|This paper describes a Service Creation approach being developed
in the EU funded ACTS TOSCA (TINA Open Service Creation Architecture) project
to rapidly develop validated TINA based multimedia telecommunications services.
The approach is based around object-oriented software frameworks in SDL
which are specialised towards services by means of graphical paradigm tools.
Further, in TOSCA, the need for service interworking across service provider domains via federation has been recognised in order to allow users to join service sessions offered by providers they are not customers of. However, service interworking may cause undesired behaviour - the so called service interaction phenomenon. This paper focuses on this issue and the underlying technology of the service creation approach with emphasis on how service federation has been implemented.