Tomcat server

Apache TomcatApache Tomcat
Representation and Management of
Data on the Web

What is Tomcat?What is Tomcat?
• Tomcat is a Servlet container (Web server that interacts
with Servlets) developed under the Jakarta Project of
Apache Software Foundation
• Tomcat implements the Servlet and the Java Server
Pages (JSP) specifications of Sun Microsystems
• Tomcat is an open-source, non commercial project
- Licensed under the Apache Software License
• Tomcat is written in Java (OS independent)

A Servlet ExampleA Servlet Example
public class HelloWorld extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
PrintWriter out = response.getWriter();
out.println("<html><head><title>Hello</title></head>");
out.println("<body>");
out.println("<h2>" + new java.util.Date() + "</h2>");
out.println("<h1>Hello World</h1></body></html>");
}
} HelloWorld.java
http://localhost/dbi/hello

A JSP ExampleA JSP Example
<html>
<head>
<title>Hello World</title>
</head>
<body>
<h2><%= new java.util.Date() %></h2>
<h1>Hello World</h1>
</body>
</html> hello.jsp
http://localhost/dbi/hello.jsp

Another JSP ExampleAnother JSP Example
<html>
<head><title>Numbers</title></head>
<body>
<h1>The numbers 1 to 10:</h1>
<ul>
<% int i;
for (i=1; i<=10; ++i) { %>
<li>Number <%=i%> </li>
<%}%>
</ul>
</body>
</html> numbers.jsp
http://localhost/dbi/numbers.jsp

Tomcat Directory StructureTomcat Directory Structure

Base and Home DirectoriesBase and Home Directories
• The directory TOMCAT-HOME contains
executables and libraries required for the server
launching, running and stopping
- This directory is placed under /usr/local/…
• The directory TOMCAT-BASE contains the
Web-site content, Web applications and
configuration data
- This directory is placed under your home directory

Installing TomcatInstalling Tomcat
• Create a directory for tomcat base
- For example: mkdir ~/tomcat-base
• Set the environment variable CATALINA_BASE to
your tomcat-base directory
- For example: setenv CATALINA_BASE ~/tomcat-base
- Insert this line into your .cshrc file
• Run ~dbi/tomcat/bin/setup
• $CATALINA_BASE is now a regular Tomcat base
directory, and Tomcat is ready to run

Running TomcatRunning Tomcat
• To start tomcat use ~dbi/tomcat/bin/catalina run
• Or, in background, ~dbi/tomcat/bin/catalina start
• To stop tomcat use ~dbi/tomcat/bin/catalina stop
• To see the default page of Tomcat from your browser
use the URL http://<machine-name>:<port>/
- machine-name is the name of the machine on which Tomcat
runs and port is the port you chose for Tomcat
• You can also use http://localhost:<port>/ if your
browser runs on the same machine as Tomcat

From Scratch to ServerFrom Scratch to Server

Choosing a port for TomcatChoosing a port for Tomcat
• In the file $CATALINA_HOME/conf/server.xml you
will find the element Connector of Service “Catalina”
• Choose a port (greater than 1024) and change the value
of the port attribute to your chosen one:
<Server>
…
<Service name="Catalina”>
<Connector port="8090"/>
…
</Service>
…
</Server>

Creating Web ApplicationsCreating Web Applications

Creating Web ApplicationsCreating Web Applications
• A Web application is a self-contained subtree of
the Web site
• A Web application usually contains several Web
resources like HTML files, Servlets, JSP files,
and other resources like Database tables
• Each Web application has its own subdirectory
under the directory
$CATALINA_BASE/webapps/

The Directory Structure of a WebThe Directory Structure of a Web
ApplicationApplication
• Tomcat automatically identifies a directory
$CATALINA_BASE/webapps/myApp/ with
the relative URL /myApp/
• For example, a file named index.html in myApp
is mapped to by the following URLs:
http://machine:port/myApp/index.html
http://machine:port/myApp/

• You can also use subdirectories under myApp
• For example: the file myApp/myImages/im.gif
is mapped to by the URL
http://machine:port/myApp/myImages/im.gif
• By default, Tomcat maps the root directory
(http://localhost:8090/) to the directory
webapps/ROOT/
- You can change this default

• An application's directory must contain the
following:
- The directory WEB-INF/
- A legal web.xml file under WEB-INF/
<web-app>
</web-app>

From Scratch to ApplicationsFrom Scratch to Applications

Configuring a Web ApplicationConfiguring a Web Application
• Application-specific configuration and declarations are
written in the file myApp/WEB-INF/web.xml
• This file contains:
- Servlet declarations, mappings and parameters
- Default files for directory requests
- Error pages (sent in cases of HTTP errors)
- Security constraints
- Session time-out specification
- Context (application) parameters
- And more…

Error PagesError Pages
• Use the error-page element to define the page
sent in case of an HTTP error that occurs within
the application context
• An error page element has two sub elements:
- error-code - the HTTP error status code
- location - the page that should be sent

Welcome Page ExampleWelcome Page Example
<html>
<head><title>Not Found</title></head>
<body>
<h1 style="text-align:center; color:green">
Sorry, no such file...
</h1>
</body>
</html>
my404.html
<web-app>
<error-page>
<error-code>404</error-code>
<location>/my404.html</location>
</error-page>
</web-app>
web.xml

Welcome PagesWelcome Pages
• The (optional) welcome-file-list element contains a list
of file names
• When the URL request is a directory name, Tomcat
automatically brings the first file on the list
• If that file is not found, the server then tries the next file
in the list, and so on
• This file can be of any type, e.g., HTML, JSP, image,
etc.
• The default welcome list for all applications is set in
$CATALINA_BASE/conf/web.xml

Welcome Page ExampleWelcome Page Example
<html>
<head><title>Welcome</title></head>
<body>
<h1 style="text-align:center; color:red">
Welcome Dear Visitor!
</h1>
</body>
</html>
welcome.html
<web-app>
<welcome-file-list>
<welcome-file>welcome.html</welcome-file>
<welcome-file>index.html</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
web.xml

Tomcat and Java ClassesTomcat and Java Classes
• Tomcat uses Java classes you provide in order to
run Servlets and JSP files
- For example, the Servlets themselves!
• Tomcat 5.x initialization scripts ignore your
environment CLASSPATH variable
• Classes are expected to be placed (or linked) at
some predefined places in its directories

Java Class LocationsJava Class Locations
• Tomcat expects to find Java classes in class files (in a
directory named classes) and JAR files (in a directory
named lib) in the following places:
• TOMCAT-HOME/common/
- Basic runtime classes. No need to touch this directory
• $CATALINA_BASE/shared/
- Classes that are used by all the Web applications
• $CATALINA_BASE/webapps/myApp/WEB-INF/
- Application-specific classes (Servlets are typically here)

Java Class LocationsJava Class Locations

Classes Provided by DBIClasses Provided by DBI
In order to provide the classes you need, like
ORACLE, SAX and DOM-related packages, the
Tomcat-setup script links the directory
$CATALINA_BASE/shared/lib/ to
~dbi/tomcat/shared/lib/, thus the latter
packages are automatically known by your
Tomcat server

Tomcat 5.0 ManagerTomcat 5.0 Manager
• Tomcat 5.0 comes with a Web application called
“manager”, which supports functions for
managing Web applications
• You can either use the HTML interface at
http://<machine>:<port>/manager/html/ or send
direct HTTP requests to it
• You will need to authenticate as a privileged user
- Use the username “admin” with no password

Tomcat 5.0 ManagerTomcat 5.0 Manager
• Using the manager, you can
- Deploy a Web application by posting a WAR file
- Undeploy a deployed Web application
- Start/stop a Web application (make it available/unavailable)
- Reload an existing Web application (unpack new WARs)
• Warning: while “stop” makes an application unavailable,
“undeploy” deletes the application directory and WAR file
from webapps/

Tomcat and EclipseTomcat and Eclipse
• You can use an Eclipse plugin for Tomcat Web-
application development
• The “Sysdeo Eclipse Tomcat Launcher” plugin
is installed in CS
• Using this plugin, you can start/stop the server,
reload an application, etc.
• Detailed explanations in the course home-page

Tomcat server

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