Notes/Minute Paper for Nov. 29

1.  Define a context:
inside $CATALINA_HOME/webapps, create a directory - say, 'whoa'

2.  Give the context directory the proper structure by creating
subdirectories:
             whoa
               |
            WEB-INF
            /     \
        classes   lib

3.  Check that the context is accessible by checking the url:
       http://burrowww.cs.indiana.edu:#####/whoa
(where '#####' is your tomcat server port number)
If this doesn't work, stop and start the server (which you will have
to do anyway at some point) and check this again.  See step 9.

4.  Go up to the WEB_INF directory and create web.xml:

       1. modify the <servlet> tag, and
       2. the <servlet-mapping> tag.

In the example below the definition of Larry appears, it
is standard, there is also a more sophisticated definition
for some other servlet that we don't discuss:

<?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>Larry</servlet-name>
         <servlet-class>Larry</servlet-class>
     </servlet>
     <servlet-mapping>
         <servlet-name>Larry</servlet-name>
         <url-pattern>/servlet/Larry</url-pattern>
     </servlet-mapping>
     <servlet>
         <servlet-name>Fv2_3</servlet-name>
         <servlet-class>Two</servlet-class>
     </servlet>
     <servlet-mapping>
         <servlet-name>Fv2_3</servlet-name>
         <url-pattern>/servlet/Fancy</url-pattern>
     </servlet-mapping>

</web-app>

This step can be delayed until after you write your servlet,
but must be done before you can deploy your servlet on the web.

5.  Go into the classes directory and write the servlet (example):

unixprompt> pico Larry.java

       import java.io.*;
       import javax.servlet.*;
       import javax.servlet.http.*;

       public class Larry extends HttpServlet 
         {
         public void doGet(HttpServletRequest request,
                           HttpServletResponse response)
                  throws ServletException,
                         IOException
           {

           response.setContentType("text/html");
           PrintWriter out = response.getWriter();
           // other code, such as
           out.println("How are you?");

           }
 
         }

      (see Notes for lab 11 for another template)

6.  Go back to classes and compile the servlet:

       unixprompt> javac Larry.java

    Correct any syntax errors preventing compilation.

7.  Check that the servlet deploys by checking the url:

       http://burrowww.cs.indiana.edu:#####/whoa/servlet/Larry

8.  Redefine $CATALINA_HOME/conf/server.xml by adding a new context
definition inside the host tag.

<Server port="15477" shutdown="SHUTDOWN">
   <GlobalNamingResources>
     <!-- Used by Manager webapp -->
     <Resource name="UserDatabase" auth="Container"
               type="org.apache.catalina.UserDatabase"
        description="User database that can be updated and saved"
            factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
           pathname="conf/tomcat-users.xml" />
   </GlobalNamingResources>
   <Service name="Catalina">
     <Connector port="15476" />
     <Engine name="Catalina" defaultHost="localhost">
       <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
              resourceName="UserDatabase" />
       <Host name="localhost" appBase="webapps">
         <Context path="/whoa" docBase="whoa" debug="0" reloadable="true" />
         <Context path="/nov09" docBase="nov09" debug="0" reloadable="true" />
       </Host>
     </Engine>
   </Service>
</Server>

Until this step is done, the servlet will not update on the web even if you
change and recompile it.

9. Stop and start the server:

   unixprompt> $CATALINA_HOME/bin/shutdown.sh

Then check you're not running any more with:

   unixprompt> ps -ef | grep username (your username!) 

and if you are kill the process. Take the time now to delete the logs
in $CATALINA_HOME/logs (useful sometimes for debugging):

   unixprompt> rm $CATALINA_HOME/logs/*

Then restart Tomcat:

   unixprompt> $CATALINA_HOME/bin/startup.sh

Now the servlet will update on the web each time you recompile, so you
can edit and update conveniently.