Applications can examine the Result-Code AVP in CCA error responses from the OCF to detect the cause of a failure and take an appropriate action. Locally-generated errors, such as an unavailable peer or invalid route specification, cause the request send method to throw an IOException to with a detailed message indicating the nature of the failure.

Applications can also use the Diameter Timer Tx value for determining when the OCF fails to respond to a credit authorization request. Timer Tx has a default value of 10 seconds, but can be overridden using the tx.timer init parameter in the RoApplication configuration. Timer Tx starts when a CCR is sent to the OCF. The timer resets after the corresponding CCA is received.

If Tx expires before a corresponding CCA arrives, any call to waitForAnswer immediately returns null to indicate that the request has timed out. An application can then take action according to the value of the Credit-Control-Failure-Handling (CCFH) AVP in the request. See section 5.7, "Failure Procedures" in RFC 4006 (http://www.ietf.org/rfc/rfc4006.txt) for more details.

Example 4-7 terminates the credit control session if timer Tx expires before receiving the CCA. If the CCA is received later by the Diameter subsystem, the message is ignored because the session no longer exists.

CCR ccr = session.createCCR(RequestType.INITIAL);
ccr.setCreditControlFailureHandling(RequestType.TERMINATION);
ccr.send();
CCA cca = ccr.waitForAnswer();
if (cca == null) {
  session.terminate();
}