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*Originally taken from: http://wiki.apache.org/jakarta-tomcat/Tomcat/Howto*

Contents TableOfContents

How do I add a question to this page?

Anyone may edit this page to add their own content. That is why this page is part of a Wiki and not a hardcoded static file in the FAQ.

However, do not add questions without answers to this page. If you have a question about how to do something in Tomcat which has not been addressed yet, ask the [http://jakarta.apache.org/tomcat/faq/tomcatuser.html tomcat-user list]. Once you've figured out how to fix your problem, come back and update the Wiki to allow the rest of us to benefit from what you've learned!

How do I set up and run Tomcat on Macintosh OS X?

See ["TomcatOnMacOS"]

How do I set up multiple sites sharing the same war application/war file?

See CreateVirtualHosts

How do call tomcat ant tasks to deploy webapps?

See AntDeploy

How do I load a properties file?

Here are the two most popular ways::

  • Use a ResourceBundle. See the Java docs for the specifics of how the ResourceBundle class works. Using this method, the properties file must go into the WEB-INF/classes directory or in a jar file contained in the WEB-INF/lib directory.
  • Another way is to use the method getResourceAsStream() from the ServletContext class. This allows you update the file without having to reload the webapp as required by the first method. Here is an example code snippet, without any error trapping: 
        // Assuming you are in a Servlet extending HttpServlet
    // This will look for a file called "/more/cowbell.properties" relative
    // to your servlet Root Context
    InputStream is = getServletContext().getResourceAsStream("/more/cowbell.properties");
    Properties  p  = new Properties();
    p.load(is);
    is.close();


How do I log requests ?

See AccessLogValve

Can I set Java system properties differently for each webapp?

No. If you can edit Tomcat's startup scripts, you can add "-D" options to Java. But there is no way to add such properties in web.xml or the webapp's context.

How do I use log4j for all Tomcat log output?

To have Tomcat use log4j universally, place both log4j.jar and the Jakarta commons-logging.jar into the $TOMCAT_HOME/common/lib directory. Create your log4j properties file as $TOMCAT_HOME/common/classes/log4j.properties and configure the root logger. Here is the basic log4j.properties that I used to do this myself:

log4j.rootLogger=info, R
log4j.appender.R=org.apache.log4j.ConsoleAppender
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%-5p %-30.30c{1} %x - %m%n

If you only need to use log4j in your own web app, just include log4j (and any log4j properties file) in your WAR file.

How do I configure Tomcat Connectors?

On the Tomcat FAQ, there is a list of Other Resources which should have information pointing you to the relevant pages.

Each connector has its own configuration, and its own set up. Check them for more information.

In particular, here are a number of locations for Tomcat Connectors:

  • [http://jakarta.apache.org/tomcat/connectors-doc/index.html Tomcat Connectors Documentation]

  • [http://jakarta.apache.org/tomcat/connectors-doc/faq.html Tomcat Connectors FAQ]

  • [http://jakarta.apache.org/tomcat/tomcat-4.1-doc/jk2/config/apache.html Configuring Tomcat Connectors for Apache]

The following excellent article was written by Mladen Turk. He is a Developer and Consultant for JBoss Inc in Europe, where he is responsible for native integration. He is a long time commiter for Jakarta Tomcat Connectors, Apache Httpd and Apache Portable Runtime projects.

Fronting Tomcat with Apache or IIS - Best Practices

John Turner has an excellent page about [http://johnturner.com/howto/apache-tomcat-howto.html Using Apache HTTP with Apache Tomcat]. Several different connectors have been built, and some connector projects have been abandoned (so beware of old documentation).

How do I configure Tomcat to work with IIS and NTLM?

See ["TomcatNTLM"]

Tomcat crashed! What do I do now?

These steps are in no particular order ...

1.#0 Read the Tomcat FAQ

  1. Read the Tomcat RELEASE NOTES - there is something about Linux in it
  2. First look at the stack traces. I hope a stack trace was produced before the failure aborted the JVM process. After you get a few stack traces, see if a pattern appears. Trace back to source code if needed.
  3. Patch (or unpatch!) the operating system as needed.
  4. Patch (or unpatch!) the JVM (Java Virtual Machine).
  5. Linux Problem? - read the RELEASE NOTES!
  6. Look at commercial vendor support for other servlet engines. Sometimes the problem is universal regardless of servlet engine and may be a JVM/OS/application code issue
  7. Search Google for web pages - maybe someone else had this problem. I'll bet they did.
  8. Search Google news groups
  9. If the JVM is from a commercial vendor, (eg: IBM, HP) check their release notes and news groups
  10. Using a database? Make sure JDBC type 4 drivers are used. Check their release notes.
  11. Tweak JVM memory parameters. Setting memory too high can be as bad as having memory too low. If your memory settings are set too high, Java 1.3 JVMs may freeze while waiting for the entire garbage collection to finish. Also if the JVM has too much memory, if may be starving other resources on the machine which are needed which may be causing unforeseen exceptions. In a nutshell, throwing more memory doesn't always solve the problem!
  12. Turn off the Java JIT compiler. See the Java Docs on how to do this.


How do I share sessions across web apps?

You cannot share sessions directly across web apps, as that would be a violation of the Servlet Specification. There are workarounds, including using a singleton class loaded from the common classloader repository to hold shared information, or putting some of this shared information in a database or another data store. Some of these approaches have been discussed on the [http://jakarta.apache.org/tomcat/faq/tomcatuser.html tomcat-user mailing list], whose archives you should search for more information.

Sharing sessions across containers for clustering or replication purposes is a different matter altogether.

Why doesn't the netbeans example build for me?

I have found two issues with the build.xml provided here: http://jakarta.apache.org/struts/faqs/netbeans.html

First, add this to the top of your properties:

<property environment="env" />

Next find this line in the "war" target:

<classes dir="${build.dir}" includes="**/*.properties" />

Change it so it reads like this:

<classes dir="${src.dir}" includes="**/*.properties" />

Now it will work!

I'm encountering classloader problems when using JNI under Tomcat

The important thing to know about using JNI under Tomcat is that one cannot place the native libraries OR their JNI interfaces under the WEB-INF/lib or WEB-INF/classes directories of a web application and expect to be able to reload the webapp without restarting the server. The class that calls System.loadLibrary(String) must be loaded by a classloader that is not affected by reloading the web application itself.

Thus, if you have JNI code that follows the convention of including a static initilaizer like this:

class FooWrapper {
    static {
        System.loadLibrary("foo");
    }

    native void doFoo();
  }

then both this class and the shared library should be placed in the $CATALINA_HOME/shared/lib directory.

Note that under Windows, you'll also need to make sure that the library is in the java.library.path. Either add %CATALINA_HOME%\shared\lib to your Windows PATH environment variable, or place the DLL files in another location that is currently on the java.library.path. There may be a similar requirement for UNIX based system (I haven't checked), in which case you'd also have to add $CATALINA_HOME/shared/lib to the PATH environment variable. (Note: I'm not the original author of this entry.)

The symptom of this problem that I encountered looked something like this -

    java.lang.UnsatisfiedLinkError: Native Library WEB-INF/lib/libfoo.so already loaded in another classloader
        at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1525)

If the UnsatisfiedLinkError is intermittent, it may be related to Tomcat's default session manager. It restored previous sessions at startup. One of those objects may load the JNI library. Try stopping the Tomcat JVM, deleting the SESSIONS.ser file, then starting Tomcat. You may consider changing the session persistence manager at this time.

Note that Tomcat 6.0.14 the $CATALINA_HOME/shared/lib directory does not exist. You will need to add this and you will need to edit $CATALINA_HOME/conf/catalina.properties so that the shared.loader line looks like this shared.loader=$CATALINA_HOME/shared/lib

How can I access members of a custom Realm or Principal?

When you create a custom subclass of RealmBase or GenericPrincipal and attempt to use those classes in your webapp code, you'll probably have problems with ClassCastException. This is because the instance returned by request.getUserPrincipal() is of a class loaded by the server's classloader, and you are trying to access it through you webapp's classloader. While the classes maybe otherwise exactly the same, different (sibling) classloaders makes them different classes.

This assumes you created a MyPrincipal class, and put in Tomcat's server/classes (or lib) directory, as well as in your webapp's webinf/classes (or lib) directory. Normally, you would put custom realm and principal classes in the server directory because they depend on other classes there.

Here's what you would like to do, but it throws ClassCastException:

MyPrincipal p = request.getUserPrincipal();
String emailAddress = p.getEmailAddress();

Here are 4 ways you might get around the classloader boundary:

1) Reflection

Principal p = request.getUserPrincipal();
String emailAddress = p.getClass().getMethod("getEmailAddress", null).invoke(p, null);

2) Move classes to a common classloader

You could put your custom classes in a classloader that is common to both the server and your webapp - e.g., either the "common" or bootstrap classloaders. To do this, however, you would also need to move the classes that your custom classes depend on up to the common classloader, and that seems like a bad idea, because there a many of them and they a core server classes.

3) Common Interfaces

Rather than move the implementing custom classes up, you could define interfaces for your customs classes, and put the interfaces in the common directory. You're code would look like this:

public interface MyPrincipalInterface extends java.security.Principal {
  public String getEmailAddress();
}

public class MyPrincipal implements MyPrincipalInterface {
...
  public String getEmailAddress() {
    return emailAddress;
  }
}

public class MyServlet implements Servlet {
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    MyPrincipalInterface p = (MyPrincipalInterface)request.getUserPrincipal();
    String emailAddress = p.getEmailAddress();
...
}

Notice that this method gives you pretty much the webapp code you wanted in the first place

4) Serializing / Deserializing

You might want to try serializing the response of 'request.getUserPrincipal()' and deserialize it to an instance of [webapp]MyPrincipal.

Setting up SSL

Threads from the [http://jakarta.apache.org/tomcat/faq/tomcatuser.html tomcat-user list]

Using Verisign:

Using ["OpenSSL"]:

A description of "what SSL is all about anyway":

HowTo SSL Client Authentication with Fallback to FORM Authentication

See ["SSLWithFORMFallback"]

How do I set up another tomcat service on Windows, sharing the same Tomcat Home ?

This script sets up a a tomcat base directory and calls tomcat5.exe to create a windows service which will use the tomcat home given for the binaries and tomcat base you create See ["TomcatCreateWindowsService"]

How do I install Tomcat as a service under Unix?

Create a shell program to start Tomcat automatically. Each UNIX varies in how it starts up automatic services, but there are two main variants:

BSD::In a typical BSD system, there are a series of start up scripts in /etc starting with rc.. Look for, or create, a file called /etc/rc.local and enter the appropriate instructions to start up Tomcat there as a shell script.

System V::In a typical UNIX System V setup, there is a directory containing startup scripts, and other directories which contain links to these startup scripts. Create the appropriate startup script for your setup, then create the appropriate links.

For more information on each, check your system documentation.

(lightbulb) It also makes a lot of sense to use the JavaServiceWrapper.

How do I get direct access to a Tomcat Realm?

Credit: This code is from a post by Yoav Shapira http://www.yoavshapira.com in the user list

Sometimes access directly into the Tomcat realm object is needed; to do, this the following code can be used. Be aware, however, that by using this, your application is relying on a Tomcat extension and is therefore non-standard.

Note that in order for this to work the Context of the web application in question needs to have its privileged attribute set to "true", otherwise web apps do not have access to the Tomcat classes.

Server server = ServerFactory.getServer();
//Note, this assumes the Container is "Catalina"
Service service = server.findService("Catalina");
Engine engine = (Engine) service.getContainer();
Host host = (Host) engine.findChild(engine.getDefaultHost());
//Note, this assumes your context is "myContext"
Context context = (Context) host.findChild("myContext");
Realm realm = context.getRealm();

How do I make Tomcat startup faster?

See ["HowTo/FasterStartUp"]

How do I contribute to Tomcat's documentation?

  • Download the source bundle or grab the source XML file from CVS. The docs are in the jakarta-tomcat-catalina CVS module, in the webapps/docs subdirectory. They are in XML format and get processed into the HTML documentation as part of the Tomcat release.
  • Edit the documentation XML file(s) as you wish. The xdocs format is self-explanatory: use normal HTML markup, and add <section> or <subsection> tags as you see fit. Look at the existing docs as exampels. Make sure you use valid XML markup.
  • Open a Bugzilla enhancement item with the explanation of your enhancements, and attach a diff -u format of your patch. We will evaluate and commit your patch as needed. Note that the Tomcat web site is updated with every release, so that documentation changes will not be visible as soon as you submit your Bugzilla item.
  • If you're interested in previewing your changes, you will need to follow the directions for building Tomcat yourself. The docs will be generated in the webapps/tomcat-docs directory just like with any normal Tomcat distributions.
  • If you'd like to get documentation up and visible to the world before the next Tomcat release, use this wiki site.

How do I override the default home page loaded by Tomcat?

After successfully installing Tomcat, you usually test it by loading http://localhost:8080 . The contents of that page are compiled into the index_jsp servlet. The page even warns against modifying the index.jsp files for this reason. Luckily, it is quite easy to override that page. Inside $TOMCAT_HOME/conf/web.xml there is a section called <welcome-file-list> and it looks like this:

    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

The default servlet attempts to load the index.* files in the order listed. You may easily override the index.jsp file by creating an index.html file at $TOMCAT_HOME/webapps/ROOT. It's somewhat common for that file to contain a new static home page or a redirect to a servlet's main page. A redirect would look like:

<html>

<head>
<meta http-equiv="refresh" content="0;URL=http://mydomain.com/some/path/to/servlet/homepage/">
</head>

<body>
</body>

</html>

This change takes effect immediately and does not require a restart of Tomcat.

How do I edit the default JSP home page loaded by Tomcat?

See ["EditDefaultJSPPage"]

How do I redirect System.out and System.err to my web page?

I have met a situation where I needed to redirect a portion of standard ouput (System.out, STDOUT) and standard error (System.err, STDERR) to my web page instead of a log file. An example of such an application is a compiler research platform that our resarch team is putting online for anybody to be able to quickly compile-test their programs on line. Naturally, the compilers dump some of their stuff to STDERR or STDOUT and they are not web application .jar. Thus, I needed badly these streams related to the compiler output to be redirected to my web editor interface. Having found no easy instructions on how to do that lead me writing up this quick HOWTO. The HOWTO is based on Servlets, but similar arrangements can be done for JSPs. The below example shows the essentials, with most non-essentials removed.

public class WebEditor
extends HttpServlet
{
 ...
	public void doGet
	(
		HttpServletRequest poHTTPRequest,
		HttpServletResponse poHTTPResponse
	)
	throws IOException, ServletException
	{
		poHTTPResponse.setContentType("text/html");

		ServletOutputStream out = poHTTPResponse.getOutputStream();

		out.println("<html>");
		out.println("<body>");
		out.println("<head>");
		out.println("<title>WebEditor Test $Revision: 1.6 $</title>");
		out.println("</head>");
		out.println("<body>");
		out.println("<h3>WebEditor Test $Revision: 1.6 $</h3>");
		out.println("<hr />");

		// Backup the streams
		PrintStream oStdOutBackup = System.out;
		PrintStream oStdErrBackup = System.err;

		// Redired STDOUT and STDERR to the ServletOuputStream
		System.setOut(new PrintStream(out));
		System.setErr(new PrintStream(out));


		try
		{
			// ... call compiler here that produces
			// tons of STDOUT/STDERR messages ...
		}
		catch(Exception e)
		{
			out.println(e.toString());
		}

		// Restore original STDOUT and STDERR
		System.setOut(oStdOutBackup);
		System.setErr(oStdErrBackup);

		out.println("<hr />");
		out.println("</body>");
		out.println("</html>");
	}
}

A few caveats arise, as for instance while the System.out and System.err are deirected as per above, no logging of these is done to files. You will need more legwork to do to make the additional logging. It is important to backup and restore the original streams as the above example does. Also, notice the use of getOutputStream():
when this method is called, the getWriter() method can no longer be used in the same response object.

Corrections and comments are most welcome!

How to run Tomcat without root priviledges?

Is there a way to allow normal user(non-root) to start/stop the tomcat server. Tried assigning permision, did not work. Read thru some articles, stated that only root has permission to port below 1025. How can i allow a non-root user to do so ? thks in adv. (smile)

  • malathi ranjit singh----

One way is to put Apache httpd with mod_jk before your Tomcat servers, and use ports >=1024 in the Tomcat(s). Since we do it that way, it's the only way I know.

BTW, you should read the 1st howto. (wink)

Another method is to use SetUID scripts (assuming you have the capability) to do this. Here's how I do it.

Create a file called foo.c with this content (replace "/path/startupscript" with the tomcat startup script):

#include <unistd.h>
#include <stdlib.h>

int main( int argc, char *argv[] )
{
if ( setuid( 0 ) != 0 ) perror( "setuid() error" );

printf( "Starting ${APPLICATION}\n" );
execl( "/bin/sh", "sh", "/path/startupscript", 0 );
return 1;
}

Run the following as root (replacing tmp with whatever you want the startup script to be and replacing XXXXX with whatever group you want to be able to start and stop tomcat:

gcc tmp.c -o tmp chown root:XXXXX tmp chmod ugo-rwx tmp chmod u+rwxs,g+rx tmp

Now members of the tomcat group should be able to start and stop tomcat. One caveat though, you need to ensure that that your tomcat startup script is not writable by anyone other than root, otherwise your users will be able to insert commands into the script and have them run as root (very big security hole).

  • A another way is to use Iptables to redirect Port 80 and 443 to user ports (>1024)
  • /sbin/iptables -A FORWARD -p tcp --destination-port 443 -j ACCEPT
  • /sbin/iptables -t nat -A PREROUTING -j REDIRECT -p tcp --destination-port 443 --to-ports 8443
  • /sbin/iptables -A FORWARD -p tcp --destination-port 80 -j ACCEPT
  • /sbin/iptables -t nat -A PREROUTING -j REDIRECT -p tcp --destination-port 80 --to-ports 8080

/sbin/iptables-save or /etc/init.d/iptables save

BSD-based Unix systems such as Mac OS X use a tool similar to iptables, called ipfw (for Internet Protocol Fire Wall). This tool is similar in that it watches all network packets go by, and can apply rules to affect those packets, such as "port-forwarding" from port 80 to some other port such as Tomcat's default 8080. The syntax of the rules is different than iptables, but the same idea. For more info, google and read the man page. Here is one possible rule to do the port-forwarding:

sudo ipfw add 100 fwd 127.0.0.1,8080 tcp from any to any 80 in

How do I debug a Tomcat application?

There is nothing magical about debugging a Tomcat application. All you need is an IDE and two environment variables.

  • If you have not already done so begin by creating a new Tomcat context for your application. Navigate to TOMCAT_HOME\conf\Catalina\localhost and create a new file, say, myapp.xml. This will become part of your url, so to access your app you'll have to type *http://localhost:8080/myapp*.
  • Enter the following in myapp.xml: 
<Context docBase="c:/worskpace/myapp/WebRoot" path="/HelloWorld"/>

This assumes you have a web application containing WEB-INF in c:/workspace/myapp/WebRoot

  • Create two environment variables: 
C:\>set JPDA_ADDRESS=1044
C:\>set JPDA_TRANSPORT=dt_socket
  • Now, you can launch Tomcat with these debug options: 
TOMCAT_HOME\bin\>catalina jpda start
  • Use your IDE to connect to Tomcat through port 1044

If Eclipse happens to be your IDE of choice, you can get more information at [http://www.jacoozi.com/index.php?option=com_content&task=view&id=119&Itemid=134 Remote Debugging with Eclipse (Jacoozi Article)].

How do I enable Server Side Includes (SSI)?

two things have to be done for tomcat to aknowledge SSI scripts:

  1. Rename $CATALINA_BASE/server/lib/servlets-ssi.renametojar to $CATALINA_BASE/server/lib/servlets-ssi.jar.

2. Uncomment the section of web.xml found in $CATALINA_BASE/conf/web.xml that deals with SSI. it looks like this when it is uncommented:

    <servlet>
        <servlet-name>ssi</servlet-name>
        <servlet-class>
          org.apache.catalina.ssi.SSIServlet
        </servlet-class>
        <init-param>
          <param-name>buffered</param-name>
          <param-value>1</param-value>
        </init-param>
        <init-param>
          <param-name>debug</param-name>
          <param-value>0</param-value>
        </init-param>
        <init-param>
          <param-name>expires</param-name>
          <param-value>666</param-value>
        </init-param>
        <init-param>
          <param-name>isVirtualWebappRelative</param-name>
          <param-value>0</param-value>
        </init-param>
        <load-on-startup>4</load-on-startup>
    </servlet>

additional information can be found at:
[http://tomcat.apache.org/tomcat-5.5-doc/ssi-howto.html]

How do I connect to a Websphere MQ (MQ Series) server using JMS and JNDI?

Basically, this works just as described in
[http://tomcat.apache.org/tomcat-5.5-doc/jndi-resources-howto.html]: Within your application, you are using the standard JNDI and JMS API calls. In web.xml (the container independent application descriptor), you specify resource references (stub resources). And in context.xml (the container specific application descriptor), you are actually configuring the JMS connection.

More to the point. Here's some example code, which might be added to a Servlet. The example is sending a message to an MQ server:

    import javax.jms.Queue;
    import javax.jms.QueueConnection;
    import javax.jms.QueueConnectionFactory;
    import javax.jms.QueueSender;
    import javax.jms.QueueSession;
    import javax.jms.Session;
    import javax.jms.TextMessage;
    import javax.naming.Context;
    import javax.naming.InitialContext;

    Context ctx = (Context) new InitialContext().lookup("java:comp/env");
    QueueConnectionFactory qcf = (QueueConnectionFactory) ctx.lookup("jms/MyQCF");
    QueueConnection qc = qcf.createQueueConnection();
    Queue q = (Queue) ctx.lookup("jms/MyQ");
    QueueSession qs = qc.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
    TextMessage tm = qs.createTextMessage();
    tm.setText("Hi, there!");
    QueueSender sender = qc.createSender();
    sender.send(tm);
    sender.close();
    qs.close();
    qc.close();

Note the following:

  1. I have intentionally omitted proper resource handling. For example, one ought to ensure that qc.close() is always called by using a try { .. } finally { ..} block.

2. The code contains absolutely no references to com.ibm.mq*.jar.

3. There are only two items, which need configuration: "jms/MyQCF", and "jms/MyQ". We'll find them again in web.xml, and context.xml.

We have now written the code. Additionally, our web application needs the following files, and directories:

    +--META-INF
    |  +--- context.xml
    +--WEB-INF
       +--- web.xml
       +--- lib
            +--- com.ibm.mq.jar
            +--- com.ibm.mqjms.jar
            +--- connector.jar
            +--- dhbcore.jar
            +--- geronimo-j2ee-management_1.0_spec-1.0.jar
            +--- geronimo-jms_1.1_spec-1.0.jar

The application descriptor web.xml looks just the same as usual, with the exception of the following lines:

  <resource-env-ref>
    <resource-env-ref-name>jms/MyQCF</resource-env-ref-name>
    <resource-env-ref-type>javax.jms.QueueConnectionFactory</resource-env-ref-type>
  </resource-env-ref>

  <resource-env-ref>
    <resource-env-ref-name>jms/MyQ</resource-env-ref-name>
    <resource-env-ref-type>javax.jms.Queue</resource-env-ref-type>
  </resource-env-ref>

This is simply telling, that the items "jms/MyQCF", and "jms/MyQ" exist, and are instances of QueueConnectionFactory, and Queue, respectively. The actual configuration is in context.xml:

   <Resource
      name="jms/MyQCF"
      auth="Container"
      type="com.ibm.mq.jms.MQQueueConnectionFactory"
      factory="com.ibm.mq.jms.MQQueueConnectionFactoryFactory"
      description="JMS Queue Connection Factory for sending messages"
      HOST="<mymqserver>"
      PORT="1414"
      CHAN="<mychannel>"
      TRAN="1"
      QMGR="<myqueuemanager>"/>
   <Resource
      name="jms/MyQ"
      auth="Container"
      type="com.ibm.mq.jms.MQQueue"
      factory="com.ibm.mq.jms.MQQueueFactory"
      description="JMS Queue for receiving messages from Dialog"
      QU="<myqueue>"/>

Basically, you just have to enter your values for <myqserver> (the WebSphere MQ servers host name), <mychannel> (the channel name), <myqueuemanager> (the queue manager name), and <myqueue> (the queue name). Both these values, the associated names (HOST, PORT, CHAN, ...), and their collection is truly MQ specific. For example, with ActiveMQ, you typically have a broker URL, and a broker name, rather than HOST, PORT, CHAN, ...

The main thing to know (and the reason why I am writing this, because it took me some hours to find out): How do I know the property names, their meaning, and possible values? Well, there is an excellent manual, called "WebSpere MQ Using Java". It should be easy to find by entering the title into Google. The manual contains a section, called "Administering JMS objects", which describes the objects being configured in JNDI. But the most important part is the subsection on "Properties", which contains all the required details.

}}}

How do I use DataSources with Tomcat?

See UsingDataSources

How do I install the Administration web app?

If you install Tomcat 5.5 binaries, the Administration web app is not bundled with it; this describes how to add the Administration web app to your Tomcat 5.5 installation. (Tomcat 4.1 comes with the Administration web app as part of the binary).

The following refers to a Tomcat 5.5 set up on Windows 2000, so your path names will be different on *nix platforms. In this example, Tomcat 5.5.17 in installed in c:\Program Files\Apache Software Foundation\Tomcat 5.5 (this is my CATALINA_HOME).

  1. Unzip or untar (be careful to use GNU tar) the file containing the administration web app files (eg. apache-tomcat-5.5.17-admin.zip) to a temporary directory, eg. c:\temp.

  2. Copy c:\temp\apache-tomcat-5.5.17\conf\Catalina\localhost\admin.xml to the directory c:\Program Files\Apache Software Foundation\Tomcat 5.5\conf\Catalina\localhost.
  3. Copy the entire directory tree c:\temp\apache-tomcat-5.5.17\server\webapps\admin

to the directory c:\Program Files\Apache Software Foundation\Tomcat 5.5\server\webapps. This is an overlay, so \server\webapps is just pointing you to the \server\webapps, and the admin directory with its contents will be the only thing you see added there.

  1. Add a line to your c:\Program Files\Apache Software Foundation\Tomcat 5.5\conf\tomcat-users.xml file so that you have a user who has admin role. For example, add this line just before the last line (containing </tomcat-users>) of the file:
    <user username="admin" password="makesomethingup" roles="admin,manager"/>
  2. Restart Tomcat.
  3. Now when you visit _http://localhost:8080/admin_ you should see a page that asks for a user name and password. If you still see the "no longer loaded" error message in your browser, you must either force a full reload of the web page (in Firefox, hold down Shift key while clicking on the Reload button) or just restart your browser completely.

How do I add JARs or classes to the common classloader without adding them to $CATALINA_HOME/common/lib?

Edit the file catalina.properties under $CATALINA_BASE/conf; there is a property called common.loader to which you can add additional paths to find JARs or classes for the common classloader.

How do I get Tomcat to start when it says it can't find the file 'setclasspath.sh'?

If Tomcat was working fine the first few times after installation but suddenly refuses to start up and gives the following error message:

$ ./startup.sh
Cannot find /path/to/tomcat/bin/setclasspath.sh
This file is needed to run this program

Then all you need to do is to include the complete paths for the BASEDIR and CATALINA_HOME variables in the files setclasspath.sh and catalina.sh respectively.

This should be done even if CATALINA_HOME has been defined and exported previously on the command line and/or in /etc/profile as well. Moreover, this error message persists even though the file setclasspath.sh is present in Tomcat's bin directory.

$ echo "BASEDIR=/path/to/tomcat" >> setclasspath.sh
$ echo "CATALINA_HOME=/path/to/tomcat" >> catalina.sh

How do I authenticate Manager access via JNDI to Active Directory for multiple Tomcat instances?

ADS insists that the CN of every group be unique, but the Manager app. always uses the group CN=manager. The default can be changed, but it's hard to find and you have to do it over every time you upgrade. Instead, pick an attribute other than the common name – for example, "description" – that doesn't have to be unique, name it as the RoleName attribute of the Realm (in server.xml, which you'll be editing anyway), and set that attribute to "manager" in each group you create. Create an OU for each Tomcat instance's groups and give that OU's DN as the RoleBase in that instance's server.xml. Create a uniquely-named group in each instance's OU with the chosen attribute ("description" for example) set to "manager".

How do I check whether Tomcat is UP or DOWN? There is no status command

Unfortunately, the org.apache.catalina.util.ServerInfo class does not determine if Tomcat is UP or DOWN. It is possible to do an HTTP GET on the root url but this is not accurate. In my case I sometimes use a regular Apache HTTPd to display a maintainence message while upgrading, etc. and using that method would give false positives.

The correct way to do determine status is to parse the admin port from server.xml and see if we can connect to it. If we can then the Tomcat is UP otherwise it is DOWN.

Here is my code to do this. Consider it public domain and use it as you see fit. Tomcat makes a note of this connection with something like this on the console.

May 1, 2007 5:10:35 PM org.apache.catalina.core.StandardServer await
WARNING: StandardServer.await: Invalid command '' received

Ideally this should be incorporated into org.apache.catalina.util.ServerInfo by some committer. In addition to the shutdown command they should add commands like status (UP or DOWN) and uptime in the await method of org.apache.catalina.core.StandardServer 

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;

/**
 * Check to see if Tomcat is UP/DOWN.
 *
 * This parses the server.xml file for the Tomcat admin port and see if
 * we can connect to it. If we can, then the Tomcat is UP otherwise it
 * is DOWN
 *
 * It is invoked as follows:
 *    java -Dcatalina.base=c:/tomcat-6.0.10 CatalinaStatus
 *
 * It can also (optionally) shutdown the Tomcat by adding the shutdown
 * command line parameter as follows:
 *
 *    java -Dcatalina.base=c:/tomcat-6.0.10 CatalinaStatus shutdown
 *
 * @author Shiraz Kanga <skanga at yahoo.com>
 */
public class CatalinaStatus
{
  /**
   * Pathname to the server configuration file.
   */
  protected static String configFile = "conf/server.xml";
  protected static String serverShutdown;
  protected static int serverPort;

  /**
   * The application main program.
   *
   * @param args Command line arguments
   */
  public static void main (String args[])
  {
    Document configDom = getXmlDom (configFile ());
    parseDocument (configDom);
    // System.out.println ("Catalina.serverPort: " + serverPort);
    // System.out.println ("Catalina.serverShutdown: " + serverShutdown);

    // Stop the existing server
    try
    {
      Socket localSocket = new Socket ("127.0.0.1", serverPort);
      System.err.println ("Server status:  UP");
      if ((args.length > 0) && (args[0].equalsIgnoreCase ("shutdown")))
      {
        System.out.println ("Tomcat shutdown initiated" );
        doShutdown (localSocket);
      }

      localSocket.close ();
    }
    catch (IOException e)
    {
      System.err.println ("Server status:  DOWN");
      System.exit(1);
    }
  }

  /**
   * Return a File object representing our configuration file.
   */
  protected static File configFile ()
  {
    File confFile = new File (configFile);
    if (!confFile.isAbsolute())
      confFile = new File (System.getProperty ("catalina.base"), configFile);
    return (confFile);
  }

  /**
   * Parses an XML file and returns a DOM document.
   */
  public static Document getXmlDom (File fileName)
  {
    try
    {
      // Create a builder factory
      DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance ();

      // Create the builder and parse the file
      Document doc = factory.newDocumentBuilder ().parse (fileName);
      return doc;
    }
    catch (SAXException e)
    {
      // A parsing error occurred; the xml input is not valid
      e.printStackTrace ();
    }
    catch (ParserConfigurationException e)
    {
      e.printStackTrace ();
    }
    catch (IOException e)
    {
      e.printStackTrace ();
    }
    return null;
  }

  /**
   * Extract the server port & shutdown command from the DOM
   */
  private static void parseDocument (Document configDom)
  {
    //get the root element which is Server Eg: <Server port="8005" shutdown="SHUTDOWN">

    Element docEle = configDom.getDocumentElement ();
    serverPort = new Integer (docEle.getAttribute ("port")).intValue ();
    serverShutdown = docEle.getAttribute ("shutdown");
  }

  /**
   * Send the shutdown command to the server
   */
  private static void doShutdown (Socket localSocket)
  {
    try
    {
      OutputStream outStream = localSocket.getOutputStream ();

      for (int i = 0; i < serverShutdown.length (); i++)
        outStream.write (serverShutdown.charAt (i));
      outStream.flush ();
      outStream.close ();
    }
    catch (IOException e)
    {
      System.out.println ("ERROR: I/O Exception during server shutdown.");
      e.printStackTrace ();
    }
  }
}
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