A Framework for the Management of Operator Policies and User Preferences for Service Compositions in the IP Multimedia Subsystem

The IP Multimedia Subsystem (IMS) is a telecommunication middleware platform with robust service features that enables the delivery of a wide range of services to mobile network subscribers. Network operators are encouraged to develop services from service building blocks in order to avoid redundancies by re-using existing functionality. In this environment, operators must be able to control the service execution chain in order to prevent undesirable interactions from occurring between individual building blocks. It is also in their interests to provide subscribers with personalisation options so that they can modify service compositions and define their own preferences for how they would like their services to behave during live sessions. This paper describes a solution for these challenges that involves the storage of service information in an XDMS and allows operator staff and subscribers to manage this information using the XCAP protocol. The ETSI-defined XCAP application usage named simservs was chosen to demonstrate an application usage that can be used to create service compositions in XML format. A prototype is described that uses components of the open source Mobicents project to verify the suitability of the design. This work is part of a larger effort aimed at modeling interaction management in the IMS through the use of a service broker that is part of an extended IMS service layer (EISL). The service broker´s functional and structural architecture have not yet been standardised.