Trusted Components. or Contract-Compliant Components. Kung-Kiu Lau University of Manchester, UK

Transcription

1 Trusted Components or Contract-Compliant Components Kung-Kiu Lau University of Manchester, UK

2 Overview Trusted Components Initiative CoLogNET: NoE in Computational Logic Trusted Components, or Contract-Compliant Components ng-kiu Lau, University of Manchester CBSEnet Workshop 03 1

3 The Trusted Components Initiative Original paper: Trusted Components for the Software Industry Bertrand Meyer, ISE Inc and Monash University (now at ETH, Zurich) Christine Mingins, Monash University Heinz Schmidt, Monash University ng-kiu Lau, University of Manchester CBSEnet Workshop 03 2

4 The Trusted Components Initiative (Continued) Aim: To provide a solid foundation for the software industry through extensive libraries of trusted reusable software components. Objective: To build trust from a combination of: Design by Contract; mathematical proofs of correctness; testing; wide public scrutiny; evaluation through metrics; exhaustive validation in practical projects; rigorous change management. ng-kiu Lau, University of Manchester CBSEnet Workshop 03 3

5 Workshop on Trusted Components 8-11 January 2003, Prato, Italy Talks: K.-K. Lau, Some Ingredients of Trusted Components L. F. Andrade, J. L. Fiadeiro, Trust: Components vs Services M. Huisman, Secure Smartcards: A component-based view Matsumoto et al., A Lightweight Formal Method for Component-Based Software using Equational Specifications M. Barnett, W. Schulte, Trust through Test J. Malenfant et al., Contract Spaces for Trusted Components N. Tran et al., Common Runtime Support for Assertions D. Deveaux, The Design for Trustability Approach K. Arnout, Extracting Implicit Contracts from.net Assemblies J. Kiniry, E. Poll, Opportunities and challenges for formal specification of Java programs ng-kiu Lau, University of Manchester CBSEnet Workshop 03 4

6 Workshop on Trusted Components (Continued) Tutorials: Bertrand Meyer, Towards a Component Quality Model Rustan Leino, Static checking module by module Kokichi Futatsugi, CafeOBJ Bertrand Meyer, Techniques for Proving Classes Panel Discussions: Specifying legal parameter values (moderator: Rustan Leino) Defining and Achieving Component Quality (moderator: Bertrand Meyer) Challenges and Perspectives for Trusted Components (moderator: Bertrand Meyer) Motto : Resolve Formal Methods and Reuse ng-kiu Lau, University of Manchester CBSEnet Workshop 03 5

7 CoLogNET: NoE in Computational Logic Workpackage on Component-based Software Development (CBD) Leader: Kung-Kiu Lau Aim: To promote the use of Computational Logic in CBD research in both industry and academia. CoLogNET CBD Workshop, Madrid, September CoLogNET-sponsored Workshop on Formal Aspects of Component Software, Pisa, September Joint CoLogNET-CBSEnet workshop, 2004? ng-kiu Lau, University of Manchester CBSEnet Workshop 03 6

8 Trusted Components Software components must be trustworthy no incentive to deploy them otherwise Trustworthiness = Contract Compliance + How When Where ng-kiu Lau, University of Manchester CBSEnet Workshop 03 7

9 Contract-Compliant Components required services contract software component provided services ng-kiu Lau, University of Manchester CBSEnet Workshop 03 8

10 Component and Contract Specification Name CONTEXT( Signature: Axioms: Constraints: ; ; ; ) Provided services Required services INTERFACE Operations: Dependencies: specifications; op1( constraints; ), op2( ), ; ; Contracts CODE Code for op1, op2, (Cf. Szyperski s definition) ng-kiu Lau, University of Manchester CBSEnet Workshop 03 9

11 CBD: A Paradigm Shift in Reasoning CBD represents a paradigm shift in software engineering Contract compliance (in all compatible contexts) should be guaranteed a priori Trust is, by definition, a priori ng-kiu Lau, University of Manchester CBSEnet Workshop 03 10

12 Predictable Assembly contract A contract compliant component A + contract B contract compliant component B? contract C? contract compliant component C ng-kiu Lau, University of Manchester CBSEnet Workshop 03 11

13 A Priori (Compositional) Reasoning Assembly prediction: A B C Interface Interface? + Code Code? Component A Component B Component C Component certification: A Interface Code + B Interface Code C Interface? Code? A Certified Component B Component C component A ng-kiu Lau, University of Manchester CBSEnet Workshop 03 12

14 A Priori (Compositional) Reasoning (Continued) Predictable assembly: A Interface Code Certified component A B + Interface Code Certified component B C Interface Code Certified component C ng-kiu Lau, University of Manchester CBSEnet Workshop 03 13

15 A Spiral Model for CBD Requirements Spec design Architectural Spec Top down Library of contract compliant components Spec (predictable) assembly Correct software yes Correct software? (predictable) assembly no verification & customisation Library of contract compliant components Bottom up ng-kiu Lau, University of Manchester CBSEnet Workshop 03 14

16 Conclusion CBD is a paradigm shift Trust in components should be established a priori Trusted Components = Contract-Compliant Components Prove once, reuse often ng-kiu Lau, University of Manchester CBSEnet Workshop 03 15