Service Oriented Architecture (SOA) enables cooperation in an open and highly concurrent context. In this paper, we investigate the management of personal information by an SOA service consumer while invoking composed services, where we will study the balance between quality of service (that works better when provided with our personal data) and the consumer’s data access policy.We present a service architecture that is based on an open epistemic multi-agent. We describe a logic-based trust module that a service consumer can use to assess and explain his trust toward composed services (which are perceived as composed actions executed by a group of agents in the system).We then illustrate our solution in a case study involving a professional social network.