Translations of Service Level Agreement in Systems Based on Service Oriented Architecture

The gain of the paper is to introduce and to discuss a formal specification of computer system’s Service Level Agreement (SLA) and its translation into structure of complex services (composed of atomic services) delivering required functionalities and non-functionalities in distributed environment. The SLA is composed of two parts specifying quantitative and qualitative requirements. The former requirements define structure of the adequate complex services as a directed graph, where potential parallelism of atomic services performance may be taken into account. The qualitative requirements are applied to select the optimal complex service realization scenario; it is based on assumption that various atomic services distinguished in the complex services structure are available in the environment in different versions and locations. Different versions of atomic services are delivering the required functionalities and satisfy non-functionalities at various levels. Various locations of atomic services means that the time and cost of atomic services delivery (communication and calculation) may vary. Proposed model of SLA translation into complex services causes that a scenario variants may be applied — among others — to calculate upper and lower complex services’ delivering times and to estimate validity of possible parallelism in complex services.