Abstract
The concept of situation proposed in Situ, a context aware service-centric model, is the instant status of a software system environment, including context values and user's actions, as well as the predicated user's desires, which are critical for service evolution because they usually reflect user's requirements on the system. For better applying the situation theory in practice, it is essential to provide formal specification and explicit description for situations. In this paper, we present a situation-centric specification language -- SiSL, which formalizes the situation-theoretic approach to humanintention-driven service evolution proposed in Situ using second order logic. SiSL classifies the entities and their relations that are used to reason about user's behaviors in the software system domains, and it supports formal description of situations and intentions. SiSL provides a set of axioms which establish a theoretical framework for inferring pre-defined use's desires and detecting new desires based on observations of user's actions and context values. A case study of paper submission and review system - PaperSR - is used to explain the concepts and ontology of SiSL.