active mq broker start up issue.

["Suchitha Koneru (sukoneru)" <su...@cisco.com>]

Hello Active MQ users , 
 
We use Tomcat server 5.5.20 with two web applications , namely Webapp A
and Web App. B.
The inter web app communication is via the active mq broker.  The active
mq version is 4..0.2 . 
As of now, the web app A is always started before B. Hence the broker is
specified as a Servlet Context Listener in web.xml of the web app A.
The problem we have  is to start the broker irrespective of the order of
initialization of  web apps .
  We would be adding a new web app called Webapp C . In this scenario, I
will not have a control on the order in which the web apps are
initialized by Tomcat. The code to start the broker , takes into
account, that if the broker port is already occupied, it will  attempt
to start the broker at a randomly generated  port for 5 times.
 
 Tomcat does not give us the flexibility of starting the web apps in
particular order.  The web.xml of Webapp A is as follows 
 
<!-- starting active mq broker -->

<listener>

<listener-class>com.messaging.ActiveMQBrokerStartListener</listener-clas
s>

</listener>

<!-- starting the rest of services in web app   A -->

<listener>

<listener-class>

com.context.ApplicationInitListener

</listener-class>

</listener>

 

// code for ActiveMQBrokerStartListener

BrokerService broker = new BrokerService();

int counter = 0;

Properties activeMQProperties = new Properties() ;

 

int portNum ;

public void contextInitialized(ServletContextEvent arg0) {

System.out.println("Starting ActiveMQ Broker Service...");

//for the broker URI , do not have leading or trailing spaces

File dir = new File("../../activemq");

Logger logger = Logger.getLogger(ActiveMQBrokerStartListener.class);

dir.mkdir();

InetAddress ipAdress ;

broker.setDataDirectory(dir);

try{

ipAdress = InetAddress.getLocalHost();

}catch(UnknownHostException e){

logger.error("error in obtaining Local Host address "+e.getMessage());

return ;

}

// getting the port number from the active mq properties file

try{

activeMQProperties.load(new
FileInputStream(MessagingConstants.ACTIVEMQ_PORT_FILE_PATH ));

portNum =
Integer.parseInt(activeMQProperties.getProperty(MessagingConstants.Activ
eMQPort,"-1"));

if(portNum == -1){

logger.error("active mq port not configured via the proeprties file
using the default port value as
"+MessagingConstants.DEFAULT_PORT_VALUE);

portNum = MessagingConstants.DEFAULT_PORT_VALUE ;

}

}catch(Exception e){

logger.error("exception while getting port properties "+e.getMessage());

}

while(counter < 5){ // 5 attempts to start the broker 

try{ 

// broker url is
tcp://171.69.155.137:61716?trace=true&wireFormat.maxInactivityDuration=-
1

broker.addConnector(MessagingConstants.CONNECTOR+
ipAdress.getHostAddress()+":"+portNum+MessagingConstants.ACTIVEMQ_URL_SU
FFIX);

broker.start();

logger.info("Active MQ Broker Started at local host port "+ portNum);

break;

}catch(Exception e){

// System.out.println(e.getMessage());

if(e instanceof java.net.BindException){ //broker port is already
occupied by another process, try to start the broker at different 

// port number

portNum = getRandomPortNumber() ;

logger.info("trying to start the broker at port "+portNum);

counter ++;

}else{

logger.error("exception while starting broker : ",e);

e.printStackTrace();

}

}

}

Please let me know, if there is a way to ensure that the broker is
started first , irrespective of the order of initilization of web apps.
I'll also do a  google search on this issue.

thanks,

Suchitha.