Wednesday, October 31, 2007

Datasources, Tomcat and Netbeans

I am currently developing a JSF application using NetBeans 6.0 and Tomcat 6.0.14. When I tried to deploy the application on our production server (by just dumping the .war file in Tomcat's webapps directory, it didn't work properly. I could access the app's start page, but it failed to render the following pages.

A look in tomcat's log files revealed that there was a problem with the mysql driver.

Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver

I tried to make sure that the mysql-connector jar is included in the project's imported libraries and that it can be found in META-INF/lib, but this didn't help. I later found out that in Netbeans, under Tools→Servers→Deployment there is a "Enable JDBC driver deployment option". Disabling this resulted in a replication of the problem on my development machine, even when using NetBeans. So I had to find out what it was that NetBeans was doing when this option was enabled and repeat it on the production server.

I started making a research on the net, based on the error message I was getting. The oslution proposed by most people was to place the mysql driver jar in tomcat's common/lib directory and nowhere else, but this just wouldn't do the trick for me. I also checked that the datasource's declarations in the web.xml and context.xml files were correct.

A final attempt to go through the steps to create and declare a datasource as described in tomcat's website revealed a small detail in step 1: the driver jar file needs to be placed in the $CATALINA_HOME/lib directory rather than $CATALINA_HOME/common/lib.

Still remains to check whether there is a difference in the directory structure in versions 5.5 and 6.0 of tomcat, since no common directory appears to exist in installations of tomcat 6.0.