How is "acknowledge" used? - spring-integration

Question

I am trying to integrate my application with JMS Queues (using ActiveMQ).
My requirement is, that once the message has been read from the input queue, message should not be removed from the queue. Rather I want to send an acknowledgement that application has received that message.
I am not able to understand the exact usage of property "acknowledge".
My code is as below:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:int-jms="http://www.springframework.org/schema/integration/jms"
xmlns:jms="http://www.springframework.org/schema/jms"
xmlns:int="http://www.springframework.org/schema/integration"
xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
http://www.springframework.org/schema/jms http://www.springframework.org/schema/jms/spring-jms.xsd
http://www.springframework.org/schema/integration/jms http://www.springframework.org/schema/integration/jms/spring-integration-jms.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!-- Component scan to find all Spring components -->
<context:component-scan base-package="com.poc.springinteg._7" />
<!-- -->
<bean id="remoteJndiTemplate" class="org.springframework.jndi.JndiTemplate" lazy-init="false">
<property name="environment">
<props>
<prop key="java.naming.provider.url">tcp://localhost:61616</prop>
<prop key="java.naming.factory.url.pkgs">org.apache.activemq.jndi</prop>
<prop key="java.naming.factory.initial">org.apache.activemq.jndi.ActiveMQInitialContextFactory</prop>
<prop key="connectionFactoryNames">DefaultActiveMQConnectionFactory,QueueConnectionFactory</prop>
<prop key="queue.SendReceiveQueue">org.apache.geronimo.configs/activemq-ra/JCAAdminObject/SendReceiveQueue</prop>
<prop key="queue.SendQueue">org.apache.geronimo.configs/activemq-ra/JCAAdminObject/MDBTransferBeanOutQueue</prop>
</props>
</property>
</bean>
<bean id="remoteConnectionFactory" class="org.springframework.jndi.JndiObjectFactoryBean" lazy-init="false">
<property name="jndiTemplate" ref="remoteJndiTemplate"/>
<property name="jndiName" value="QueueConnectionFactory"/>
<property name="lookupOnStartup" value="true" />
<property name="proxyInterface" value="javax.jms.ConnectionFactory" />
</bean>
<!-- writing queue -->
<bean id="destinationqueue"
class="org.apache.activemq.command.ActiveMQQueue">
<constructor-arg index="0">
<value>OutputQueue_7</value>
</constructor-arg>
</bean>
<int:channel id="outbound"/>
<int-jms:outbound-channel-adapter id="jmsOut"
channel="outbound"
connection-factory="remoteConnectionFactory"
destination="destinationqueue" />
<!-- reading queue -->
<bean id="sourceQueue" class="org.apache.activemq.command.ActiveMQQueue">
<constructor-arg index="0">
<value>OutputQueue_7</value>
</constructor-arg>
</bean>
<bean id="messageListenerContainer"
class="org.springframework.jms.listener.DefaultMessageListenerContainer">
<property name="connectionFactory" ref="remoteConnectionFactory"/>
<property name="destination" ref="sourceQueue"/>
<property name="maxConcurrentConsumers" value="10"/>
<property name="concurrentConsumers" value="1"/>
<property name="autoStartup" value="true"/>
</bean>
<int:channel id="inbound"/>
<int-jms:message-driven-channel-adapter id="jmsIn"
channel="inbound"
extract-payload="false"
container="messageListenerContainer" />
<int:service-activator input-channel="inbound"
output-channel="outbound"
ref="messageReader"
method="onMessage" />
</beans>
-- Message Reader Class
import javax.jms.JMSException;
import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.messaging.Message;
import org.springframework.stereotype.Component;
#Component("messageReader")
public class MessageReader
{
#ServiceActivator
public void onMessage(Message inboundMessage) {
System.out.println(" -------Message Read Start--------");
System.out.println(inboundMessage.getHeaders());
System.out.println(" -------Message Headers Reading completed--------");
System.out.println("payload-->" + inboundMessage.getPayload().getClass());
String payload = inboundMessage.getPayload().toString();
System.out.println("payload value-->" + payload);
org.apache.activemq.command.ActiveMQTextMessage obj = (org.apache.activemq.command.ActiveMQTextMessage)inboundMessage.getPayload();
System.out.println("Object-->" + obj);
String var = null;
try {
var = obj.getText();
System.out.println("Datastructure-->" + obj.getText());
} catch (JMSException e) {
e.printStackTrace();
}
}
}
---- Message Writer Class
#Component("sendMessage")
public class SendMessage {
#Autowired
private MessageChannel outbound;
public void send(String name)
{
Entity entity = new Entity(1,"anuj");
Message<Entity> message = MessageBuilder.withPayload(entity)
.setHeader("Message_Header1", "Message_Header1_Value")
.setHeader("Message_Header2", "Message_Header2_Value")
.build();
outbound.send(message);
}
}
-- Application main class
public class App {
public static void main( String[] args )
{
ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:7_applicationContext.xml" );
SendMessage sendMessage = (SendMessage)applicationContext.getBean( "sendMessage", SendMessage.class);
for(int i=0;i<10;i++){
sendMessage.send("This is Message Content");
}
applicationContext.registerShutdownHook();
}
}