Apache Tomcat Administration

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

Apache Tomcat Administration Interview Questions

1) What is Apache Tomcat? 

Apache Tomcat is basically a Web Server and Servlet system which is an open-source (i.e. freely available on the internet) and is created by Apache Software Foundation. It is the server mostly used by Java Developers.

The server is nothing but a computer program that provides service to other computers.

There are basically two types of server:

1.      Application Server

2.      Web Server

Apache Tomcat offers HTTP protocol, which means the user can connect with the server from anywhere by the URL provided and can access the Java application.
 

2) Why do we require Apache Tomcat? 

It is required to run Java Web Applications on the host and server-based systems. It also helps to run JSP and Servlets.
 

3) What is the default port for Apache Tomcat? 

The default port of Apache Tomcat is port 8080.
 

4) What is the name of inbuilt Web Container in Tomcat? 

The name of the inbuilt Web Container in Tomcat is Catalina which is present in the bin directory.

Catalina is used for loading all the requests related to HTTP and can instantiate the objects of GET () and POST () methods.
 

5) What are the types of batch file with the help of which we can Start and Stop Apache Tomcat Server? 

There are basically two types of batch files with which we can Start and Stop the Server.

They are as follows:

1.      Startup.bat

2.      Shutdown.bat

 
6) How can we configure Apache Tomcat in Java Eclipse IDE or explain the setup of Apache Tomcat Server? 

It is really very easy and simple to install Apache Tomcat in Eclipse.

The steps are mentioned below:

1.      Select the Server’s tab at the bottom side of IDE.

2.      Right-click on blank space or white space.

3.      Click on New

4.      Click on Servers

5.      Choose Tomcat and its next version.

6.      Click on next

7.      Select the browse button

8.      Select the Tomcat root folder

9.      Click next

10. Click Add all

11. Click Finish

12. Validate the blank area Tomcat must be displaying.

 
7) How do you Start and Stop Apache Tomcat using services? 

The services are as follows:

• Services httpd start
• Httpd stop

 
8) Which is the vital configuration file that is used in Apache Tomcat? 

The vital configuration file that is used in Apache Tomcat is httpd.conf
 

9) How do you find which version of Apache Tomcat web server is running? 

The best way to find the currently running version is stated below:

1.      Sign in to the web-server

2.      Go to apache instance and bin folder

3.      Run “httpd -v” command to get version detail.

 
10) Explain the types of connectors used by Apache Tomcat. 

Apache Tomcat basically uses two types of connectors which are as follows:

1.      HTTP Connectors: HTTP connectors possess attributes which can be modified to determine exactly how it works and access functions such as redirects and proxy forwarding.

2.      AJP Connectors: AJP connectors follow the AJP protocol in place the of HTTP but work just same as HTTP connectors. They are implemented in Apache Tomcat through the plug-in technology mod_jk.

 
11) How Do I Can Change The Default Home Page Loaded By Tomcat?

We can easily override home page via adding welcome-file-list in application $TOMCAT_HOME/webapps//WEB-INF /web.xml file or by editing in container $TOMCAT_HOME/conf/web.xml

In $TOMCAT_HOME/conf/web.xml, it may look like this: 

    index.html

    index.htm

    index.jsp 

Request URI refers to a directory, the default servlet looks for a "welcome file" within that directory in following order: index.html, index.htm and index.jsp
 

12) How To We Can Change Tomcat Default Port? 

8080 is the default HTTP port that Tomcat attempts to bind to at startup.  To change this, we need to change port in $ TOMCAT_HOME /conf/server.xml, in that we can search 8080 and after getting below statement

We can change 8080 to other port like 8081, we need to restart tomcat to take effect. We required changes in URL as http://localhost:8081/.
 

13) What Is Default Session Time Out In Tomcat? 

The default session timeout 30 minutes in tomcat and can change in $TOMCAT_HOME/conf/web.xml via modify below entry

        30

 
14) Explain Directory Structure Of Tomcat? 

Directory structure of Tomcat are:

bin - contain startup, shutdown, and other scripts (*.sh for UNIX and *.bat for Windows systems) and some jar files also there.

conf - Server configuration files (including server.xml) and related DTDs. The most important file in here is server.xml. It is the main configuration file for the container.

lib - contains JARs those are used by container and Servlet and JSP application programming interfaces (APIs).

logs - Log and output files.

webapps – deployed web applications reside in it .

work - Temporary working directories for web applications and mostly used during in JSP compilation where JSP is converted to a Java servlet.

temp - Directory used by the JVM for temporary files .

 
15) How Do You Create Multiple Virtual Hosts? 

If you want tomcat to accept requests for different hosts e.g. www.myhostname.com then you must

• Create ${catalina.home}/www/appBase , ${catalina.home}/www/deploy, and ${catalina.home}/conf/Catalina/www.myhostname.com
• Add a host entry in the server.xml file
• Create the the following file under conf/Catalina/www.myhostname.com/ROOT.xml
• Add any parameters specific to this hosts webapp to this context file
• Put your war file in ${catalina.home}/www/deploy
• When tomcat starts, it finds the host entry, then looks for any context files and will start any apps with a context.

 
16) Explain How Running Tomcat As A Windows Service Provides Benefits? 

Running Tomcat as a windows service provides benefits like:

• Automatic startup: It is crucial for environment where you may want to remotely re-start a system after maintenance
• Server startup without active user login: Tomcat is run oftenly on blade servers that may not even have an active monitor attached to them. Windows services can be started without an active user
• Security: Tomcat under window service enables you to run it under a special system account, which is protected from the rest of the user accounts 

17) Suppose When We Are Starting Startup.bat File Of Tomcat Server It Is Not Started. Dos Window Appears For A Second Only. What We Need Do? 

Your set up might have been not done well.

Make sure you have added tomcat root directory path in the CATALINA_HOME environment variable and added the bin path in the path variable.
 

18) Explain The Concepts Of Tomcat Servlet Container? 

• Tomcat Servlet Container is a servlet container. The servlets runs in servlet container.
• The implementation of Java Servlet and the Java Server Pages is performed by this container.
• Provides HTTP web server environment in order to run Java code.
• Reduces garbage collection
• Native Windows and Unix wrappers for platform integration

 
19) Mention What Is The Output Of Select * From Tab? 

It displays the default tables in the database
 

20) Can I Set Java System Properties Differently For Each Webapp? 

No. If you can edit Tomcat's startup scripts, you can add "-D" options to Java. But there is no way to add such properties in web.xml or the webapp's context.
 

21) Explain How Servlet Life Cycles? 

The life-cycle of a typical servlet running on Tomcat:

• Tom-cat receives a request from a client through one of its connectors
• For processing, this request Tomcat maps this request to appropriate
• Once the request has been directed to the appropriate servlet, Tomcat verifies that servlet class has been loaded. If it is not than Tomcat wraps the servlet into Java Bytecode, that is executable by the JVM and forms an instance of the servlet
• Tomcat initiates the servlet by calling its init The servlet contains code that is able to screen Tomcat configuration files and act accordingly, as well as declare any resources it might require
• Once the servlet has been started, Tomcat can call the servlet’s service method to proceed the request
• Tomcat and the servlet can co-ordinate or communicate through the use of listener classes during the servlet’s lifecycle, which tracks the servlet for a variety of state changes.
• To remove the servlet, Tomcat calls the servlets destroy method.

 
22) How Web Server Handles Multiple Requests For Same Action Class(struts) Concurrently? 

Struts or any webserver makes new thread for each new request. so multiple request is served with new request object.

 
23) Explain When You Can Use . And When You Can Use []? 

If you are running a bean property, use the .operator, and if you are executing a map value or an array index, it is preferred to use the [] operator. Although you can use these operators interchangeably.

 
24) What Is Webservers? Why It Is Used? 

Transaction with HTTP request and HTTP response is called webserver.

Using the internet listening the HTTP request and providing the HTTP response is also called webserver.It gives only html output.It will not process business logic .They can provide Http server.They are static.

 
25) Explain What Is Tomcat Coyote? 

Tom coyote is an HTTP connector based on HTTP/ 1.1 specification which receives and transport web requests to the Tomcat engine by listening to a TCP/IP port and sent request back to the requesting client.

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