BackGround: For webapps properties are stored in the WEB-INF/web.xml but this xml contains a lot more than just properties and can be a bit cumbersome to edit by hand. These properties are known as JNDI environment entries. Typically servlet containers will have a special GUI for changing these properties and this is what is advised for you to use. Tomcat GUI by default is no longer installed with tomcat 5.5 and the GUI is not known to be reliable.
Tomcat will also allow 'you' to place a special xml properties file in the {tomcat}/conf/Catalina/localhost named {context}.xml.
Click on the below link to take you to the property editor page which will write the properties in the conf/Catalina/localhost.
Click on this link (advise open in a new window) here to edit JNDI properties.

Changing Properties First we need to change some properties in the environment entries. Click on the above link if you haven't already to change properties.

Setting up for data
Advise to click on the Fingerprint page to confirm properties are changed. (might want to open in a new tab/window so you can still read docs).