A Service Level Agreement (SLA) is the electronic equivalent of a real-life contract, which describes expectations from a service and governs its consumption. Ideally, a SLA provides certainty as regards customer experience and Quality of Service (QoS) received. For selfcontained, isolated services this type of certainty is relatively straightforward to achieve. However, for services that are composed by others, or that rely on others to execute, such functional dependencies imply similar non-functional ones. Therefore, SLAs offered by a service to its customers are in turn depending on other SLAs, which the same service establishes in its role as a customer of the services it relies upon. In this paper we explore this dependency between different SLAs, and formalize the problem of converting an agreement for a composed service into individual agreements for the services from which it is composed.
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