public List<Conversation> getConversationList( int person_id, int page_size, int offset ){
		if( !handler_cvs.initialize() || !handler_msg.initialize() 
				|| !handler_person.initialize() || !handler_group.initialize() ){
			System.out.println( "ConversationServer : failed to initialize!" );
			return null;
		}
		
		List<Conversation> list = handler_cvs.getConversationList( person_id, page_size, offset );
		if( list == null || list.size() <= 0 ){
			closeAll();
			return null;
		}
		for( int i = 0; i < list.size(); i ++ ){
			if( !getConversationInfo( list.get(i) ) ){
				System.out.println( "ConversationServer : failed to get conversation " + list.get(i).cvs_id );
			}
		}
		closeAll();
		return list;
	}