How to enable logging usage data in Open DACS API?

To enable logging usage data to log login and permission check
events of the users, please follow the steps below:

1. DACS has to enable what
   type of usage logging can be logged on DACS UI/Console at Tools -> Usage -> Set
   Usage Logging Filters… and select Eventsto log as example shown below that enables to log all events:

2. The Open DACS application specifies
the preference usage logging(com.reuters.rfa.dacs.AuthorizationUsageType class) which can be:

• DONT_PERFORM_USAGE_LOGGING - usage logging
  should not be performed
• ALWAYS_PERFORM_USAGE_LOGGING - usage logging
  should be performed
• ONLY_SUCCESS_PERFORM_USAGE_LOGGING
  - usage logging should be performed for the specified
  Authorization operation only if the operation produced an access success.
• ONLY_DENIAL_PERFORM_USAGE_LOGGING - usage logging
  should be performed for the specified Authorization operation only if the
  operation produced an access denial.

When it logs in and
checks authorization subscription. For example:

// All operations of usage logging performed.
AuthorizationUsageType usage = AuthorizationUsageType.ALWAYS_PERFORM_USAGE_LOGGING; 
// Encapsulate the principal instance in the AuthorizationRequest instance.
AuthorizationRequest request = new AuthorizationRequest();
// Set usage logging filter when log-in event occurs.
request.setUsageLogging(usage);
..
// Check subscription of item with the DACS server.
authCheckResult = _agent.checkSubscription(_handle, usage,_reqtype,authCheckStatus,_serviceName, itemName, lockData);

3. Make the OpenDACS application
waits for the usage is logged. Since the usage
will be logged periodically around 5 seconds and it will not be logged after AuthorizationSystem.release(), the application
should wait for the usage is logged before AuthorizationSystem.release() is called,
for example:

try 
{
//sleep 10 second to wait for usage is logged 
//before releasing AuthorizationSystem
        Thread.sleep(10000);
}catch(Exception e) {
        e.printStackTrace();
}
//closing the connection from the dacs sink daemon. 
//The method destroys AuthorizationAgent, releases AuthorizationSystem and destroys EventQueue.
client.closeDaemonConnection(true);

4.Disable Rendezvous transport
in dacs.env. DACS sink daemon with Rendezvous-enabled
flushes its cache of usage data to DACS infrastructure. Hence, usage data is
not written in the usage file. Please make sure that all DACS_RV parameters do not exist or are commented. The example of dacs.env:

#DACS_RV_PROTO="TRUE,7999,;224.1.1.5,tcp:192.168.27.52:7500"; export DACS_RV_PROTO
#DACS_RV_SENDRATE="3,15,30,63,123,243,-"; export DACS_RV_SENDRATE
#DACS_RV_USAGE_SIZE="4194304"; export DACS_RV_USAGE_SIZE
#DACS_RV_USAGE_AGE="1440"; export DACS_RV_USAGE_AGE