  We propose the use of Soft Constraints as a natural way to model Service
Oriented Architecture. In the framework, constraints are used to model
components and connectors and constraint aggregation is used to represent their
interactions. The "quality of a service" is measured and considered when
performing queries to service providers. Some examples consist in the levels of
cost, performance and availability required by clients. In our framework, the
QoS scores are represented by the softness level of the constraint and the
measure of complex (web) services is computed by combining the levels of the
components.
