Towards Specification and Refinement of Contracts with Environment Changes

The web environment creates risks together with benefits for web services. Web services often engage attacks from hackers or anyone having hostile intensions. The behavior of services is often effected by the environment changes which should be included in its specifications. In addition, services usually have some mechanisms provided by the developers to deal with the environment changes, especially attacks. However, common specifications of services seldom contain such information. This paper provides a formal behavioral model based on the service behaviors related to its environments and environment changes. A refinement relation is also provided in the behavior model. This model can form a view to analyze the environment influence to the service and compare them according to their defending mechanisms.