One of the current challenges of Service Oriented Engineering is to provide instruments for dealing with dynamic and unpredictable user requirements and environment. Traditional approaches based on workflow for orchestrating services provide little support for configuring at run-time the flow of activities.This paper presents a general approach for composing and orchestrating services in a self-organization fashion. User requirements are made explicit in the system by a goal specification language. These can be injected into the running orchestration system that is able to autonomously and contextually reason on them. Therefore, the system dynamically organizes its structure for addressing the result. A prototype of the system has been implemented in JASON, a language for programming multi agent systems. Some aggregate statistics of execution are reported and discussed.