Reconciling Trust and Modularity Goals in Web Services

By: Hridesh Rajan, Jia Tao, Steve M. Shaner, and Gary T. Leavens

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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.

ACM Reference

Rajan, H. et al. 2009. Reconciling Trust and Modularity Goals in Web Services. Technical Report #08-07. Iowa State University and University of Central Florida.

BibTeX Reference

@techreport{rajan2009reconciling,
  title = {Reconciling Trust and Modularity Goals in Web Services},
  author = {Rajan, Hridesh and Tao, Jia and Shaner, Steve M and Leavens, Gary T},
  year = {2009},
  month = {March},
  institution = {Iowa State University and University of Central Florida},
  number = {08-07},
  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.
  }
}