For example the following code conf/server.xml is for oracle connection
to DB2 you have to modify the string url
<Context
path="/mywebapp"
reloadable="true"
docBase="C:\home\akobashikawa\work\myeclipse\ssc\WebRoot"
workDir="C:\home\akobashikawa\work\myeclipse\ssc\work">
<Logger className="org.apache.catalina.logger.SystemOutLogger"
verbosity="4" timestamp="true"/>
<Resource
name="jdbc/oracleTest"
auth="Container"
type="javax.sql.DataSource"
maxActive="20"
maxIdle="10"
maxWait="-1"
username="usuario"
password="secreto"
driverClassName="oracle.jdbc.OracleDriver"
url="jdbc:oracle:thin:@mydbserver.acme.com:1521:mydb"
/>
</Context>
good luck
