We present an architecture to define and maintain Service Level Agreements, which was developed as part of a larger project, Oceano. An XML Contract is used to establishes an SLA between a customer and a service provider. This contract includes report definition, violation policy descriptions, penalties for disruption of service and pricing. The information provided in the contract must be validated for integrity, to avoid conflicts and errors. In addition, we need to guarantee that the provider has a sufficient number of resources to support the defined service level. Oceano will monitor the enforcement of the contract and triggers the policy engine whenever a violation occurs. Contract Violations are expressed as policies, which include a violation scenario, start and stop time, the violator agent and a related action. The possible actions are procedures to correct the problem, and/or apply monetary value to be charged from the service provider violator. A pricing engine (that combines the aggregate cost values of each resource involved in the violation scenario) is responsible for the billing calculations. Reports are periodically generated to inform the participants of the system behavior. We address the problem of SLA definition by using customer feedback and providing a flexible way to define and monitor the quality of service. Another important issue is the integration between the SLA monitoring and pricing model. We will present recent results, and ongoing work.