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Tomcat as we all know is a Web Container available with Apache family of products. It implements Java Servlet 2.5 API and Java Server Pages 2.1 API. Apache Geronimo which is a Java EE5 certified application server which Apache Derby, Apache Active MQ, Apache AXIS, Apache Tomcat etc pre-integrated. As a result while working with Geronimo you will be working with same Tomcat engine as the standalone version of Tomcat. However there are some differences which we will discuss in upcoming sections

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Implementation Analysis

While working with Geronimo you will be working with same Tomcat as the standalone Tomcat. This section will enlist the basic differences/similarities between Geronimo and Tomcat

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In order to overcome most migration related issues you need to figure out how each service is mapped within Tomcat and apply to Community EditionApache Geronimo. We will enlist some scenarios in this regard

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In case you are unwilling to remove jars from your current environment. May be you want to use your version of jars and geronimo ships a very different version of jars. In that case also geronimo provides an easy configuration. You can configure geronimo-web.xml to add <inverse-classloading/> tag. Using this tag the classloading hierarchy will change to Child First.

JSP Reloading

If you have configured Tomcat for JSP reloading than you would want to have the same in geronimo. This can be easily achieved in geronimo by editing <geronimo_home>/var/catalina/conf/web.xml.

Search for <servlet-class>org.apache.jasper.servlet.JspServlet </servlet-class> and add the following elements under the servlet class

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modificationTestInterval is time in seconds.

Persist JSP Compilation

If your Tomcat server is configured to persist JSP compilation between server restarts than you can configure geronimo as well for the same configuration. However there are two ways you can configure this in geronimo.

Server scoped

Using this you can retain the compiled JSPs of all Web applications running in the server across server restarts. Edit <geronimo_home>/var/catalina/conf/web.xml. Search for org.apache.jasper.servlet.JspServlet and add the following elements

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Create a directory <geronimo_home>/var/catalina/temp. All the web applications will be compiled and stored in temp directory. These will persist over server restarts.

Application scoped

Configure the web deployment descriptor web.xml in application as follows

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You need to create the temp directory in this case as well.

References

Following resources can be useful while migrating from Tomcat to Geronimo
1) http://geronimo.apache.org/schemas-2.1/docs/geronimo-module-1.2.xsd.html - ^{Image Removed} Look for inverse-classloading. You may also want to know more on dependencies, hidden-classes, non-overridable-classes. These all elements will be helpful in modifying the geronimo-web.xml.
2) Learn how to configure JMS with apache geronimo - http://cwiki.apache.org/GMOxDOC21/web-application-for-jms-access.html^{Image Removed}
3) Learn how to configure JDBC with apache geronimo- http://cwiki.apache.org/GMOxDOC21/web-application-for-jdbc-access.html^{Image Removed}
4) For security related configurations you can refer- http://cwiki.apache.org/GMOxDOC21/configuring-security.html^{Image Removed}
5) More on configuring various services- JMS, JDBC http://cwiki.apache.org/GMOxDOC21/configuring-services.html^{Image Removed}