A348/A548 Mastering the World-Wide Web (4/3 cr.)

Spring Semester 2003

Lab Notes Ten: Java Applets. Installing Tomcat.

Quick summary of some important notes:

the needed file is called jakarta-tomcat-4.0.4.tar.gz and gunzip is needed
the ports have been listed on the students since the beginning of the semester
sample configuration file is in the notes below
make sure you use gnu's tar (revisit your installation of PHP to see what's needed)
archive is in /l/www/classes/a348/software (as expected, I hope)
sample links will be activated within the next few (6) days (if you know what I mean)

And now the lab notes.

We first "create" an applet, and install it on our website.

1. Create the source code of the applet.

For the purpose of this lab you will get the source code from me. We will install a fairly complex applet, and we will ignore the source code for now.
Take the following files
/u/dgerman/fall2000/lab7/Matrix3D.java
/u/dgerman/fall2000/lab7/XYZApp.java
from my home directory and put them in a special directory (called lab10) under your document root directory of your web server. Once you copy them you have the source code; that makes it as if you have written the source code yourself.

Here's how you do that:

burrowww.cs.indiana.edu% pwd
/nfs/paca/home/user1/dgerman/apache/apache_1.3.22/htdocs/lab10
burrowww.cs.indiana.edu% cp /u/dgerman/fall2000/lab7/Matrix3D.java .
burrowww.cs.indiana.edu% cp /u/dgerman/fall2000/lab7/XYZApp.java . 
burrowww.cs.indiana.edu% ls -l
total 20
-rw-r--r--   1 dgerman  faculty     6327 Oct 11 09:32 Matrix3D.java
-rw-r--r--   1 dgerman  faculty    13161 Oct 11 09:32 XYZApp.java

Please don't overlook the dots (.) at the end of the commands. Thank you.

2. Compile them (prepare the bytecode).

Use javac to compile the source code. This will create a number of .class files that may or may not be in one-to-one correspondence with the source code (java) files. The number and names of the .class files can be deduced from the actual contents of the source code files. Of those created XYZApp.class is the main file (although for applets we don't have a main method) and we need to make a note of that.

Here's how you do that:

burrowww.cs.indiana.edu% pwd
/nfs/paca/home/user1/dgerman/apache/apache_1.3.22/htdocs/lab10
burrowww.cs.indiana.edu% ls -l
total 20
-rw-r--r--   1 dgerman  faculty     6327 Oct 11 09:34 Matrix3D.java
-rw-r--r--   1 dgerman  faculty    13161 Oct 11 09:34 XYZApp.java
burrowww.cs.indiana.edu% javac *.java
Note: XYZApp.java uses or overrides a deprecated API.  Recompile with "-deprecation" for details.
1 warning
burrowww.cs.indiana.edu% ls -l
total 35
-rw-r--r--   1 dgerman  faculty     2003 Oct 11 09:35 Atom.class
-rw-r--r--   1 dgerman  faculty     3683 Oct 11 09:35 Matrix3D.class
-rw-r--r--   1 dgerman  faculty     6327 Oct 11 09:34 Matrix3D.java
-rw-r--r--   1 dgerman  faculty     4580 Oct 11 09:35 XYZApp.class
-rw-r--r--   1 dgerman  faculty    13161 Oct 11 09:34 XYZApp.java
-rw-r--r--   1 dgerman  faculty     3762 Oct 11 09:35 XYZChemModel.class
burrowww.cs.indiana.edu%

Please note there is a warning. The reason is that this is a very old, very famous applet, using the very first (1.0) Java API. It does not matter, and once we know that we can move on. We will talk more about that later. If your class files are created, move to step 3. If not, what are you waiting for?

3. Prepare an .html file to distribute the applet.

Create an HTML file (call it index.html) in the same directory with the classes and the source code, and make sure it has an applet tag inside it that looks like this:
<applet code=XYZApp.class width=100 height=100>
  <param name =model 
         value=models/benzene.xyz> 
</applet> 
Notice the param tag. It communicates important data to the applet, without which the applet won't run. (Also, you're responsible for the rest of the HTML in the file).

4. Prepare data for the applet.

Create a directory models inside the folder that contains your Java applets code.
Next, copy all the *.xyz files from the following folder
/u/dgerman/fall2000/lab7
into your models directory. They contain important rendering information for the applet. The fact that the applet is taking this info from a file is part of the actual design of the applet (it's a decision of the original program writer).

Here's how I did it:

burrowww.cs.indiana.edu% pwd
/nfs/paca/home/user1/dgerman/apache/apache_1.3.22/htdocs/lab10
burrowww.cs.indiana.edu% ls -ld models
ls: models: No such file or directory
burrowww.cs.indiana.edu% mkdir models
burrowww.cs.indiana.edu% ls -ld models
drwxr-xr-x   2 dgerman  faculty      512 Oct 11 09:40 models
burrowww.cs.indiana.edu% cp /u/dgerman/fall2000/lab7/*.xyz models
burrowww.cs.indiana.edu% ls -l models
total 11
-rw-r--r--   1 dgerman  faculty     3674 Oct 11 09:40 HyaluronicAcid.xyz
-rw-r--r--   1 dgerman  faculty      269 Oct 11 09:40 benzene.xyz
-rw-r--r--   1 dgerman  faculty     2317 Oct 11 09:40 buckminsterfullerine.xyz
-rw-r--r--   1 dgerman  faculty      460 Oct 11 09:40 cyclohexane.xyz
-rw-r--r--   1 dgerman  faculty      170 Oct 11 09:40 ethane.xyz
-rw-r--r--   1 dgerman  faculty       66 Oct 11 09:40 water.xyz
burrowww.cs.indiana.edu%

5. Check your applet over the web.

You should see something like this.
Remember to use your mouse to rotate the 'benzene' molecule.
The HTML doesn't say anything about that (although it should).

6. Improve your HTML interface.

Describe what the page contains and what the user needs to do to interact with it.

7. Show all other molecule models.

I'll let you figure out how.

Now that we have seen this, let's include in our web page an applet from another site.

Take a look at this example from O'Reilly.

In this second part of the lab we prepare the installation of Tomcat.

For this, you should know up front, you will need two more port numbers.

They have been listed on the students page from the beginning of the semester.

So let's describe the process below.

TOMCAT INSTALLATION.

Create a folder where you will install tomcat.

burrowww.cs.indiana.edu% pwd
/nfs/paca/home/user1/dgerman/tomcat
burrowww.cs.indiana.edu%

Go there, and copy it from my public directory.

burrowww.cs.indiana.edu% pwd
/nfs/paca/home/user1/dgerman/tomcat
burrowww.cs.indiana.edu% cp /u/dgerman/public/jak*.gz . 
burrowww.cs.indiana.edu% ls -l
total 5160
-rw-r--r--   1 dgerman  faculty   5275338 Mar  7 12:09 jakarta-tomcat-4.0.4.tar.gz
burrowww.cs.indiana.edu%

Unzip it, and you're almost done.

gunzip *.gz

Check your quota, tar xvf, then remove the archive.

burrowww.cs.indiana.edu% which tar 
/usr/local/gnu/bin/tar
burrowww.cs.indiana.edu% tar xvf *.tar 
... 
jakarta-tomcat-4.0.4/bin/digest.bat
jakarta-tomcat-4.0.4/bin/bootstrap.jar
jakarta-tomcat-4.0.4/bin/startup.bat
jakarta-tomcat-4.0.4/bin/tomcat.exe
jakarta-tomcat-4.0.4/conf/catalina.policy
jakarta-tomcat-4.0.4/conf/server-noexamples.xml.config
jakarta-tomcat-4.0.4/conf/web.xml
jakarta-tomcat-4.0.4/conf/server.xml
jakarta-tomcat-4.0.4/conf/tomcat-users.xml
burrowww.cs.indiana.edu% quota -v
Disk quotas for dgerman (uid 10867):
Filesystem     usage  quota  limit    timeleft  files  quota  limit    timeleft
/nfs/paca/home/user1
               94490 100000 102400               2766      0      0            
burrowww.cs.indiana.edu% ls -ld *
drwxr-xr-x  11 dgerman  faculty      1024 Mar  1 14:49 jakarta-tomcat-4.0.4
-rw-r--r--   1 dgerman  faculty   5275338 Mar  7 12:09 jakarta-tomcat-4.0.4.tar
burrowww.cs.indiana.edu% rm *.gz
burrowww.cs.indiana.edu% quota -v
Disk quotas for dgerman (uid 10867):
Filesystem     usage  quota  limit    timeleft  files  quota  limit    timeleft
/nfs/paca/home/user1
               89330 100000 102400               2765      0      0            
burrowww.cs.indiana.edu%

For reference, latest version of Tomcat is always available here.

Let's now configure our server.

First we need to set a few environment variables.

Here's my ~/.cshrc

#
#  .cshrc  - This file is executed whenever a C shell is started.
#

# set the umask, which controls the permissions on new files you create/
# 022 denies write access to other people, but not read access.
# 077 denies read and write access to other people.

umask 022

# Set the PATH.  You can put your own personal commands in 
# your ~/bin directory.
#
# Note for use on Solaris:
#       Put /usr/ucb in your path before /usr/bin and /usr/sbin if you
#           want the bsd-ish versions of things like ps and df.
#       Put /usr/bin and /usr/sbin in your path before /usr/ucb if you
#           want the svr4-ish versions of things like ps and df.
#	If you don't know the difference between bsd and svr4, then
#       it is safe to just leave this as it is.
#
set path = ( ~/bin \
        /home/user1/mysql/bin /usr/local/gnu/bin /usr/bin \
        /usr/local/bin /usr/sbin /usr/ucb \
	/usr/bin/X11 /usr/openwin/bin /usr/dt/bin /opt/SUNWspro/bin \
	/usr/ccs/bin /usr/local/gnu/bin )

# This prevents programs from dumping a large file called "core"
# in the current directory when they crash.
# If you really do want these core files, delete this line.
limit coredumpsize 0

# Tell the shell how many previous commands to remember.  You can
# view the previous commands using the history command
set history=20

# Uncomment the following line if you don't want ^D to log you out
#set ignoreeof

# The following lines tell the shell to periodically check for new mail
# and print the messages "You have new mail" when mail arrives.
# This is a separate sort of mail notification from that provided
# by biff (see your .login file) 
setenv MAIL /var/mail/$USER
set mail=$MAIL

# You may want to set the prompt to something fancy.  The following
# line puts the hostname, your username, and the current command number
# in the prompt
#set prompt="[`whoami`@`hostname`:\!] " 
set prompt="`hostname`% "

# Select a default printer.  Under Solaris, some programs use PRINTER
# and others use LPDEST.  See the printers man page (man printers)
# for a list of available printers.
#setenv PRINTER psburrow
#setenv LPDEST psburrow

# You can create aliases for common commands.  The following line
# makes lls equivalent to 'ls -l'
alias lls ls -l

       setenv JAVA_HOME   /l/jdk

       setenv CATALINA_HOME /u/dgerman/tomcat/jakarta-tomcat-4.0.4

       setenv CLASSPATH   .:$CATALINA_HOME/common/lib/servlet.jar

# setenv startTomcat $TOMCAT_HOME/bin/startup.sh
# setenv stopTomcat  $TOMCAT_HOME/bin/shutdown.sh

Please make sure yours is compatible.

Here's a description of the Tomcat folders.

$CATALINA_HOME/bin         # contains the startup/shutdown scripts 
              /conf        # main config files: server.xml, a global web.xml 
              /server      # contains Tomcat Java Archive files 
              /lib         # JAR files that the servlet engine depends on 
              /common/lib  # JAR files shared between Tomcat components (server.jar) 
              /jasper      # JAR files for Jasper the JSP compiler 
              /logs        # contains Tomcat's log files 
              /src         # source files 
              /webapps     # where all web applications are deployed 
              /work        # where all servlets generated from JSP are placed

Here's my server.xml (which goes under $CATALINA_HOME/conf)

burrowww.cs.indiana.edu% pwd  
/nfs/paca/home/user1/dgerman/tomcat/jakarta-tomcat-4.0.4/conf
burrowww.cs.indiana.edu% ls -ld server.xml
-rw-r--r--   1 dgerman  faculty      2846 Mar 21 12:59 server.xml
burrowww.cs.indiana.edu% cat server.xml

<Server port="19201" shutdown="SHUTDOWN" debug="0">


  <Service name="Tomcat-Standalone">

    <Connector className="org.apache.catalina.connector.http.HttpConnector"
               port="19200" minProcessors="5" maxProcessors="75"
               enableLookups="true" 
               acceptCount="10" debug="0" connectionTimeout="60000"/>

    <Engine name="Standalone" defaultHost="localhost" debug="0">

      <Logger className="org.apache.catalina.logger.FileLogger"
              prefix="catalina_log." suffix=".txt"
              timestamp="true"/>

      <Realm className="org.apache.catalina.realm.MemoryRealm" />

      <Host name="localhost" debug="0" appBase="webapps" unpackWARs="true">

        <Valve className="org.apache.catalina.valves.AccessLogValve"
                 directory="logs"  prefix="localhost_access_log." suffix=".txt"
                 pattern="common"/>

        <Logger className="org.apache.catalina.logger.FileLogger"
                 directory="logs"  prefix="localhost_log." suffix=".txt"
	        timestamp="true"/>

        <Context path="/manager" docBase="manager" 
         debug="0" privileged="true"/>

        <Context path="/one" docBase="one" debug="0" reloadable="true" /> 

        <Context path="/examples" docBase="examples" debug="0"
                 reloadable="true" crossContext="true">
          <Logger className="org.apache.catalina.logger.FileLogger"
                     prefix="localhost_examples_log." suffix=".txt"
        	  timestamp="true"/>
          <Ejb   name="ejb/EmplRecord" type="Entity"
                 home="com.wombat.empl.EmployeeRecordHome"
               remote="com.wombat.empl.EmployeeRecord"/>

          <Environment name="maxExemptions" type="java.lang.Integer"
                      value="15"/>
          <Parameter name="context.param.name" value="context.param.value"
                     override="false"/>
          <Resource name="jdbc/EmployeeAppDb" auth="SERVLET"
                    type="javax.sql.DataSource"/>
          <ResourceParams name="jdbc/EmployeeAppDb">
            <parameter><name>user</name><value>sa</value></parameter>
            <parameter><name>password</name><value></value></parameter>
            <parameter><name>driverClassName</name>
              <value>org.hsql.jdbcDriver</value></parameter>
            <parameter><name>driverName</name>
              <value>jdbc:HypersonicSQL:database</value></parameter>
          </ResourceParams>
          <Resource name="mail/Session" auth="Container"
                    type="javax.mail.Session"/>
          <ResourceParams name="mail/Session">
            <parameter>
              <name>mail.smtp.host</name>
              <value>localhost</value>
            </parameter>
          </ResourceParams>
        </Context>

      </Host>

    </Engine>

  </Service>



</Server>
burrowww.cs.indiana.edu%

I might actually create this file for you, but let's look at it a bit:

it is a cleaned-up version of the file you obtain when you unpack
contains two new ports, you will be assigned two new ports soon
should be under $CATALINA_HOME/conf in your folder hierarchy

Likely, the server.xml files will be available from

/u/dgerman/public/a348/tomcats/

Get this file from

/u/dgerman/public/a348/tomcats/sampleServer.xml

Copy it where you should and make the changes to include your ports.

Once you have a customized server.xml in place start Tomcat.

burrowww.cs.indiana.edu% ps -ef | grep dgerman
 dgerman 16121 18943  0 08:00:02 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 16119 18943  0 08:00:02 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 25984 23278  0 13:31:34 pts/42   0:00 grep dgerman
 dgerman 16101 18943  0 08:00:02 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 18943     1  0   Feb 12 ?        0:03 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 23278 23006  0 12:05:26 pts/42   0:00 -csh
 dgerman 16141 18943  0 08:00:03 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 24021 18943  0 12:06:30 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 24034 18943  0 12:06:31 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 16100 18943  0 08:00:02 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
burrowww.cs.indiana.edu% $CATALINA_HOME/bin/startup.sh
Using CATALINA_BASE:   /nfs/paca/home/user1/dgerman/tomcat/jakarta-tomcat-4.0.4
Using CATALINA_HOME:   /nfs/paca/home/user1/dgerman/tomcat/jakarta-tomcat-4.0.4
Using CATALINA_TMPDIR: /nfs/paca/home/user1/dgerman/tomcat/jakarta-tomcat-4.0.4/temp
Using JAVA_HOME:       /l/jdk
burrowww.cs.indiana.edu% ps -ef | grep dgerman
 dgerman 16121 18943  0 08:00:02 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 26019     1  3 13:32:03 pts/42   0:05 /l/jdk/bin/../bin/sparc/native_threads/java -Djava.endorsed.dirs=/nfs/paca/home
 dgerman 16119 18943  0 08:00:02 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 16101 18943  0 08:00:02 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 18943     1  0   Feb 12 ?        0:03 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 23278 23006  0 12:05:26 pts/42   0:00 -csh
 dgerman 26033 23278  0 13:32:08 pts/42   0:00 grep dgerman
 dgerman 16141 18943  0 08:00:03 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 24021 18943  0 12:06:30 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 24034 18943  0 12:06:31 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
 dgerman 16100 18943  0 08:00:02 ?        0:00 /u/dgerman/apache/apache_1.3.22/bin/httpd
burrowww.cs.indiana.edu%

Then test it, here's mine.

Try the sample servlets, then the sample JSPs.

Then stop it, using:

$CATALINA_HOME/bin/shutdown.sh

Then start it again and let's develop a simple application, call it one.

burrowww.cs.indiana.edu% mkdir one
burrowww.cs.indiana.edu% mkdir one/WEB-INF
burrowww.cs.indiana.edu% mkdir one/WEB-INF/classes
burrowww.cs.indiana.edu% mkdir one/WEB-INF/lib
burrowww.cs.indiana.edu% du -a one
1       one/WEB-INF/classes
1       one/WEB-INF/lib
3       one/WEB-INF
4       one
burrowww.cs.indiana.edu% cd one
burrowww.cs.indiana.edu% ls
WEB-INF
burrowww.cs.indiana.edu% cd WEB-INF
burrowww.cs.indiana.edu% pwd
/nfs/paca/home/user1/dgerman/tomcat/jakarta-tomcat-4.0.4/webapps/one/WEB-INF
burrowww.cs.indiana.edu%

This structure is not random or accidental, and we will revisit (and review) it soon.

Then create your deployment descriptor web.xml as follows:

burrowww.cs.indiana.edu% pwd
/nfs/paca/home/user1/dgerman/tomcat/jakarta-tomcat-4.0.4/webapps/one/WEB-INF
burrowww.cs.indiana.edu% ls -l
total 3
drwxr-xr-x   2 dgerman  faculty       512 Mar 21 12:38 classes
drwxr-xr-x   2 dgerman  faculty       512 Mar 21 12:38 lib
-rw-r--r--   1 dgerman  faculty       340 Mar 21 12:46 web.xml
burrowww.cs.indiana.edu% cat web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
    "http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>


    <servlet>
        <servlet-name>howdy</servlet-name>
        <servlet-class>HelloWorld</servlet-class>
    </servlet>

</web-app>
burrowww.cs.indiana.edu%

Notice that the examples folder also contains a WEB-INF/web.xml inside.

You now need to create a ServletContext in server.xml

<Context path="/one" docBase="one" debug="0" reloadable="true" />

This line should be added in between the manager and the examples contexts.

We now only need to write, compile, deploy the servlet.

burrowww.cs.indiana.edu% pwd
/nfs/paca/home/user1/dgerman/tomcat/jakarta-tomcat-4.0.4/webapps/one/WEB-INF/classes
burrowww.cs.indiana.edu% ls -ld Hell*.java
-rw-r--r--   1 dgerman  faculty       344 Mar 21 13:03 HelloWorld.java
burrowww.cs.indiana.edu% cat HelloWorld.java
import javax.servlet.*;
import java.io.*;

public class HelloWorld extends GenericServlet {
    int n; 
    public void service(ServletRequest  req,
                        ServletResponse resp) throws  ServletException,
                        IOException {
        n = n + 1; 
        resp.setContentType("text/html");
        PrintWriter out = resp.getWriter();
        out.println("Counter is: " + n);
    }
}
burrowww.cs.indiana.edu% javac Hell*.java
burrowww.cs.indiana.edu% ls -ld *
-rw-r--r--   1 dgerman  faculty       841 Mar 21 13:03 HelloWorld.class
-rw-r--r--   1 dgerman  faculty       344 Mar 21 13:03 HelloWorld.java
burrowww.cs.indiana.edu%

To access it, use this URL:

http://burrowww.cs.indiana.edu:xxzzz/one/servlet/howdy

Bibliography for Tomcat, servlets, and J2EE:

Also tutorials on-line at java.sun.com

Tutorial One (Web Services)
Tutorial Two (J2EE Tutorial)

That should be enough to get us started (with a lot more to come).

To sum up, here's your...

A348/A548 LAB ASSIGNMENT TEN

Install Tomcat and make a change to the front page.
Also index on your Tomcat's main page the link to your servlet (presented above).
Also install the applet discussed above in both Tomcat and Apache.

Last updated: Apr 2, 2003 by Adrian German for A348/A548