In this paper we describe the development and verification of software for an automotive Brake-by-Wire System. This is a new brake system without mechanical or hydraulic backup. The system is based on a time-triggered...
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ISBN:
(纸本)0769501915
In this paper we describe the development and verification of software for an automotive Brake-by-Wire System. This is a new brake system without mechanical or hydraulic backup. The system is based on a time-triggered communication architecture. The central control computer in this distributed system, called Brake-by-Wire Manager, is a redundant design in order to tolerate any single failure. The software of this computer is subject to a set of safety related requirements which must be verified. We have developed the software using synchronous software components based on the synchronous language ESTEREL. Many safety properties have been verified successfully and the software has been integrated in a prototype Brake-by-Wire system in a research car.
The ability to check whether the modeled system satisfies certain properties is a very important aspect in the software development process. Many object-oriented methods do not pay enough attention to behavioral descr...
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In this paper we investigate features of a parallel object server when used as a data repository in a CASE tool. We argue that hierarchical structures of fine grained objects are typical for data used by CASE tools, w...
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ISBN:
(纸本)0769501915
In this paper we investigate features of a parallel object server when used as a data repository in a CASE tool. We argue that hierarchical structures of fine grained objects are typical for data used by CASE tools, we describe the construction of the server;and the implementation of the prototype. The presented results of our experiments concern the question how the speedup depends on the number of processors involved, the number of users working simultaneously and the size of methods in classes.
The number of security-breaking attempts originated inside the organizations are increasing steadily. Attacks made in this way, usually done by 'authorized' users of the system, cannot be immediately located. ...
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The number of security-breaking attempts originated inside the organizations are increasing steadily. Attacks made in this way, usually done by 'authorized' users of the system, cannot be immediately located. As the idea of filtering the traffic at the 'entrance door' (by firewalls, for instance) is not completely successful, the use of other technologies should be considered to increase the defense capacity of a site. Therefore, the introduction of mobile agents to provide the computational security by constantly moving around within the internal infoways of an organization is presented as a natural solution to prevent both external and the internal sources of intrusion. This work presents an evaluation of the use of mobile agents mechanisms to add mobility features to the process of monitoring intrusion in computational systems. A modular approach is proposed, where independent small agents will monitor the communication paths. This approach presents significant advantages in terms of minimizing overhead, increasing scalability and flexibility and providing fault tolerance.
The concept of software architecture, also said system structure or system configuration, is especially important to design complex softwaresystems, providing a model of the large scale structural properties of syste...
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The concept of software architecture, also said system structure or system configuration, is especially important to design complex softwaresystems, providing a model of the large scale structural properties of systems. Module interconnection languages (MILs) introduced the idea of creating program modules and connecting them to form larger structures. However, MILs do not support the description of important architectural elements. A new class of description languages, referred to as architectural description languages (ADLs), have recently emerged. Most ADLs, however, support only the description of static software architectures and not dynamic or reconfigurable software architectures. A further limitation of current ADLs is that they focus mainly on the formal notation and usually do not offer proof systems and tools to enable designers to formally verify the properties of their designs. We have developed the ZCL framework, which is a formal framework, specified in Z, to describe and reason about dynamic distributedsoftware architectures. In this paper, we use a simple case study - the client-server system - to demonstrate how our formal framework ZCL can be used to specify and verify reconfigurable software architectures.
A novel concurrent programming paradigm called "Hypersequential Programming" (HSP) is being developed. HSP aims to eliminate all undesirable behaviours from a given application. A fundamental part of that sy...
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ISBN:
(纸本)0769501915
A novel concurrent programming paradigm called "Hypersequential Programming" (HSP) is being developed. HSP aims to eliminate all undesirable behaviours from a given application. A fundamental part of that system requires the use of test cases for the serialization of a program. Only those test cases found to be correct are used in the final concurrent program. Therefore, HSP relies on all the functionality being included into a program. This is opposite to traditional softwareengineering practice, which is to ensure that all unwanted behaviours have been removed. This paper briefly examines the HSP method with reference to test cases and scenarios. We examine a couple of brief examples and discuss the limitations of test cases, with particular respect to HSP. We concluded that finding a method of ensuring the correct set of test cases is used in development is essential to the success of HSP.
A general methodology based on softwareengineering principles is proposed for the parallelization of existing sequential code. The utility of the proposed methodology is evaluated through a case study involving a num...
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This paper investigates the use of object-oriented techniques for the specification and design of distributed multimedia applications (DMAs). DMAs are a class of software applications with a range of strong - often co...
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ISBN:
(纸本)0769501915
This paper investigates the use of object-oriented techniques for the specification and design of distributed multimedia applications (DMAs). DMAs are a class of software applications with a range of strong - often conflicting - requirements of dynamicity, interactivity, real-time synchronized processing of several media types, network distribution, high-performance, fault-tolerance, load balancing and security. The development of complex DMAs can benefit from the adoption of object design methods and distributed objects implementation technologies. The paper describes the use of two modeling approaches, based on the standard UML modeling language, and on the TRIO formal specification language, respectively. The problem of defining steps to move from the UML or TRIO specification to a CORBA IDL implementation is addressed too. An experimental distributed Video-on-Demand system is used throughout the paper as a case study.
This paper presents a theoretical and practical framework for constructing and reasoning about mobile agents. The framework is formulated as a process calculus and has two contributions. One of the contributions can m...
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This paper presents a theoretical and practical framework for constructing and reasoning about mobile agents. The framework is formulated as a process calculus and has two contributions. One of the contributions can model not only individual mobile agents but also a group of mobile agents because the calculus allows more than one mobile agent to be dynamically organized into a single mobile agent. The other contribution can exactly model many features of actual mobile agents, such as mobility and marshaling, which are often ignored in other existing frameworks but may seriously affect the correctness of mobile agents. To demonstrate the utility of the calculus, we constructed a practical mobile agent system whose agents can be naturally and strictly specified and verified in the calculus. The system also offers a security mechanism for mobile agents by using well-defined properties of the calculus.
This paper presents the SEEDS simulation environment for the evaluation of distributed traffic control systems. Starting with an overview of the general simulator architecture, the software modules and the derived har...
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ISBN:
(纸本)0769501915
This paper presents the SEEDS simulation environment for the evaluation of distributed traffic control systems. Starting with an overview of the general simulator architecture, the software modules and the derived hardware architecture of the simulation environment are described with respect to performance requirements. The communication architecture of the SEEDS simulator is based on the OMG's CORBA standard and the DIS simulation protocol. With the SEEDS prototype simulating airport ground-traffic, performance measurements evaluating critical design and implementation decisions are described. The main aspects of the performance analysis are the attained application performance using CORBA and DIS as communication middleware, and the scalability of the overall approach. The evaluation shows the appropriateness of the design of the simulation environment and the derived hard- and software architecture, which is flexible and open to further extensions. Moreover the combination of CORBA and DIS provides a suited platform for distributed interactive simulation purposes because of the adequate performance, high scalability, and the high-level programming model which allows to rapidly develop and maintain complex distributed applications with high-performance requirements.
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