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NJIT

Apache Tomcat(Version 6.0)

Presented by

Venkat pinagadi

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Apache is the most common HTTP Web Server on the Internet. It is the Web server used at http://web.njit.edu

The Tomcat server is a Java-based Web Application container which is used to run Servlet and Java Server Pages (JSP) Web applications.

Tomcat has become the reference implementation for both the Java Servlets and Java Server Pages specifications.

Tomcat was chosen to be the official Sun Web Component (JSP/Servlet ) Container Reference Implementation.

What is Apache Tomcat?

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What is Apache Tomcat? [Contd.]

Apache Tomcat is used to serve Java Servlets and Java Server Pages. It's a complex piece of software and though the documentation is very comprehensive, it helps to have a good reference work to hand.

It is an open source Java Servlet application server used to deploy Java applications after they are built with JSP and Servlets. It can be used as a stand-alone product or it can be integrated with the Apache server.

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What is a container?

Containers are the interface between a component and the low-level platform-specific functionality that supports the component.

Before a Web, enterprise bean, or application client component can be executed, it must be assembled into

a J2EE module and deployed into its container.

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J2EE Containers (Server)

J2EE server : The runtime portion of a J2EE product. A J2EE server

provides EJB and Web containers. Enterprise JavaBeans (EJB) container : Manages the execution of enterprise beans for J2EE

applications. Enterprise beans and their container run on the J2EE server.

Web container : Manages the execution of JSP page and servlet

components for J2EE applications. Web components and their container run on the J2EE server.

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J2EE Containers (Client) Application client container : Manages the execution of application client components.

Application clients and their container run on the client. Applet container : Manages the execution of applets. Consists of a Web

browser and Java Plug-in running on the client together.

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J2EE Server and Containers

Tomcat

JBoss,WebSphere,WebLogic, etc

Browser

ApplicationClient

ClientContainer

Client Machine

Java Web Container

EJB Container

Servlet JSP page

EntityBean

SessionBean

Database

Client Web Server (Apache)

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Working environments

Java is already installed on PCs in the NJIT PC labs and the Solaris and Linux labs on the second floor of GITC. Tomcat is also installed on the Solaris machines. It is recommended that all work with Tomcat be done on AFS31 through AFS35.

The installation guides on the following slides are for your own computers.

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Initial Setup

The Java Software Development Kit (JDK) is aimed at Java developers. It consists of Sun's Java Runtime Environment bundled with programming tools. Java Runtime Environment (JRE) is the software required to run any application deployed on Java platform.

Download J2SE Runtime Environment Install the JRE according to the instructions included

with the release.

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Installation of Apache Tomcat

Initiate the download of Tomcat from the site

http://tomcat.apache.org/ View the corresponding documentation

and setup for help in running on various platform and requirements.

After downloading follow the instructions to start installation.

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Start Up Tomcat

Tomcat can be started by executing the following commands:

$CATALINA_HOME\bin\startup.bat (Windows) $CATALINA_HOME/bin/startup.sh (Unix) After startup, the default web applications included with

Tomcat will be available by visiting: http://localhost:8080/

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Link Details

Path to file protocol is http

Can OMIT if usingROOT as defaultServer is local

Listens on port 8080

http://localhost:8080/myapp/chapter01/sample00.html

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Shut Down Tomcat

Tomcat can be shut down by executing the following command:

$CATALINA_HOME\bin\shutdown (Windows)

$CATALINA_HOME/bin/shutdown.sh (Unix)

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Enabling SSI and CGI support

SSI and CGI are disabled by default for security reasons to enable them:

To enable and configure CGI support, please see the cgi-howto.html page.

To enable and configue SSI support, please see the ssi-howto.html page.

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Security Managers URL

In order to grant security permissions to JARs located inside the web application repository, use URLs of of the following format in your policy file:

file:${catalina.home}/webapps/examples/WEB-INF/lib/driver.jar

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Enabling invoker servlet:(NJIT is non-standard)

Starting with Tomcat 4.1.12, the invoker servlet is no longer available by default in all webapps. Enabling it for all webapps is possible by editing $CATALINA_HOME/conf/web.xml to uncomment the "/servlet/*" servlet-mapping definition.

Using the invoker servlet in a production environment is not recommended and is unsupported. More details are available on the Tomcat FAQ at

http://tomcat.apache.org/faq/misc.html#invoker. WARNING! On NJIT Systems, the invoker “servlet” is in use, and

needs to be maintained if you edit your web.xml. A URL must be in the form http://web.njit.edu/~<ucid>/servlet/<classname> for the servlet to be found and executed by Tomcat.

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UCS at NJIT

Apache Tomcat is installed on UCS and servlets can be run after configuration of your account.

Basic information will be available from link: http://web.njit.edu/all_topics/Servers/Tomcat/ Changes to servlets are seen immediately. The

first time you set up Tomcat, servlets are visible only after the NJIT server is restarted which is done once a day at 6:00 AM.

As of 03/2008 Apache is running on afs31-afs35.

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Any other web server using port 8080

This happens usually when any other web server (or any process) has laid claim to port 8080 and this one is the default HTTP port that Tomcat attempts to bind to at startup. So for changing this, open the file:

$CATALINA_HOME/conf/server.xml and search for '8080'. Change it to a port that isn't in use,

and is greater than 1024, as ports less than or equal 1024 require superuser (root) access to bind under UNIX. Restart Tomcat. Be sure that you replace the "8080“ in the URL you're using to access Tomcat. If you change the port to 1977, you would request the URL http://localhost:1977/ in your browser.

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Out of environment space error

An "out of environment space" error

This happens when running the batch files in Windows 95, 98, or ME operating systems. Right-click on the STARTUP.BAT and SHUTDOWN.BAT files. Click on "Properties", then on the "Memory" tab. For the "Initial environment" field, enter in something like 4096. After you click apply, Windows will create shortcuts which you can use to start and stop the container.

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The 'localhost' machine isn't found error

The 'localhost' machine isn't found.

This could happen if you're behind a proxy. If that's the case, make sure the proxy configuration for your browser knows that you shouldn't be going through the proxy to access the "localhost". In Netscape, this is under Edit/Preferences -> Advanced/Proxies, and in Internet Explorer, Tools -> Internet Options -> Connections -> LAN Settings.

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Apache Tomcat Updates

The latest version of Apache Tomcat changes regularly so keep updated by visiting the link :

http://tomcat.apache.org/

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Advantages of Tomcat

1) It is an open source application server 2) It is a light weight server (no EJB) 3) It is easily configured with apache and IIS 4) Very stable on Unix systems 5) Good documentation online 6) Java Sun compliant 7) Does not require a lot of memory at startup 8) It is free, yet high quality!

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References:

http://tomcat.apache.orghttp://java.sun.comhttp://jakarta.apache.org/