Abstract: Trust calculation rely on communication and sharing of recommendatory trust information from so called third parties in the high dynamic,open,heterogeneous and distributed service computing environments．However current research methods in trust representation and calculation lack the analysis and reasoning on experience information,decreasing reliability of trust calculation which is being aggravated by subjective and objective difference of entities within such networks environments．This paper first introduce trust representation and calculation based on formal semantics,then proposed an experience ontology in which explicitly represents concepts and properties related to interactions experience,namely E-Ont．At last,trust calculus were defined on the basis of experience sharing．Compared with trust calculus based on rating and context-aware rating,our method enhance the reliability of trust calculation and beneficial selecting of trusted service provider in open,heterogeneous and distributed environments.

Key words: Ontology,Experience,Reasoning,Context,Trust degree