This is how JNI is used.Create .h file,then .c/.cpp file and create .dll using visual stdio

http://electrofriends.com/articles/jni/jni-part1-java-native-interface/

use of observer interface and observable class

http://www.coderanch.com/t/380786/java/java/Observable-class-Observer-interface

link to configuring jdbc.properties for different DB's

https://src.springframework.org/svn/spring-samples/petclinic/trunk/src/main/resources/jdbc.properties

configure a dataSource in tomcat server

This is the dataSouce bean:
<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
      <property name="jndiName" value="java:comp/env/ig/jdbc/rtfdatasource"/>
      <property name="resourceRef" value="true" />
     </bean>

change the context.xml file which looks like:

<Loader loaderClass="org.springframework.instrument.classloading.tomcat.TomcatInstrumentableClassLoader" />

<Resource name="ig/jdbc/rtfdatasource" auth="Container" type="javax.sql.DataSource" username="rtf_uat" password="************" driverClassName="oracle.jdbc.OracleDriver"
             url="jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=vrdevora003.iggroup.local)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=RTF.DEV.IGGROUP.LOCAL)))" maxActive="20" maxIdle="2" minIdle="1" initialSize="2" />