Using the Jetty Webserver for Servlet Programming

This set of instructions will help you get started with running the Jetty servlet-supporting webserver, along with servlets that access the mSQL database via JDBC.
We will proceed in the following steps:
- Step 1: First install Java (if necessary) and test access to Java.
- Step 2: Install the Jetty webserver
- Step 3: Change the port number to your assigned port number.
- Step 4: Test a servlet.
- Step 5: Install mSQL and test.
- Step 6: Test JDBC via the mSQL JDBC driver.
- Step 7: Run a servlet with JDBC access.
- Step 8: Invoke a servlet URL from a form.
- Step 9: Now you're on your own.
This file contains instructions for steps 2 and 3.
NOTE:
- All instructions are given for a Unix system. These have been tried on both Solaris and Linux.
- For the examples, below we'll assume your username is "joe" and that the path to your home directory is "/home/joe"
- We'll assume the machine's name is "felix".
- Create a directory off of your main directory called, say, "java" into which you will place a whole bunch of things.
- In editing your login/shell/profile, we will assume you are running tcsh (preferably) or csh. If you are running ksh, you will need to edit your .profile file instead, and use commands appropriate to ksh (things like EXPORT).
IMPORTANT: you will be assigned two port numbers, one for administration and one for your webserver. Use ONLY these port numbers and nothing else.

Install Jetty

If you have enough diskspace (at least 15MB free) you can download the latest version of Jetty directly from Mortbay.

Alternatively, you can download a more compact version (2MB) from here: gzipped-tar-file.

Assuming you've created a special directory (say, "java") for these project, download the Jetty tarfile to the directory and extract it:

  % gunzip Jetty_compact.tar.gz
  % tar -xvf Jetty_compact.tar

This will create a subdirectory with the Jetty server.

Now, go to your shell file (.cshrc if you are using tcsh) and add the JETTY_HOME environment variable. For example, here's what you would add if the Jetty directory is /home/joe/java/Jetty-3.0.1

  setenv JETTY_HOME /home/joe/java/Jetty-3.0.1

This is what you would do in tcsh. In ksh, enter the following line in your .profile:

  export JETTY_HOME=/home/joe/java/Jetty-3.0.1

Next, add relevant Jetty libraries to your CLASSPATH variable. Recall, your CLASSPATH variable is what the Java compiler and interpreter use to access Java programs. For example, in tcsh, you would add the following lines after your current CLASSPATH as follows:

  setenv CLASSPATH ${CLASSPATH}:${JETTY_HOME}/lib/javax.servlet.jar
  setenv CLASSPATH ${CLASSPATH}:${JETTY_HOME}/lib/com.mortbay.jetty.jar
  setenv CLASSPATH ${CLASSPATH}:${JETTY_HOME}/lib/com.microstar.xml.jar

Modify a configuration file to add your own port number

Go to the $JETTY_HOME/etc directory and edit the file demo.xml. This is a plain text file XML file (XML is like HTML).

After the large comment, the first block of XML tags has a port number (usually set to 8080). Change the port number to your assigned port number.

Save the file.

Test your first servlet

Now you are ready to run Jetty and test a servlet.

First, we will run Jetty and try a default servlet:

Running Jetty:

Go to the $JETTY_HOME directory.
Run the Demo Jetty Server using:
```
        java com.mortbay.Jetty.Demo
      
```
Did it run? Did you remember to log in and out to re-set your CLASSPATH?
Next fire up a browser.
If your assigned port number is 8019, then type in the following URL into the browser: http://localhost:8019.
This should deliver an HTML file into your browser from the Jetty Server. Jetty is now working.
To stop Jetty: simply kill the server by typing ctrl-C in the window in which you fired up the server.

Testing Jetty with your own HTML:

First create any old HTML file, say test.html.
Put the file in $JETTY_HOME/docroot/test.html.
Now, use the URL http://localhost:8019/demo/test.html.

Next, Jetty often comes with a test-servlet called HelloWorldServlet. Let's try to access this servlet:

First, go to the $JETTY_HOME/servlets directory and see if the HelloWorldServlet.class is actually there.
If so, then type the URL http://localhost:8019/servlet/HelloWorldServlet into the browser.
This should cause "Hello World" to be displayed in the browser. It is the servlet code that writes "Hello World".

Now you are ready to type, compile and run your own servlet:

First, type it in (anywhere):

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

      public class HelloWorld extends HttpServlet {

        public void doGet (HttpServletRequest req, HttpServletResponse resp)
          throws ServletException, IOException
        {
          // Set the content type of the response.
          resp.setContentType ("text/html");

          // Create a PrintWriter to write the response.
          java.io.PrintWriter out = new PrintWriter (resp.getOutputStream());

          // The first part of the response.
          out.println ("");
          out.println (" Test ");
          out.println ("");

          // The greeting.
          out.println ("Yo, Hello World!");

          // Last part.
          out.println ("");
          out.println ("");
          out.close();

          // Screen I/O
          System.out.println ("Inside servlet ... servlet complete");
        }

        public void doPost (HttpServletRequest req, HttpServletResponse resp)
          throws ServletException, IOException
        {
          doGet (req, resp);
        }

      }

Compile and store the class file in the servlets directory:

      % javac HelloWorld.java
      % cp HelloWorld.class $JETTY_HOME/servlets/.

Now, fire up Jetty again and enter the URL (Use your port number):
```
      http://localhost:8019/servlet/HelloWorld
  
```
This should cause the HelloWorld servlet to execute and write the string to the browser.
If this did not work, do not proceed until you get this working.

Let's take this one step further:

Create the following test.html file:

        <html>
        <head><title> test </title></head>
        <body>
        <a href="http://localhost:8502/servlets/HelloWorld"> Click
          here for a classic greeting </a>
        </body>
        </html>

and save it in the docroot directory.

Now access the file in netscape with the URL http://localhost:8502/test.html
Click on the above link - the servlet should run.