Service levels, security, and trust

This chapter covers the scientific background for the Service Level Module of the Unified Service Description Language (USDL). In addition to general service level concepts, we expand on two specific service level fields: security and trust. For that end we first review the state of the art in service level modeling, then we explain the design of the Service Level Module and position it among the rest of USDL. For security, two possible perspectives, a high level business view and a low level engineering approach, are introduced. With regards to trust, USDL is suitable to specify how a service can be rated by its consumers and to ensure that ratings of competing services are comparable, and hence to determine trustworthiness. Additionally, we present a description of non-security-related elements that can be exploited for trust estimation.