myServlet WAR

C:\Temp> javac HelloServlet.java

Create the following directory structure for our web application, including moving the HelloServlet.class file to the indicated directory:

C:\Temp\
   myServletWAR\
      META-INF\
      WEB-INF\
         classes\
            HelloServlet.class
         web.xml

If HelloServlet was in a package of com.wpollock.myServletWAR, then HelloServlet.class would be placed in the directory myServletWAR\WEB-INF\classes\com\wpollock\myServletWAR\HelloServlet.class instead of in classes directly.

Some web applications may have additional files and directories.  You can add an index.html file to the top-level (document root) directory, as well as other files and directories such as Sources (containing the HelloServlet.java file), images, etc.  Please note that Tomcat, like Apache, uses case-sensitive URLs.

A copy of the web.xml deployment descriptor for myServletWAR can be found by clicking here.  Install this file in the subdirectory indicated in step 3.

XML files can be created and edited with any text editor, but you may wish to use this handy Microsoft XML Notepad editor to edit XML files.  XML files can be viewed directly using Microsoft Internet Explorer v5.5.

C:\Temp\myServletWAR> jar -cvf myServletWAR.war .

(Don't forget the period at the end of the command line!)  This will result in the WAR file similar to the one you can download here.  (This WAR also contains the servlet source code, a top level HTML file called index.html so you can see something reasonable if you use the URL http://localhost:8080/myServletWAR/, and a JSP example MilliSec.jsp.)

Note that the resulting JAR file is compressed as normal.  While this is not a problem for applets, it does slow down a server which must uncompress the WAR before using it.  An additional jar command line argument of 0 will cause the jar tool to create an uncompressed archive instead.  (When using Tomcat, your WAR files are expanded when the server first uses them and saves the result, so using compression is no problem.  However it might be a problem for other servlet containers, which may need to access the WAR each time.)

Note that Tomcat expands WAR files in the webapps directory.  When updating the WAR file you should delete the corresponding directory.  (The latest version of Tomcat has a setting to automatically do this when the WAR file is updated, but this causes Tomcat to run slower and this feature should not be relied upon.)

Some previous versions of Tomcat required a server configuration file to be updated in order to have Tomcat recognize a newly added web application.  In the current version this is no longer true.  It is enough to put the WAR file in the correct location.  As of Tomcat5, you no longer even need to restart!

Once this is done you should be able to run the servlet by using the proper URL shown at the top of this document.  In general the URL for a web application is the server part (including the port number) and the name of the web application.  This can be followed by any HTML or JSP documents that are part of the web application.  Note that with older versions of TomCat, servlets can be run directly by using a special URL.  In our example this would be:  http://localhost:8080/myServletWAR/servlet/HelloServlet.  However the way this worked led to security holes and other problems, and is no longer supported by default in newer versions of TomCat and shouldn't be used.