Verifying a signature architecture: a comparative case study

We report on a case study in applying different formal methods to model and verify an architecture for administrating digital signatures. The architecture comprises several concurrently executing systems that authenticate users and generate and store digital signatures by passing security relevant data through a tightly controlled interface. The architecture is interesting from a formal-methods perspective as it involves complex operations on data as well as process coordination and hence is a candidate for both data-oriented and process-oriented formal methods. We have built and verified two models of the signature architecture using two representative formal methods. In the first, we specify a data model of the architecture in Z that we extend to a trace model and interactively verify by theorem proving. In the second, we model the architecture as a system of communicating processes that we verify by finite-state model checking. We provide a detailed comparison of these two different approaches to formalization (infinite state with rich data types versus finite state) and verification (theorem proving versus model checking). Contrary to common belief, our case study suggests that Z is well suited for temporal reasoning about process models with complex operations on data. Moreover, our comparison highlights the advantages of proving theorems about such models and provides evidence that, in the hands of an experienced user, theorem proving may be neither substantially more time-consuming nor more complex than model checkin

Computerization of workflows, guidelines and care pathways: a review of implementation challenges for process-oriented health information systems

There is a need to integrate the various theoretical frameworks and formalisms for modeling clinical guidelines, workflows, and pathways, in order to move beyond providing support for individual clinical decisions and toward the provision of process-oriented, patient-centered, health information systems (HIS). In this review, we analyze the challenges in developing process-oriented HIS that formally model guidelines, workflows, and care pathways. A qualitative meta-synthesis was performed on studies published in English between 1995 and 2010 that addressed the modeling process and reported the exposition of a new methodology, model, system implementation, or system architecture. Thematic analysis, principal component analysis (PCA) and data visualisation techniques were used to identify and cluster the underlying implementation ‘challenge’ themes. One hundred and eight relevant studies were selected for review. Twenty-five underlying ‘challenge’ themes were identified. These were clustered into 10 distinct groups, from which a conceptual model of the implementation process was developed. We found that the development of systems supporting individual clinical decisions is evolving toward the implementation of adaptable care pathways on the semantic web, incorporating formal, clinical, and organizational ontologies, and the use of workflow management systems. These architectures now need to be implemented and evaluated on a wider scale within clinical settings

Conceptual basis for developing of trainig models in complex system software assembling generator

This paper presents conceptual basis for developing of training models of interactive assembling system for automatic building of application software systems, obtained during practical works over "Design and architecture of software systems" and "Object-oriented analysis and design" courses. The system is intended for practical demonstration of basic stages and operations in development of complex and critical software. This also includes a consideration of solutions for some substantial problems of complex systems software generation, such as: program module compatibility, formalization of computer interaction and choosing of formal model for human machine interface. In addition, several training model implementations are provided.Keywords: software generator, training models, interactive system

UML ACTION SEMANTICS FOR MODEL TRANSFORMATION SYSTEMS

The Action Semantics for UML provides a standard and platform independent way to describe the behavior of methods and executable actions in object-oriented system design prior to implementation allowing the development of highly automated and optimized code generators for UML CASE tools. Model transformation systems provide visual but formal background to specify arbitrary transformations in the Model Driven Architecture (the leading trend in software engineering). In the current paper, we describe a general encoding of model transformation systems as executable Action Semantics expressions to provide a standard way for automatically generating the implementation of formal (and provenly correct) transformations by off-the-shelf MDA tools. In addition, we point out a weakness in the Action Semantics standard that must be improved to achieve a stand-alone and functionally complete action specification language

Injecting continuous time execution into service-oriented computing

Service-Oriented Computing is a computing paradigm that utilizes services as fundamental elements to support rapid, low-cost development of distributed applications in heterogeneous environments. In Service-Oriented Computing, a service is defined as an independent and autonomous piece of functionality which can be described, published, discovered and used in a uniform way. SENSORIA Reference Modeling Language is developed in the IST-FET integrated project. It provides a formal abstraction for services at the business level. Hybrid systems arise in embedded control when components that perform discrete changes are coupled with components that perform continuous processes. Normally, the discrete changes can be modeled by finite-state machines and the continuous processes can be modeled by differential equations. In an abstract point of view, hybrid systems are mixtures of continuous dynamics and discrete events. Hybrid systems are studied in different research areas. In the computer science area, a hybrid system is modeled as a discrete computer program interacting with an analog environment. In this thesis, we inject continuous time execution into Service-Oriented Computing by giving a formal abstraction for hybrid systems at the business level in a Service-Oriented point of view, and develop a method for formal verifications. In order to achieve the first part of this goal, we make a hybrid extension of Service-Oriented Doubly Labeled Transition Systems, named with Service-Oriented Hybrid Doubly Labeled Transition Systems, make an extension of the SENSORIA Reference Modeling Language and interpret it over Service-Oriented Hybrid Doubly Labeled Transition Systems. To achieve the second part of this goal, we adopt Temporal Dynamic Logic formulas and a set of sequent calculus rules for verifying the formulas, and develop a method for transforming the SENSORIA Reference Modeling Language specification of a certain service module into the respective Temporal Dynamic Logic formulas that could be verified. Moreover, we provide a case study of a simplified small part of the European Train Control System which is specified and verified with the approach introduced above. We also provide an approach of implementing the case study model with the IBM Websphere Process Server, which is a comprehensive Service-Oriented Architecture integration platform and provides support for the Service Component Architecture programming model. In order to realize this approach, we also provide functions that map models specified with the SENSORIA Reference Modeling Language to Websphere Process Server applications

Distributed, cooperating knowledge-based systems

Some current research in the development and application of distributed, cooperating knowledge-based systems technology is addressed. The focus of the current research is the spacecraft ground operations environment. The underlying hypothesis is that, because of the increasing size, complexity, and cost of planned systems, conventional procedural approaches to the architecture of automated systems will give way to a more comprehensive knowledge-based approach. A hallmark of these future systems will be the integration of multiple knowledge-based agents which understand the operational goals of the system and cooperate with each other and the humans in the loop to attain the goals. The current work includes the development of a reference model for knowledge-base management, the development of a formal model of cooperating knowledge-based agents, the use of testbed for prototyping and evaluating various knowledge-based concepts, and beginning work on the establishment of an object-oriented model of an intelligent end-to-end (spacecraft to user) system. An introductory discussion of these activities is presented, the major concepts and principles being investigated are highlighted, and their potential use in other application domains is indicated

An object based algebra for specifying a fault tolerant software architecture

AbstractIn this paper we present an algebra of actors extended with mechanisms to model crash failures and their detection. We show how this extended algebra of actors can be successfully used to specify distributed software architectures. The main components of a software architecture can be specified following an object-oriented style and then they can be composed using asynchronous message passing or more complex interaction patterns. This formal specification can be used to show that several requirements of a software system are satisfied at the architectural level despite failures. We illustrate this process by means of a case study: the specification of a software architecture for intelligent agents which supports a fault tolerant anonymous interaction protocol

Ontological Map of Service Oriented Architecture Based on Zachman

Service orientation is an approach in the field of enterprise architecture, business information systems and software application that its main element is the service. Shared services is an organization model of sharing, across an organization. It enables collaboration among the functions/departments. Main motivations for shared services are sharing, promote efficiency, reduce cost, and support scalability. Despite of the widespread use of these two approaches in information technology, there is no tool to optimize the management of them. The aim of this study is Ontological map of service oriented architecture based on zachman framework to adapt it in the reference enterprise architecture framework through implementation ontology views on system architect software and as well as equivalent ontology component with UML diagrams. After the implementation of the suggested model, the results showed that ontology is a formal description and explicit display of objects, concepts and other entities in the relationship between them. In other words, there is a model that describe all that is in fact in to understandable language for the system. Thus the proposed establishes have association between all aspects of zachman framework, also to create a clear description of business concepts in the management of shared services and is effective to provide a unified platform for enterprise modeling

Requirement Capture, Formal Description and Verification of an Invoicing System

Projet VASY-RAThe Invoicing case study is a typical business system proposed by Henri Habrias as a common example for a contest on the capacity of particular formal methods to capture requirements from the client. For this, the case study is informally described by half a page of English text. In this report, we use the formal description technique LOTOS for requirement capture, formal description and verification of the Invoicing case study. First, we analyse and interpret the informal requirements of the case study using the LOTOS approach for description of systems. This leads to a set of twenty questions about the informal description. By answering to these questions, we obtain a high-level specification architecture that can be formalised. Then, we present the formal description of the case study in LOTOS and, for comparison, in E-LOTOS, the new version of LOTOS currently being standardized. Since LOTOS allows a balance to be struck between process-oriented and data-oriented modeling, descriptions in both styles are given. After that, we verify the LOTOS descriptions by model-checking using the CADP (CÆSAR/ALDEBARAN) toolbox. The underlying Labelled Transition System (LTS) models corresponding to various scenarios are generated using the CÆSAR compiler. We push further the analysis of the case study by formalizing in temporal logic six properties of the system. We verify these properties on the LTS models using the XTL model-checker. Finally, we study the equivalence of the process-oriented and data-oriented descriptions using the ALDEBARAN tool

A comparative study of computer models for friction and their influence on dynamics of the heavy rigid body on a horizontal surface

Using an example of a heavy rigid body moving on a horizontal surface and having with it a permanent contact the process of construction and verification for spatial dynamical models of the multibody systems is analyzed. Two approaches to formal representation of the models: object-oriented, and bond graph based are applied. Energy based similarities between these approaches are analyzed. A detailed description of the bond graph representation for the most general type of constraint is presented. It turned out the resulting total bond graph model of the multibody system dynamics always has exactly a so-called canonical junction structure. This representation has a tight correspondence with our object-oriented implementation of the mechanical constraint architecture. As an example Modelica implementation of several classes in the row for mechanical contact is investigated. Computer implementations for three examples of the heavy rigid body dynamics are under investigation: (a) the rattleback, (b) example of A. P. Markeev, (c) the Tippe- Top. Among all of three examples each one demonstrates in its own manner a peculiar dynamical behaviour