Generating FSMs from interworkings

Summary. A technique for the automated synthesis of FSMs (finite state machines) from sets of interworkings (synchronous sequence charts) is described. This is useful for obtaining feedback from a set of scenarios during a system's definition phase or test phase. It is sound in the sense that the generated FSM only exhibits traces that correspond to one of the interworkings from the given set. It preserves deadlock freedom in the sense that no behaviours are lost. The concrete syntax of SDL is used to represent the resulting FSMs. Received: December 1996 / Accepted: September 1998     

PAG – an efficient program analyzer generator

The program analyzer generator PAG described in this paper attempts to offer the best of both worlds, specification languages based on the clean theory of abstract interpretation and efficient implementation methods from the theory of data flow analysis. PAG has a high level functional input language to specify data flow analyses. It offers the generation of complex data structures and is therefore not limited to bit vector problems. PAG generated interprocedural analyzers can be easily integrated into existing compilers. PAG has successfully been used in the ESPRIT project COMPARE to generate several analyzers (including alias analysis and constant propagation) for industrial quality ANSI-C and Fortran90 compilers, and is now marketed by the spin-off company AbsInt.A simplified version of PAG can be interactively tested over the Web.     

Specifying and Analysing System-Level Inter-Component Interfaces

In control systems, the interfaces between software and its embedding environment are a major source of costly errors. For example, Lutz reported that 20–35% of the safety-related errors discovered during integration and system testing of two spacecraft were related to the interfaces between the software and the embedding hardware. Also, the software’s operating environment is likely to change over time, further complicating the issues related to system-level inter-component communication. In this paper we discuss a formal approach to the specification and analysis of inter-component communication using a revised version of RSML (Requirements State Machine Language). The formalism allows rigorous specification of the physical aspects of the inter-component communication and forces encapsulation of communication-related properties in well-defined and easy-to-read interface specifications. This enables us both to analyse a system design to detect incompatibilities between connected components and to use the interface specifications as safety kernels to enforce safety constraints.     

Deriving Goals from a Use-Case Based Requirements Specification

Use cases and scenarios have emerged as prominent analysis tools during requirements engineering activities due to both their richness and informality. In some instances, for example when a project’s budget or schedule time is reduced at short notice, practitioners have been known to adopt a collection of use cases as a suitable substitute for a requirements specification. Given the challenges inherent in managing large collections of scenarios, this shortcut is cause for concern and deserves focused attention. We describe our experiences during a goal-driven requirements analysis effort for an electronic commerce application. In particular, we identify the specific risks incurred, focusing more on the challenges imposed due to traceability, inconsistent use of terminology, incompleteness and consistency, rather than on traditional software project management risks. We conclude by discussing the impact of the lessons learned for requirements engineering in the context of building quality systems during goal and scenario analysis.     

Generating diagnostic information for behavioral preorders

Summary.  This paper describes a method for generating diagnostic information that explains why a given finite-state system fails to be greater than its specification with respect to the prebisimulation preorder. The information takes the form of a logical formula satisfied by the specification but not by the system and thus may be used by system designers for debugging purposes. Our technique relies on modifying an algorithm for computing the prebisimulation preorder so that information needed for generating these distinguishing formulas is saved appropriately. As a number of other behavioral preorders may be characterized in terms of prebisimulation preorder, our approach may be used as a basis for computing diagnostic information for these relations as well. Received: August 1992/Accepted: May 1995     

Implementing the CORBA GIOP in a high-performance object request broker environment

The success of the Object Management Group's General Inter-ORB Protocol (GIOP) is leading to the desire to deploy GIOP in an ever-wider range of application areas, many of which are significantly more demanding than traditional areas in terms of performance. The well-known performance limitations of present day GIOP-based object request brokers (ORBs) are therefore increasingly being seen as a problem. To help address this problem, this paper discusses a GIOP implementation which has high performance and quality of service support as explicit goals. The implementation, which is embedded in a research ORB called Gopi, is modular and extensible in nature and includes novel optimization techniques which should be separately portable to other ORB environments. This paper focuses on the message protocol aspects of Gopi's GIOP implementation; higher layer issues such as marshalling and operation demultiplexing are not covered in detail. Figures are provided which position Gopi's GIOP performance against comparable ORBs. The paper also discusses some of the design decisions that have been made in the development of the GIOP protocol in the light of our implementation experience. Received: May 2000 / Accepted: December 2000     

Consistent specification of interface suites in UML

The paper motivates and describes a model oriented approach for consistent specification of interface suites in UML. An interface suite is a coherent collection of interfaces defining interactions that transcend component boundaries. The specification of interface suites contains diagrammatic views and documentation, but it is extended with templates for structured specifications deriving from the ISpec approach. To guarantee that the specification views, documentation and templates are consistent, a specification model has been constructed. The model contains both structural and behavioural information, represented in the form of sequences of carefully designed tuples. The model provides the underlying structure for the tool supporting the design process. The tool directs the designer to specify all elements of the model in a consistent way. The specification is collected both by customized specification templates and by diagrams. The documentation and the diagram elements – both derived from the template information – are automatically generated. This prevents errors and provides specification consistency. Initial submission: 15 February 2002 / Revised submission: 20 September 2002 Published online: 2 December 2002 RID="*" ID="*"Supported by PROGRESS grant EES.5141 and ITEA DESS grant IT990211.     

Measuring flow experience in an immersive virtual environment for collaborative learning

In contexts other than immersive virtual environments, theoretical and empirical work has identified flow experience as a major factor in learning and human–computer interaction. Flow is defined as a ‘holistic sensation that people feel when they act with total involvement’. We applied the concept of flow to modeling the experience of collaborative learning in an immersive virtual environment. The aims were, first, to psychometrically evaluate a measurement model of flow and, second, to test a structural model of flow. Pairs of small teams engaged in collaborative problem‐solving tasks while communicating by way of an immersive virtual environment. Flow was measured after each session, using Guo and Poole's inventory for measuring flow in human–computer interaction. In relation to the first aim, partial‐least‐squares analysis demonstrated strong evidence for the measurement model. In relation to the second aim, the structural model was supported: the effect of learning‐task characteristics on flow experience was mediated by its precursors, with extraneous variables held constant. It is reasoned that the experiment and resultant analysis of this work contributes to the development of measurement models and structural models of flow in immersive virtual environments.     

There’s More to Information Systems Development than Structured Approaches: Information Requirements Analysis as a Socially Mediated Process

Information systems (IS) development approaches are considered with particular reference to those aspects of the process most concerned with the determination of information requirements. The majority can be classified as adopting a unitary, objective perspective. This perspective fails to recognise the interpretative, inter-subjective nature of information and the importance of informal as well as formal data-processing systems. This paper aims to contribute to the discussion on socio-technical and soft approaches to IS development by providing a contrasting perspective on information requirements analysis as a process which is socially mediated. A framework is developed which places information requirements analysis in the context of strategic IS development. This locates social communication networks centrally in this process and raises implications for the practice of IS development, and of information requirements analysis.     

Adjacency matrix generation from the image of graphs: a morphological approach

This paper presents a system for automatic generation of the adjacency matrix from the image of graphs. The graph, we assume, is printed or hand printed and available as a part of a document either separately or along with text and picture. A morphology-based approach is used here to separate components of the graphs: vertices, edges and labels. A novel technique is proposed to traverse the nonplanar edges joining the vertices. The proposed method may be used for logical compression of the information contained in the graph image in the form of an adjacency matrix. It may also be used to replace the cumbersome, error-prone and time-consuming manual method of generation of the adjacency matrix for graphs with large number of vertices and complex interconnections.     

An approach to effortless construction of program animations

Program animation systems have not been as widely adopted by computer science educators as we might expect from the firm belief that they can help in enhancing computer science education. One of the most notable obstacles to their adoption is the considerable effort that the production of program animations represents for the instructor. We present here an approach to reduce such a workload based on the automatic generation of visualizations and animations. The user may customize them in a user-friendly way to construct more expressive program animations. These operations are carried out by means of a user-friendly manipulation based on the metaphor of office documents. We have applied this approach to the functional paradigm by extending the WinHIPE programming environment. Finally, we report on the successful results of an evaluation performed to measure its ease of use.     

Learning response time for WebSources using query feedback and application in query optimization

Abstract. The rapid growth of the Internet and support for interoperability protocols has increased the number of Web accessible sources, WebSources. Current wrapper mediator architectures need to be extended with a wrapper cost model (WCM) for WebSources that can estimate the response time (delays) to access sources as well as other relevant statistics. In this paper, we present a Web prediction tool (WebPT), a tool that is based on learning using query feedback from WebSources. The WebPT uses dimensions time of day, day, and quantity of data, to learn response times from a particular WebSource, and to predict the expected response time (delay) for some query. Experiment data was collected from several sources, and those dimensions that were significant in estimating the response time were determined. We then trained the WebPT on the collected data, to use the three dimensions mentioned above, and to predict the response time, as well as a confidence in the prediction. We describe the WebPT learning algorithms, and report on the WebPT learning for WebSources. Our research shows that we can improve the quality of learning by tuning the WebPT features, e.g., training the WebPT using a logarithm of the input training data; including significant dimensions in the WebPT; or changing the ordering of dimensions. A comparison of the WebPT with more traditional neural network (NN) learning has been performed, and we briefly report on the comparison. We then demonstrate how the WebPT prediction of delay may be used by a scrambling enabled optimizer. A scrambling algorithm identifies some critical points of delay, where it makes a decision to scramble (modify) a plan, to attempt to hide the expected delay by computing some other part of the plan that is unaffected by the delay. We explore the space of real delay at a WebSource, versus the WebPT prediction of this delay, with respect to critical points of delay in specific plans. We identify those cases where WebPT overestimation or underestimation of the real delay results in a penalty in the scrambling enabled optimizer, and those cases where there is no penalty. Using the experimental data and WebPT learning, we test how good the WebPT is in minimizing these penalties. Received June 22, 1999 / Accepted December 24, 1999     

ObjectGlobe: Ubiquitous query processing on the Internet

We present the design of ObjectGlobe, a distributed and open query processor for Internet data sources. Today, data is published on the Internet via Web servers which have, if at all, very localized query processing capabilities. The goal of the ObjectGlobe project is to establish an open marketplace in which data and query processing capabilities can be distributed and used by any kind of Internet application. Furthermore, ObjectGlobe integrates cycle providers (i.e., machines) which carry out query processing operators. The overall picture is to make it possible to execute a query with – in principle – unrelated query operators, cycle providers, and data sources. Such an infrastructure can serve as enabling technology for scalable e-commerce applications, e.g., B2B and B2C market places, to be able to integrate data and data processing operations of a large number of participants. One of the main challenges in the design of such an open system is to ensure privacy and security. We discuss the ObjectGlobe security requirements, show how basic components such as the optimizer and runtime system need to be extended, and present the results of performance experiments that assess the additional cost for secure distributed query processing. Another challenge is quality of service management so that users can constrain the costs and running times of their queries. Received: 30 October 2000 / Accepted: 14 March 2001 Published online: 7 June 2001     

Deductive tools of an algebraic programming system

A mathematical environment is a system of tools supporting interactive manipulation of knowledge represented in the form of (formalized) mathematical texts. A theoretical substantiation of a project proposed is the theory of interaction of agents and environments. At the present time, this theory is realized on the basis of a simulator of an action language developed in an algebraic programming system called APS. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 17–34, January–February, 2000.     

Entrepreneurial Innovations in Gujarat

Gujarat has been identified as an enterpreneurial hub of India, primarily due to the innovative behaviour of Gujarati entrepreneurs. This has led Gujarat to become known as a model of enterpreneurial innovations. This model of enterpreneurial innovations has been developed from a study of entrepreneurs in a variety of industries from the region and several industrial clusters of enterprises in Gujarat. The study points to the transformation of many communities, particularly the Patel community, which was traditionally an agricultural community, into a manufacturing class and a new emergent in Gujarat’s industrial scenario.     

An Indigenous Process of Pedagogic Innovation: A Case Study on Curriculum Development

We describe our attempts at curriculum development at the undergraduate level working within the constraints of a large traditional university system. Curriculum reform is described as a three-step process of product innovation, accommodation and assimilation. In a dual-pronged strategy, students are constructively engaged, first, in investigative projects and assigned specific tasks, giving them a flavour of creative research, and, second, in development of curricular products. The process of transfer of pedagogic innovations into the formal classroom is enhanced by a teacher training programme that aims to provide experiential learning of research-based innovative teaching practices, catalyse a process of reflection through classroom research and establish a collaborative network of teachers.     

Networks of Science and Technology in India: The Elite and the Subaltern Streams

The paper investigates the structure and functioning of the science and technology (S&T) system in India as it has evolved in the post-independence period (1947 onwards). The networks of entities involved in S&T actions, the paper argues, can be categorised, in terms of adopted approaches to agenda and priority setting and accounting for actions, into two streams. The origins and expansion of the two streams are traced. One, the ‘Elite’ stream (high profile and visibility linked to big industry), adopting what the paper has generically termed the ‘Nehruvian’ model of development, is shown to have emerged as a dominant network. The other socially powerful ‘Subaltern’ stream (less visible, closer to ground realities and linked to village and cottage industry), adopting the ‘Gandhian’ model of development, still remains dispersed and outside the consideration of high-level decision-making bodies. The paper stresses the importance of moving the support and attention from the dominant stream to efforts that attempt a synthesis between the dominant and the subaltern.