网络实时系统的一种活动性描述语言*

介绍了ADL,它是一种基于网络实时系统的活动性描述语言,一种描述并发处理中时态和功能行为的新的形式规格说明符号.ADL专用于计算机网络,是DORIS的一种形式语言扩充.它组合了状态机活动(ASM)的图形符号和基于模型的活动功能行为(AFB)符号;提供了关于ASM的抽象语法和静态、动态语义.最后通过一个小实例说明该语言是如何解释指定网络实时系统的.     

Evaluating a graphical notation for modelling software development methodologies

This work aims at evaluating a graphical notation for modelling software (and other kinds of) development methodologies, thus demonstrating how useful the graphical aspects can be for sharing knowledge between the people responsible for documenting information and those responsible for understanding and putting it into practice. We acknowledge the importance of having a common set of symbols that can be used to create, use and disseminate information for a larger audience than is possible today with a variety of alternatives and lack of a common ground. Using a cognitive dimensions framework, we make a standard evaluation of the elements and diagrams of the notation proposed to support the ISO/IEC 24744 methodology metamodel standard, considering the trade-offs between different dimensions. We suggest improvements to this existing notation based on this analysis, in the context of improving communication between creators and users of methodologies.     

结合形式化的面向对象设计方法与支撑系统

为了有效地结合形式化和非形式化设计方法各自的优点,克服其不足之处,以尽可能保证软件设计的质量与可靠性,文章提出了一种将形式化方法与非形式化的面向对象设计方法ＨＯＯＤ（ｈｉｅｒａｒｃｈｉｃａｌｏｂｊｅｃｔ－ｏｒｉｅｎｔｅｄｄｅｓｉｇｎ）相结合的途径,并介绍了其机器支撑环境的设计与实现．该途径在对层次式面向对象设计方法ＨＯＯＤ进行必要扩充的基础上,有机地集成了Ｚ语言等形式规约技术．支持这一途径的支撑环境提供了一套方便灵活的图形构筑工具、语法制导的形式语言与文本编辑工具,以及自动检查机制等．     

Experience of using a lightweight formal specification method for a commercial embedded system product line

A simple specification method is introduced and the results of its application to a series of projects in Philips are reported. The method is principally designed to ensure that that every unusual scenario is considered in a systematic way. In practice, this has led to high-quality specifications and accelerated product development. While the straightforward tabular notation used has proved readily understandable to non-technical personnel, it is also a formal method, producing a model of system behaviour as a finite state machine. In this respect, the notation is unusual in being designed to preserve as far as possible a view of the overall system state and how this changes. The notation also features a constraint table which may be described as a kind of spreadsheet for invariants to help define the states of the system.

The Construction of Minimal DNA Expressions

We describe a formal language/notation for DNA molecules that may contain nicks and gaps. The elements of the language, DNA expressions, denote formal DNA molecules. Different DNA expressions may denote the same formal DNA molecule. We analyse the shortest DNA expressions denoting a given formal DNA molecule. We determine lower bounds on their lengths and explain how we construct these minimal DNA expressions.     

Modelling an Extended/Virtual Enterprise by the Composition of Enterprise Models

We study how composition of enterprise models can represent the behaviour of an extended/virtual enterprise. Each enterprise manufactures discrete-parts products and is modelled with three concepts: product-related resources, processes and business goals (customer and purchase orders). Composition makes possible two forms of interaction between enterprises: matching customer and purchase orders and sharing processes which cross organisational boundaries. Models and their composition are represented in a formal notation.     

Commonsense approach to process modeling

The first phase of the three-phase ProSLCSE project, a US government-sponsored effort to give users of the Software Life-Cycle Support Environment (SLCSE) the ability to model and then execute processes, is described. The emphasis of the first phase is on providing a complete notation and vernacular for process definition. The proposed modeling notation includes infrastructure-modeling, information-modeling, and process-modeling notations that are intended to be easy to learn and use, even by busy project managers. The process concepts, modeling concepts, modeling notation, and process enactment of ProSLCSE are discussed     

UML建模过程及在需求分析中的应用

UML是建立系统模型和分析业务处理流程的强有力的工具,从不同的角度描述系统,帮助分析人员弄清楚系统“做什么,谁做,如何做,何时做,以什么顺序做”。描述使用UML的需求建模过程,并说明在稽查征费系统需求分析中的应用、获得的经验及注意事项。     

What Kind of Verification of Formal Navigation Modelling for Reliable and Usable Web Applications?

In this paper we introduce briefly a notation dedicated to model navigation of Web applications and we discuss some strategies to assess the usability over navigation models built with such as a notation. Our aim with this kind of evaluation is to ensure (prior to implementation) that important users tasks can (or cannot) be performed using the system.     

A formal software development approach using refinement calculus

The advantage of COOZ(Complete Object-Oriented Z) is to specify large scale software,but it does not support refinement calculus.Thus its application is comfined for software development.Including refinement calculus into COOZ overcomes its disadvantage during design and implementation.The separation between the design and implementation for structure and notation is removed as well .Then the software can be developed smoothly in the same frame.The combination of COOZ and refinement calculus can build object-oriented frame,in which the specification in COOZ is refined stepwise to code by calculus.In this paper,the development model is established.which is based on COOZ and refinement calculus.Data refinement is harder to deal with in a refinement tool than ordinary algorithmic refinement,since data refinement usually has to be done on a large program component at once.As to the implementation technology of refinement calculus,the data refinement calculator is constructed and an approach for data refinement which is based on data refinement calculus and program window inference is offered.     

Introduction to formal methods of software design

The potential benefits of using formal methods in the design of software are discussed. Concepts are illustrated by several small examples, with the objective of helping to bridge the gap between theory and practice. The paper introduces and explains some of the terminology, symbols and notation for the discrete mathematics used in the formal methods literature, intended to assist the reader in further study.     

Structuring formal specifications—a lesson relearned

Specifications written in the formal specification language Z often make use of a form of decomposition that is novel to programmers. A published Z specification is rewritten using the form of decomposition familiar to programmers. Whenever decomposition is used, there must be some strategy for deciding what is to go in one component and what is to go in another. At the highest level, the strategy underlying the rewritten specification is the well-known strategy of separating user interface issues from deeper system functionality issues. The effectiveness of the strategy is put to a simple test by showing how a modification to the interface can be supported by a modification to only part of the specification. The conclusions drawn are that care over decomposition is important in specifications, just as it is in programs, and that lessons learned from programming about effective decomposition strategies can be applicable at the specification level, too. In particular, the lesson relearned is that it is important to separate information about a system's functionality from information about how this functionality is presented to users.     

Encouraging serendipity in research: Designing technologies to support connection-making

Mobile applications have the ability to present information to users that is influenced by their surroundings, activities and interests. Such applications have the potential to influence the likelihood of individuals experiencing ‘serendipity’, through a combination of information, context, insight and activity. This study reports the deployment of a system that sends push text suggestions to users throughout the day, where the content of those messages is informed by users’ experience and interests. We investigated the responses to and interactions with messages that varied in format and relevance, and which were received at different times throughout the day. Sixteen participants were asked to use a mobile diary application to record their experiences and thoughts regarding information that was received over a period of five consecutive days. Results suggest that participants’ perception of the received suggestions was influenced by the relevance of the suggestion to their interests, but that there were also positive attitudes towards seemingly irrelevant information. Qualitative data indicates that participants, if in an appropriate time and place, are willing to accept and act upon push suggestions as long as the number of suggestions that they receive is not overwhelming. This study contributes towards an understanding of how mobile users make connections with new information, furthering our understanding of how serendipitous connections and insightful thinking could be accommodated using technology.     

The formal definition of semantics by string automata

An abstract machine called a string automaton (SA) is introduced in this paper. SAs are motivated by the need to formally define the semantics of programming languages in a manner accessible to the users of the language. The SA notation can be used to represent functions and computations in a clear, concise, graphical, and natural manner. After the class of SAs has been formally defined, it is shown how logic modules (resembling hardware circuit elements) and function modules (which define functions) can be expressed by SAs. Networks of SAs and their application to the construction of parsers is discussed. The definition of the language and hardware components of an interactive programming system by means of SAs is outlined.     

Concurrency and Refinement in the Unified Modeling Language

This paper shows how a formal notion of refinement may be defined for models, and model components, expressed in the Unified Modeling Language (UML). A formal, behavioural semantics is given to combinations of class, object, and state diagrams, using the notation of Communicating Sequential Processes (CSP); this semantics is adequate for the analysis of concurrent, communicating behaviour, and induces a notion of refinement for UML based upon existing notions of traces and failures refinement for CSP.     

Improving Web usability with the link lens

A number of factors may influence Web users' choice of which links to follow. These include assumptions about document quality and anticipated retrieval times. The present generation of World Wide Web browsers, however, provide only minimal support to assist users in making informed decisions. Web browser `link user interfaces' typically only display a document's Universal Resource Locator (URL), whilst a simple binary colour change in the URL's anchor is used to indicate its activation history. The question then is, how do users deal with the problem of having to make such decisions when the information at hand is insufficient? We have been conducting an investigation of how users make link selections.The results show users often are forced to fall back on heuristics and improvising strategies drawn from past experience. Based upon these results, we present a prototype of the `link lens', an enhanced link user interface designed to make such decisions easier and more productive for all users and help less experienced ones gain a better understanding of Web behaviour.     

计算机网络协议的形式模型研究

本文讨论了计算机网络协议的一种抽象形式模型。文中利用该模型对该通信协议的某些重要概念及性质进行了定义和形式描述,研讨了某些典型形式描述技术：Ｐｅｔｒｉ网,ＬＯＴＯＳ和关系表示法之间的语义联系。