A priori verification of web services with abduction
This presentation is the property of its rightful owner.
Sponsored Links
1 / 20

A-Priori Verification of Web Services with Abduction PowerPoint PPT Presentation


  • 57 Views
  • Uploaded on
  • Presentation posted in: General

A-Priori Verification of Web Services with Abduction. Marco Alberti 1 Federico Chesani 2 Marco Gavanelli 1 Evelina Lamma 1 Paola Mello 2 Marco Montali 2. 1 ENDIF, Università di Ferrara 2 DEIS, Università di Bologna. Motivation: Service Oriented Computing. Web services:

Download Presentation

A-Priori Verification of Web Services with Abduction

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


A priori verification of web services with abduction

A-Priori Verification of Web Services with Abduction

Marco Alberti1

Federico Chesani2

Marco Gavanelli1

Evelina Lamma1

Paola Mello2

Marco Montali2

1 ENDIF, Università di Ferrara

2 DEIS, Università di Bologna


Motivation service oriented computing

Motivation: Service Oriented Computing

  • Web services:

    • Defined by their behavioural interface

    • Simple stand-alone applications, or

    • Potential components of complex applications, by

  • Composition of web services:

    • As specified by a choreography

  • Will the web services comply to the choreography?

A-Priori Verification of Web Services with Abduction


Choreographies vs mas protocols

Choreographies vs. MAS protocols

  • Similarities (Baldoni et al., LNCS 3670):

    • Both define rules for collaboration among peers

    • Both express dependencies and constraints in interactions

    • Both abstract away from internals, focusing on interface

  • Wide literature on MAS protocol verification

  • Approach: apply MAS techniques to SOC verification

A-Priori Verification of Web Services with Abduction


In this talk the a l lows framework

In this talk: The AlLoWS framework

  • Abductive Logic Web-service Specification

  • Language to specify choreographies and web service interfaces (originally: interaction protocols and reactive agents), with an abductive semantics

  • Definition of conformance of a web service to a choreography

  • Abductive proof procedures to verify conformance

A-Priori Verification of Web Services with Abduction


Representation of interactions

Representation of interactions

Interaction as exchange of messages.

  • Messages format:

    • mx(Sender, Receiver, Content)

  • Events: actual message exchanges

    • H(Message[,Time])

  • Expectations: desired message exchanges

    • E(Event[,Time])

A-Priori Verification of Web Services with Abduction


Choreography specification

Choreography Specification

  • Abductive triple <KBchor,εchor,ICchor>

  • ε: abducible signatures (events H and expectations Echor)

  • Choreography Knowledge Base: logic program with expectations in clause bodies

  • Choreography Integrity Constraints: implications relating events and expectations

A-Priori Verification of Web Services with Abduction


Choreography example

Choreography example

KBchor

  • deadline(10).

    ICchor

  • H(m1(X,Y),T1) /\ deadline(Td)

    → Echor(m2(Y,X),T2) /\ T2< T1 + Td

    \/ Echor(m3(Y,X),T2) /\ T2< T1 + Td

A-Priori Verification of Web Services with Abduction


Web service specification

Web Service specification

  • Abductive triple <KBws,εws,ICws>

  • ε: abducible signatures (events H and expectations Ews)

  • Web service Knowledge Base: logic program with expectations in clause bodies

  • Web service Integrity Constraints: implications relating events and expectations

A-Priori Verification of Web Services with Abduction


Conformance

Conformance

  • Our idea of conformance: a web service will comply to a choreography,provided that its peers comply too.

  • Feeble conformance: all expected events happen.

  • Strong conformance: all happened events are expected.

A-Priori Verification of Web Services with Abduction


Possible interaction

Possible interaction

  • A pair (HAP, EXP) that, together with the KB, entails the following:

    • a Goal (usually defines a needed event)

    • The integrity constraints

    • The web service being discussed follows its own expectations about itself

    • The other peers follow the choreography expectations about themselves

A-Priori Verification of Web Services with Abduction


Feeble conformance

Feeble conformance

A possible history HAP is feeble conformant if there exists EXP that, together with joined KBs, entails:

  • A goal

  • The integrity constraints (ICchor U ICws)

  • Ews(X)  H(X)

  • Echor(X)  H(X)

  • <HAP,EXP> is a feeble conformant interaction if EXP is minimal w.r.t set inclusion

  • A web service is feeble conformant if all the possible histories are feeble conformant

  • A-Priori Verification of Web Services with Abduction


    Strong conformance

    Strong conformance

    A feeble conformant interaction <HAP,EXP> is also strong conformant if it entails the following:

    • H(mx(ws,R,C))  Echor(mx(ws,R,C))

    • H(mx(S,ws,C))  Ews(mx(S,ws,C))

      A web service is strong conformant if all possible histories are strong conformant.

    A-Priori Verification of Web Services with Abduction


    The s ciff abductive proof procedure

    The SCIFF abductive proof procedure

    • Derived from Fung and Kowalski’s IFF

      • Originally applied to compliance verification in MAS

    • Properties:

      • Termination for acyclic programs

      • Soundness

      • Completeness

    • Generative version: g-SCIFF (events are abducible)

      • Applied to verification of protocol properties

    A-Priori Verification of Web Services with Abduction


    Conformance verification

    Conformance verification

    SCIFF

    Feeble

    Conformance

    Are all

    events

    expected?

    g-SCIFF

    SCIFF

    /\

    Possible

    Interaction

    HAP,EXP

    SCIFF

    Is HAP

    feeble

    conformant?

    Strong

    Conformance

    A-Priori Verification of Web Services with Abduction


    Example more capabilities

    Example: more capabilities

    • Choreography

      • H(m1(ws,X,C))→Echor(m2(X,ws,D))

    • Web service

      • H(m1(ws,X,C)) →Ews(m2(X,ws,D)) \/ Ews(m3(X,ws,D))

    • Result: feeble and strong conformant

    A-Priori Verification of Web Services with Abduction


    Example missing capability

    Example: Missing Capability

    • Choreography

      • H(m1(ws,X,C)) → Echor(m2(X,ws,D)) \/ Echor(m3(X,ws,D))

    • Web service

      • H(m1(ws,X,C)) → Ews(m2(X,ws,D))

    • Result: not feeble conformant

    • Counterexample:

      HAP = {H(m1(ws,a,c)),H(m3(a,ws,d))}

    A-Priori Verification of Web Services with Abduction


    Example wrong reply

    Example: Wrong reply

    • Choreography

      • H(m1(X,ws,C)) → Ews(m2(ws,X,D)) \/ Ews(m3(ws,X,D))

    • Web service

      • H(m1(X,ws,C)) → Echor(m2(ws,X,D))

    • Result: non conformant

    • Counterexample

      HAP = {H(m1(a,ws,c)),H(m3(ws,a,d))}

    A-Priori Verification of Web Services with Abduction


    Example predefined answer

    Example: Predefined answer

    • Choreography

      • H(m1(X,ws,C)) → Echor(m2(ws,X,D)) \/ Echor(m3(ws,X,D))

    • Web service

      • H(m1(X,ws,C)) → Ews(m2(ws,X,D))

    • Result: feeble and strong conformant

    A-Priori Verification of Web Services with Abduction


    Ongoing work

    Ongoing work

    • Is a uniform language good w.r.t expressiveness?

    • Automatic translation from graphical notations

    • Experimentation and (performance) comparison with other frameworks

    A-Priori Verification of Web Services with Abduction


    A priori verification of web services with abduction1

    A-Priori Verification of Web Services with Abduction

    Marco Alberti1

    Federico Chesani2

    Marco Gavanelli1

    Evelina Lamma1

    Paola Mello2

    Marco Montali2

    Thank

    You!

    1 ENDIF, Università di Ferrara

    2 DEIS, Università di Bologna


  • Login