Ro online charging Web service provides an IMS™ Application Server application with a Diameter messaging interface to enable the application to send credit control messages to online charging servers. The IMS Application Server application is referred to as a client of the Web service application.
The Ro online charging Web service also provides subscription and notification operations for an IMS Application Server to subscribe to receive notifications when the Charging Trigger Function (CTF) (the IMS Application Server application) must reauthenticate with the Online Charging System (OCS) or when a reauthorization subscription expires.
The choice of using session charging versus event charging will depend on the applications using this interface. The actual accounting functionality is based on other network elements, such as billing, and is not part of the Ro online charging Web service. The Ro interface defines several high level Web service methods used for online charging including sendCCInitial(), sendCCUpdate(), and sendCCTermination() for session handling and event charging with unit reservation. The sendCCDirectDebit(), sendCCRefund(), and getCCServicePriceEnquiry() are used for event charging without unit reservation. And, the subscribeCCReAuth(), unsubscribeCCReAuth, and notifyCCReAuth() are used for subscribe and notify requests. The notify request (notifyCCReAuth()) is sent as a Web service request from the Diameter Enabler to the Application.
If the Diameter Enabler Web service supports notifications, the IMS Application Server application must use the WSDL and/or helper classes to implement the client Web service that receives notifications. The URL of the client Web service is provided to the Diameter Enabler Web service through the subscribeCCReAuth() request.
The Diameter Enabler is also capable of receiving notifications requests from a Diameter Server. The Diameter Enabler validates the contents of the Diameter request packet and responds to the peer with a Diameter answer packet. If the IMS Application Server Application has created a subscription to receive the notifications, the Diameter Enabler opens an outbound Web service request to a Web service endpoint provided in the subscription data, and passes the reauthorization notification information accordingly.