A technique for controlling a service composition process for a composite service is described. The composite service involves at least one telecommunication session for a user for a telecommunication network. In a method realisation (400) of this technique, the following steps are performed on a service execution platform within an application layer: in a first step (402), a message relating to new or an existing telecommunication session is received from a session control layer. In a next step (404), a service compositor is contacted with respect to a composite service involving the telecommunication session to which the message pertains. Then, a first command is received from the service compositor (406), and the command is executed (408). Further, run-time information that becomes available in context with execution of the first command is determined (410) and transmitted to the service compositor (412).