlewaremagic.com/weblogic/?p=4500----JVM

HEAP DUMP AND ITS ANALYSIS USING Jmap AND Jhat RESPECTIVELY:
Here is a Simple Demonstration of using JMap to Generate the Binary heap Dump…Which we will analyze later using Jhat tool. These tools are very common and freely available for Download porpose. But from Sun JDK 1.6 Onwards it is by default available inside “<JAVA_HOME>\bin” directory.

What is Jmap And Why Not Jhat?
>Jmap is much better than Jhat utility because to start with Jmap utility u need not to apply any JAVA_OPTION on the WebLogic Server … you can directly start with any WebLogic Server which is Running on Sun JDK …. All u need to do is …Just find the Process ID of that WLS Server…thats all.

>Jmap generates the Heap Dump Much faster than Jhat.

>Jhat HeapDumps sometimes are seen as currupted file…But jmap is more reliable and generates the correct Heap Dump file. (correct heap dump generation percentage wise it is better than Jhat)

----------------------------------------------------------------
STEPS to generate Heap dump using Jmap in UNIX:
----------------------------------------------------------------
Step1). Start a Weblogic Server instance normally on your Local Machine and then find the Process ID (PID).

Step2). If you are using Unix Based Operating System then u can find out the Process ID (PID) by running the following Command:
ps -ef | grep java (or managed server name)

----------------------------------------------------------------------------------------------------
If you are using WINDOWS then follow the below Steps to find out the Process ID (PID):
----------------------------------------------------------------------------------------------------
a) Press “Ctrl+Alt+Del” 2 buttons together.
b) Press the “Task Manager” Button
c) Click on “Processes” Tab.
d) Now Select the Menu Item “View” — > “Select Columns”
e) Check the “PID (Process Identifier)” Check box as well…
f) Now u can see the Process Id of “java.exe” in the “Processes” Tab.

Step3).Start the “JMap” tool from “<JAVA_HOME>\bin” directory as following:
C:\bea103\jdk160_05\bin>jmap -dump:format=b,file=heapJMap.bin 7540

Note:
use: -J-d64 jvm option if your JVM is 64 Bit Jvm “jmap -J-d64 -heap pid”

Step4). To Read the Binary Heap Dump File … Jhat is one of the Best Tool… Please run the following command to inoke the “jhat” tool Http Server by passing the Heap
Dump File name…
C:\bea103\jdk160_05\bin>jhat -J-mx1024m heapJMap.bin

Step5).Now open a Web Browser with the following URL: “http://localhost:7000? - See more at: http://middlewaremagic.com/weblogic/?p=2241#sthash.fjv9RXSB.dpuf

Here the Jhat tool will display the following 3 info in histogram (i.e tabular type) format:
1.Name of classes (e.g: class char[], class.java.lang.String, class.java.util.HashMap, class.java.lang.Object[])
2.Class's instance count
3.Size of these instances
**instances= objects

JMAP options
-histo
Prints histogram on command line interface/putty
-finalizerinfo
Prints information on objects awaiting finalization.
-heap
Prints a heap summary. GC algorithm used, heap configuration and generation wise heap usage are printed.
-permstat
Prints class loader wise statistics of permanent generation of Java heap
- See more at: http://middlewaremagic.com/weblogic/?p=2241#sthash.fy9J6Ctd.dpuf

Use:
http://middlewaremagic.com/weblogic/?p=2241 (generating heap dump from jmap and analysing through jhat)
-----------------------------------------------------------------------
Heap dump generation and analysis through Jhat

Jhat tool comes free and available inside the “<JAVA_HOME>\bin” directory (from JDK1.6 onwards only). If you are using Jdk 1.5 or Lower version then u need to separately download the Jhat tool.from “https://hat.dev.java.net/”

Step1). Open the “startWebLogic.sh”(Unix Based OS) or “startWebLogic.cmd”(Windows OS) and then add the JAVA_OPTIONS
set SAVE_JAVA_OPTIONS=%JAVA_OPTIONS% --Xrunhprof:format=b,file=MyHeapDump.hprof

Step2). Now restart Your Server. As soon as you will start your Server you will find that “MyHeapDump.hprof” file is created inside your <DOMAIN_HOME> root directory:

Step3). Open the HeapDump using the Jhat tool like following:
C:\bea103\jdk160_05\bin>jhat -J-mx1024m C:\bea103\user_projects\domains\WS_Security_Domain\MyHeapDump.hprof
OR
place the file in some other location before opening it…
C:\bea103\jdk160_05\bin>jhat -J-mx1024m C:\myHeapDumps\MyHeapDump.hprof
Step4). As soon as u run the Obove command jhat tool starts a Http Server on default port 7000…Please open a browser with the following URL: http://localhost:7000 -

Step5). Object Query Language (OQL) OQL is SQL-like query language to query Java heap. OQL allows to filter/select information wanted from Java heap. While pre-defined queries such as “show all instances of class X” are already supported by JHAT

Browse: http://localhost:7000/oql/

USE:
http://middlewaremagic.com/weblogic/?p=2202 (generating and analysing heap dump from jhat)

All companies Interview questions

IBM

How to create weblogic domains using jython scripts and configuration wizard?
ssl certificate generation and installation?
how to generate selfsigned certificates and trusted certificates?
What is the difference b/w one way ssl and two way ssl certificates?
apache installation and integration with weblogic server?
where will you copy the modules into apache server?
What is auto deployement in weblogic?
How many types of deployment modes available in weblogic? What is the difference b/w staging and nostaging mode?
What is the difference between unicast and multicast messaging modes in cluster?
In unicast how does group leaders comunicate?
How do you achieve cluster session replication?
How to configure multipool in weblogic?
What is the deployment order? How to set the deployment order?
How to find out memory leaks?
How many types of garbage collection are there? What happens if major collection is not happening?
How do you enable garbage collection logs? Which command is used to generate garbage collection?
How to generate heap dump in weblogic? Explain the command?
Will the heap dump be generated automatically when we get an out of memory error? If yes, Which flag do you use to generate the heapdump automatically?
What is the difference between server hang and crash?
What is the difference b/w core dump and heap dump?
How to generate core dump?
How do you take thread dump in weblogic?
How to write a wlst script for deployment?
how to troubleshoot jdbc and jms issues?
Where the weblogic cache will be stored after the deployment?
How to configure foreign JMS servers?
What is jms bridge and why do we use it?
how to check list of available port numbers?
how to check running servers in linux?
What is the command to find out the operating system version?
How do you install patches in weblogic?
How to schedule the job in crontab? and what are the parametes do you use to set a job?
what is "at" command in unix?

NTTDATA Interview questions

1) Introduction to you self?
2)During deployment u can face memory issue how can u handle?
3)About garbage collection and its algorithems?
4)about session replication, types, configuration?
5)Entire about ssl, types, certificate genaration, an its configuration in admin console?
6) about Thread dump, how to take thread dump, how to analyze, how many types threads?
7)about heap dump?
8)about "Wily introscope " real time tool?
9) about shell scripting ?
10) top command?
11)about MQ, how many types of queues, trobleshooting of mq?
12)jms server, subdeployement, connection factory, trobleshooting of jms issues?
13)work manager, request classess, thread constrains, diff between thread constrains and Execute queue?

Mindtree Interview questions

Differences b/w different versions of weblogic server
Explain about your current environment
Difference b/w webserver and application server
Difference b/w developmode and production mode
jdk version for weblogic 11g
how to recover administrator password if boot.properties got currupted
stubs in cluster
http session replication
t3 protocal
msi mode in weblogic
apache installation
how to enable modules
virtual hosting in apache
what is the difference b/w jndi and jdbc
how to do connection pool shrink
what is the differenc b/w server crash and hang
how many log levels available
what is the difference b/w execute Queues and work managers
how to find out the memory leaks in the application
how to take thread dump and heap dump and explain the jmap command
how to find ip address?
how to find port numbers?
find command
top command
touch command
how to trouble shoot wlst python script issues
how to set deployment order
how dns resolve the client request
vmstat
swap
iostat

TCS Interview questions

1)what is persistent store?
2)difference b/w weblogic 8 & 10?
3)difference b/w Queue and Topic?
4)what is permSize?
5)how to increase the heap size?
6)what is subdeployement ? use of subdeployement?
7)how to deploy an application using wlst script?
8)type of deployement mode?
9)how to clear the weblogic cache?
10)how to check the memory & CPU usage?
11)how to check the disk usage?

CSC Interview questions

1) What is weblogic domain?
2) What are the basic requirements for cluster?
3) What are the benifits/advantages of clustering?
3) How does cluster work?
4) Explain cluster algorithms
5) What is the session replication? How does it work when the failover situation?
6) What is primary and secondary replication groups?
7) What is persistance store? How many types of persistance mechanisms are there?
8) HOw can we achive load balancing for cluster?
9) What is the diff b/w data source and multidata source?
10) What are the diff types of multidata source algorithms available? and explain?
11) HOw does apache know whether the weblogic server is failed state in cluster?
12) HOw to handle stuck thread issues in weblogic?
13) HOw to handle memory issue in weblogic?
14) Explain the steps for creating jms setup?
15) Why dont we target jms server to cluster? and why we target data source to cluster?
16) what is subdeployment in weblogic?
17) What is the diff b/w queue and topic?
18) what is the diff b/w queue and distributed queue?
19) How to configure external security LDAP?
20) HOw to configure siteminder ? What is SSO (single sign on )?

TechMahendra Interview questions

1.roles and responsibilities
2.how to ceate domain
3.jms configurations
4.what is connection factory
5.what is jms module
6.jvm out of memory issues
7.what is garbage collector
8.how to configure datasorce
9. work manager
10.wlst
11.ticketing tool
12.msi mode

HCL Interview questions

First Round ( Technical )
1) How do you create weblogic domain
2) What is the purpose of node manager
3) How do you create cluster? Pre-requisites for cluster creation?
4) What is the process for connecting to the data base from the application?
5) What is JNDI?
6) How to test the connection pool from console?
7) What should be running from the DB side to connect to the data base?
8) What is the differences b/w unicast and multi cast?
9) Do you have exp in performance tunning? How do you handle stuck thread issues?
10) What are the different thread states?
11) Explain how to handle memory issue? What are the types of memory leaks?
12) How do you check all the running java processes in unix?
13) How do you check updated log file?
14) What is ulimit command in unix?
15) Steps for creating data source and connection pool from the console?
16) How to trouble shoot the deployment issues?
17) Application deployed it in weblogic and weblogic is down, The requesting is comming from apache and apache is running.
Will you be able to access the static content when weblogic is down?
13.deployment modes? stagemode, nostage, external stage
14.top command - complete analysis of top
15.df - kh
16.find ( how to find the files which are older then 5 days) use -mtime. search for the syntax in google
17.weblogic life cycle
18.log levels
19.weblogic domain structure
20.config file location
21.node manager - how to add the new domain into node manger by editing property files
22.solaris - commands
23.parameters of jvm
24.diff between java heap and perm? and JVM arguments
26.garbage collection algorithms
27.scenarios
28. How to handle stuck thread issues?

NESS Technologies Interview questions

1) Introduce your-self with current Environment and Work Experience?
2)can you tel me recently faced issues?
3)MQ
What is transmission queue?
Remote Queue?
4) currently which version of weblogic using and what are the features ?
5) what is thread dump and how to analyze, you find blocked threads what can u do?
6)application running in weblogic suddenly it will slow what are the possible reasons?
7)what is heap dump, how can you take, and its syntax?
8)what is garbage collection?
9) what is hacking threads in weblogic?
10)how to install apache?
11)what is virtual hosting?
12) what is "keep alive" in ( apache)?
13)what is harizontal clustering, how it works?
14)ssl how will provide security for our application? how to genarate keys tel me everthing process ?
15)how to create datasource?
16)what is "multidatasource"?
17) database connection leak issues, in weblogic? if every thing is fine database side fine, network is fine what is the reason?
18)diff between XA-driver and Non-xA driver?
19)How to release connection from connectionpool?
20)If Jms issues occured, how to troble?
21)find command
22)Tcp, netstat -anp(what is "a"), ps -ef, awk, cut, what is diff between awk and cut?
23)vi editor
how to open 10 files at a time in vi editor
24) what is "nodemanager", nodemanager process, port numbrt of node manager?
25)telnet
26)pack, unpack?
27)scp
28)how to create softlink, hard link files in linux?
29)what is the process connecting to the database, if weblogic is not connecting to the database what could be the reason?
30)native momory issues?

WIPRO Technologies Interview questions

DIFF B/w Jdk 1.5 and 1.6 ?
DIFF B/w apache 2.0 and 2.2 ?
DIFF B/w wls 8 and wls 9 ?
wls installation in gui mode ?
Data source and conection properties ?
how to create Data source ?
patch installation ?
deployment modes ? diff b/w stage and no stage mode ?
cpu utilizaton ?
war , ear , jar files ?
what deployment descriptor ?
what is thread?
Log levels ?
Domain creation ?
Deployments ?

Wels Fergo Telephonic Interview Questions

1.Tell me about yourself and roles and responsibilities in current Project?
2.How to install the servers and configure the domains? Do you use any tools or scripts?
3.Do you have any experience in writing scripts?
4.If there is any issue with script while running, then how do you debbug the script?
5.If i will give a generic jar to install 32-bit of weblogic server, How do you do that?
6.Is JMS server targetting to Cluster?
7.What is the use of having Subdeployments?
8.How can MQ get the message from Weblogic Server?
9.Can you tell the functionality of SSL? How does it work ?
10.What is a domain wise administration port? Do you have any idea?
11. What are the webservers you know? What version of apache you are using?
12.What is the weblogic version you are using?
13.How to display only files using ls command?
14.How can you debbug a shell script?
15.How to print the word hello from a test file?
16.How to remove empty lines from a file?
17.How to print the lines using sed command?

interview

what are the web servers and app servers?

What is an example of a Web server?

why web servers are used ?

is tomcat web server ?

What does a web server do?

How do I download a Web server?

What is the difference between Apache and Tomcat?

What is server?

Is server a computer program ?

What are the features of Web server?

What is Apache Tomcat Server tutorial?

What is difference between Jboss and Tomcat?

How do I find my server address?

How do I make my PC into a server?

What are the types of servers?

Is Apache a Web server?

What is the difference between Apache and Tomcat?

Q.What are safeguards for modifying the config.xml file?

How do I edit the config.xml file?

Weblogic

What Is Weblogic?

WebLogic interview

All companies Interview questions

IBM

NTTDATA Interview questions

Mindtree Interview questions

TCS Interview questions

CSC Interview questions

TechMahendra Interview questions

HCL Interview questions

NESS Technologies Interview questions

WIPRO Technologies Interview questions

Wels Fergo Telephonic Interview Questions

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