The SCA Assembly Model consists of a series of artifacts which define the configuration of an SCA system in terms of service components which implement and/or use services and the connections which describe how they are linked together. The assembly is defined in terms of a set of SCA composites, which define components and reference the implementation code that provide business function and which also describe services and references and the wires that link them.
This specification can be downloaded from the Open SOA Collaboration.