code: public void setJmsAcknowledgeMode(int mode){
  		switch (mode) {
  		case Session.AUTO_ACKNOWLEDGE:
  		case Session.CLIENT_ACKNOWLEDGE:
  		case Session.DUPS_OK_ACKNOWLEDGE:
  			break;
  		default:
  			throw new IllegalArgumentException("Unknown Acknowledge mode: " + mode + " (See javax.jms.Session for valid values)");
  
  		}
  		this.jmsAcknowledgeMode = mode;
  	}
docs: Sets the JMS Session acknowledgement mode for the JMS seesion associated with this spout.
  <p/>
  Possible values:
  <ul>
  <li>javax.jms.Session.AUTO_ACKNOWLEDGE</li>
  <li>javax.jms.Session.CLIENT_ACKNOWLEDGE</li>
  <li>javax.jms.Session.DUPS_OK_ACKNOWLEDGE</li>
  </ul>
  @param mode JMS Session Acknowledgement mode
  @throws IllegalArgumentException if the mode is not recognized.