VERIFICATION OF ASPECT ORIENTED MODELS BY DON MARTIN JAYASHREE VENKIPURAM PATHANGI PIYUSH SRIVASTAVA REFERENCES F. Mostefaoui and J. Vachon,” Design level Detection of Interactions in Aspect-UML models using Alloy”, Journal of Object Technology, vol. 6, no.7, Special Issue: Aspect-Oriented Modeling, pp 137–165, B. Bordbar, “UML2ALLOY: A Tool For Lightweight Modelling Of Discrete Event Systems,” In Proceedings of IADIS Applied Computing (Algarve, Portugal, February 22, 2005) G. Georg, “An Aspect-oriented Methodology for Designing Secure Applications,” Information and Software Technology, vol. 51, no. 5, pp , F. Mostefaoui and J. Vachon,”Verification of Aspect-UML models using Alloy,”In Proceedings of the 10 th International workshop on Aspect-Oriented Modeling (Van Couver, Canada, March, 2007) pp

VERIFICATION OF ASPECT-ORIENTED MODELS Review of Aspect-Oriented Definitions Aspect – crosscutting concern that may involve multiple classes Pointcut – tells where and when to insert code in a program Joinpoint – actual location to insert code Advice – functional code to implement aspect

ASPECT ORIENTED PROGRAMMING Improves modularity Clean separation of concerns Enables incremental improvements by interweaving aspect code into base program Difficult to predict the effect of a given aspect on the base program

VERIFICATION Formal verification and analysis of AO system model Consider AO model written in Aspect UML Aspect interactions verified using Alloy model analyzer

ASPECT INTERACTION PROBLEMS Violation of local properties: An advice or a join point’s pre/post condition is violated due to the weaving of an aspect Violation of a class, aspect or system invariant due to the addition of an aspect

TELECOM SYSTEM (Aspect UML)

UML2Alloy UML Semi Formal Language Not easy to perform verification and automated analysis Alloy Formal Language Allows verification and automated analysis Increases reliability of software systems

UML2Alloy Need not be familiar with Alloy Create a model in UML Convert it to an Alloy Model using UML2Alloy (Automated) Specify an OCL statement. Tool transforms this statement into alloy and evaluates it on th e alloy model

PROCESS FOR ANALYSIS (use Aspect-UML or UML2ALLOY)

VERIFICATION OF UML MODELS WITH ALLOY What is Alloy Analyzer? Formal language for structured modeling based on first order logic and ideas from Z (need Java5 RTE) Used for verification of agent-oriented, service- oriented, and aspect-oriented models Provides verification for interactions

ALLOY ANALYZER FEATURES Provides a structured specification consisting of the following types of elements: signatures, facts, predicates, and assertions Checks small model instances Provides an automatic analysis 1) simulation - evaluates predicates (states of the model) for consistency 2) checking – proves validity of assertions

UML2Alloy – Transformation Rules

EXAMPLE: SECURITY SYSTEM SECURITY SYSTEM DESIGN METHODOLOGY

MAN IN THE MIDDLE ATTACKER

SOLUTION TO PROBLEM The security mechanism for authentication chosen was TLS which involved passing certificates between a client and server. The mechanism was verified by the Alloy Analyzer.