Some of the most frequently asked questions regarding Servlet development on Tomcat. Some questions may also be answered in the ServletsFaq and the JspFaq.
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The Official Tomcat Wiki answers many questions, and is an excellent starting point for further research: http://wiki.apache.org/tomcat/HowTo
Tomcat (startup scripts) looks for the presence of JAVA_HOME environment variable to pick up the Java version to use. You can set the JAVA_HOME appropriately to point to the version of Java, you want Tomcat to use.
Some of the previous discussions, in our Tomcat Forum, on how this can be done:
The Tomcat Manager application is essential to listing and controlling the contexts (web apps) managed by the container. The Manager application ships with Tomcat, but you must create a privileged user in order to user the application.
Open the file tomcat-users.xml file in Tomcat's conf folder as add the following line if it is not already there:
The add the following:
Be sure to substitute appropriate usernames and passwords.
Restart Tomcat and hit the URL:
You should see the list of running web applications.
Tomcat Admin Application
Starting Tomcat 5.5, the "admin" application in Tomcat is not shipped by default. Tomcat Admin Application is a previous discussion on how to download and deploy the admin application.
How to define a context name in Tomcat
One of the frequently asked questions in Tomcat is - how to define a custom context name for a web application deployed in Tomcat. For example, if you are deploying a war named MyApp and want it to be available at http://localhost:8080/HelloWorld instead of http://localhost:8080/MyApp, then you'll have to configure a context name for that war. Here are some of the previous discussions which explain, how to do this:
You are requesting a page or servlet that's not there. Check whether you are referring to an incorrect file location or have made a typo in a URL. Calling an external resource while on a computer that has no access to the Internet can also cause this.
Is it possible to embed Tomcat in a desktop application, so it can be used without having to be installed as a separate server ?
Yes, that's possible. You can download a special embedding version of Tomcat, which is smaller than the standard distribution, but the normal version will do as well. All the details can be found in this article.
Update: Some of the Tomcat APIs have changed since that article was written; see this writeup for an example that works with Tomcat 7 and (presumably) newer.
How do I enable the EL (Expression Language) for Tomcat 5?
In order for Tomcat 5 to automatically enable the Expression Language in your JSP pages, your app must be declared as a Servlets 2.4 web application in the application's web.xml deployment descriptor.
How can I control a Tomcat server on a remote machine, e.g. to restart a web app or Tomcat itself?
Tomcat comes with a number of Ant tasks that can be used to control it from afar. Some documentation about that is here.
ProxyApacheHttpdAndTomcat Tomcat crashes with a 'java.lang.OutOfMemoryError: PermGen space' message. What gives?