Reconciling Trust and Modularity Goals in Web Services by Hridesh Rajan, Jia Tao, Steve Shaner, and Gary T. Leavens Abstract Web services are distributed software components, that are decoupled from each other using interfaces with specified functional behaviors. However, such behavioral specifications are insufficient to demonstrate compliance with certain temporal non-functional policies. We show an example demonstrating that a patient's health-related query sent to a health care service is answered only by a doctor (and not by a secretary). Demonstrating compliance with such policies is important for satisfying governmental privacy regulations. It is often necessary to expose the internals of the web service implementation for demonstrating such compliance, which may compromise modularity. In this work, we provide a language design that enables such demonstrations, while hiding majority of the service's source code. The key idea is to use greybox specifications to allow service providers to selectively hide and expose parts of their implementation. The overall problem of showing compliance is then reduced to two subproblems: whether the desired properties are satisfied by the service's greybox specification, and whether this greybox specification is satisfied by the service's implementation. We specify policies using LTL and solve the first problem by model checking. We solve the second problem by refinement techniques. Keywords: web services, data integrity, greybox specification, refinement 2006 CR Categories: D.3.1 [Programming Languages] Formal definitions and theory - syntax and semantics F.3.1 [Logics and meaning of programs] Specifying and reasoning about programs - assertion, mechanical verification, pre and postcondition This technical report can be cited as: @Techreport{Rajan-Tao-Shaner-Leavens-08, author = {Hridesh Rajan and Jia Tao and Steve M. Shaner and Gary T. Leavens}, title = {Reconciling Trust and Modularity in Web Services}, institution = {Department of Computer Science, Iowa State University}, year = {2008}, number = {08-07}, month = {July}, URL = {ftp://ftp.cs.iastate.edu/pub/techreports/TR08-07/TR.pdf}, Annote = {51 references} } Copyright (c) 2008, Hridesh Rajan, Jia Tao, Steve Shaner, and Gary T. Leavens.