Apache Tomcat Interview Questions

Apache Tomcat is also referred to Tomcat Server which is developed by the Apache Software Foundation (ASF). It is an open-source Java Servlet Container. Tomcat executes various Java EE specs comprises of JavaServer Pages (JSP), Java Servlet, WebSocket and Java EL and gives you a "pure Java". It provides you with an efficient HTTP web server environment in which Java code can operate.

Tomcat is managed and maintained by open community developers under the aegis of Apache Software Foundation.

Tomcat is a basically a web server and a java servlet container from Apache Foundation. It can be used solitary as well as with the web servers. Most of its recent versions are static content with the speed same as http. It uses the request message exchange pattern to solve the web servers and pages.

It is a component of a web server that is interacting with Java servlets. It is also held responsible for the management life cycles of servlets, mapping a URL for a particular servlet and assuring that the request has always the genuine access. Servlet containers also handle the request from servlets, Java server pages files and many other including the server side code.

Once Jasper has done the compilation it converts JSP into the servlet and allows Catalina to handle it further. Catalina is a Tomcat's servlet container. It also implements all of the specifications for Java server pages and servlets. Catalina is a Java engine that is built into Tomcat providing an environment for the servlets to run efficiently.

In order to manage the large applications Tomcat cluster is used. It is used more efficiently for load balancing and for managing most of the traffic, Apache Tomcat cluster is utilized. For the Tomcat server, it can provide multiple instances based on its content.

It is a feature which is added in Tomcat in order to facilitator schedules of system upgrades without actually affecting the live environment. By dispatching the live traffic request from the main server to a temporary server on an entirely different port this is done. It is terminated until the main server is upgraded on the main port. It is a very beneficial feature to deal with the request on a high traffic web application.

Tomcat initially started as a servlet reference which was implemented by James Duncan Davidson. He was known as a software architect at Sun Microsystems Group. He was the person who started helping to make the open source project and work as a fusion for Sun Microsystems and Apache Software Foundation. The most tragic part of Tomcat with the development of this and another Apache was that a software automation tool also got developed as a side effect.

The Apache Software Foundation is an organization that looked after most of the open source projects. Jakarta is the name of the Java-based project on this foundation and Tomcat is a web server which is handling server data off Java. Tomcat is basically a part of the Apache Jakarta project and a reference for the implementation of servlet and JSP standards.

The default port allocated for Tomcat is 8080. Well, it can be changed by editing the file under the conf folder name in the Tomcat install directory server.xml. By changing the property to the desired port connector port =”8080” and then restart the Tomcat so that it can save changes can be implemented.

Tomcat can use SSL but for that, you need to make some configuration. You have to do the following tasks-

• Generate a keystore
• Then add a connector in server.xml
• Restart Tomcat

The server.xml file is the main Tomcat configuration file which is responsible for specifying the entire setup and Tomcat configuration while startup.

This file is derived from the servlet specification in Tomcat. It contains information which is used to deploy the components on web applications or servers.

Under the Tomcat-users.XML configuration files, the entire Tomcat users are specified and defined. It is located in the conf folder in the server root of Tomcat.

The connectors in the Apache project are a part of the project itself providing web server plug-in for the connection of web service with Tomcat and all the other back-ends. The consequent supported Web Servers are-

• Apache http server with a plug-in named mod_jk.
• Microsoft IIS with a plug-in named ISAPI redirector.
• iplanet web server with a plug-in named NSAPI redirector.

The name of the Tomcat JSP engine is Jasper. It passes the JSP files for the compilation of them into Java code as servlets. With the running time, it detects all of the changes in JSP files and recompiles them often. Jasper is also the Java server pages Handler and internally it deals with the necessary compiling.

A connected component for the Tomcat's project is Coyote, which supports the HTTP 1.1 protocol as a web server. It allows Catalina to act as a basic web server by serving the local files as HTTP documents. It also deals with the incoming connections for a server with the specific TCP port and forwards the request messages to the Tomcat engine. Once a response is received it forwards it back to the client.

The host is an element in Tomcat. It is an association in a network name for the server. Context, on the other hand, is an element which represents a web application, running with a particular virtual host. Web applications are based on the Web Application Archive (WAR) file or correlating directory which is having all the unpacked contents specified with the servlet description.