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Informing the Requirements Process with Patterns of Cooperative Interaction*

Ian Sommerville, David Martin, and Mark Rouncefield

Computing Department, Lancaster University, UK 

Abstract: The need to understand the social context within which work to be supported by computer-based systems takes place is broadly recognised within the RE community. Ethnographic studies have been used in particular to inform the requirements process from a social perspective. To make this accessible to requirements engineers, work in this area has focused on how to integrate and communicate ethnographic findings on a per project basis but scant attention has been paid to how findings from individual studies may be generalised and re-used for the purposes of RE in new settings. This paper is intended to introduce our resource of Patterns of Cooperative Interaction to the RE community. These patterns specifically compare and contrast a variety of ethnographic findings, discuss their relevance to design and provide an introduction to the analytic sensibilities of such studies.  We discuss how we developed patterns of interaction from a corpus of ethnographic studies, illustrate a selection of these patterns and suggest how the patterns collection can be used by requirements engineers as a means of highlighting potential social issues that are relevant to the system requirements and as a means of generating requirements that support social interaction.

 Keywords: Patterns, computer support for collaborative work, ethnography, requirements engineering.

 Received April 27, 2003 

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A Reflective Approach to Improve Learning and Teaching of Software Engineering in Large Groups

Mohammed Odeh 

Faculty of Computing, University of the West of England, UK 

Abstract: This research reports on the synthesis of a reflective approach to improve teaching and learning of software engineering in large groups. In addition, observations on the outcomes obtained from examination, group-project coursework, and informal feedback from students and tutors have been analysed. This resulted in discovering areas of deficiencies in undertaking group-projects, common areas where students’ performance was similar in both exam and coursework. This study led to devise specific controls on the management of group projects and the implementation of tighter links between lectures and both practical sessions and group-work.

Keywords: Software engineering education, reflective learning and teaching.

 
Received September 4, 2002; accepted May 13, 2003 
 

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Security Solutions for Jini-Based Applications

Ghita Kouadri Mostéfaoui

Department of Informatics, University of Fribourg, Switzerland

Abstract: Since its first release, Jini became a promising technology to build fault tolerant distributed systems. The actual Jini architecture however lacks a strong security model. Based on a concrete example, this paper aims at reviewing the main security architectures that have been proposed by the research community and presents an evaluation of them. This work may serve as a basis for securing Jini-based systems by selecting the set of solutions provided by each model, depending on the security needs introduced by each specific application. 

Keywords: Distributed systems, Jini, security architectures. 

Received January 28, 2003; accepted May 24,2003 

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Arabic Font Recognition Based on Templates 

Ibrahim Abuhaiba

Department of Electrical and Computer Engineering, Islamic University of Gaza, Palestine  

Abstract: We present an algorithm for a priori Arabic optical Font Recognition (AFR). First, words in the training set of documents for each font are segmented into symbols that are rescaled. Next, templates are constructed, where every new training symbol that is not similar to existing templates is a new template. Templates are sharable between fonts. To classify the font of a word, its symbols are matched to the templates and the fonts of the best matching templates are retained. The most frequent font is the word font.

 Keywords: Optical character recognition, optical font recognition, vertical normalization, template matching. 

Received January 29, 2003; accepted May 4, 2003

 
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Tabulated Modular Exponentiation (TME) Algorithm for Enhancing RSA Public  Key Encryption Speed

Hamza Ali and Hamed Fawareh

Department of Computer Science, Zarka Private University, Jordan

 
Abstract: Improving software algorithms is not an easy task, especially for increasing operating speed and reducing complexity. Different algorithms implemented in cryptosystems used the exponentiation modular arithmetic; they however, suffer very long time complexity. Therefore, faster algorithms are strongly sought. This paper provides fast algorithms for modular multiplication and exponentiation that are suitable for implementation in RSA and DSS public key cryptographic schemes. A comparison of the time complexity measurements for various widely used algorithms is performed with the aim of looking for an efficient combination for the implementation of RSA cryptosystem. Two such algorithms were proposed in this work. The first is a modified convolution algorithm for modular multiplication while the second is a Tabulated Modular Exponentiation (TME) algorithm based on the modified sign-digit algorithm. They are found to give significant overall improvement to modular exponentiation over that of the fastest algorithms studied.

 Keywords: Data security, cryptography, authentication, algorithms, RSA, DSS. 

Received February 2, 2003; accepted May 11, 2003

 
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Emergence in Collective Robotics: A Case Study

Soraya Kouadri Mostéfaoui

Department of Informatics, University of Fribourg, Switzerland 

Abstract: In this paper we propose a robotics framework for studying emergence and collective adaptation. We describe two sets of experiments, where a pool of heterogeneous Khepera robots, participate in adapting the collective behavior, without being aware of them but just in virtue of the design of their internal structure. The innovative aspect in our approach rests on a system integrating communication as an active and dynamic component in the adaptation, and not only as a static part of the robots interactions.    

 Keywords: Emergence, autonomous agents, collective robotics, communication, adaptation. 

Received February 19, 2003; accepted May 19, 2003 

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Networking Data Integrity: High Speed Architectures and Hardware Implementations

Nicolas Sklavos, Epaminondas Alexopoulos, and Odysseas Koufopavlou

Electrical and Computer Engineering Department, University of Patras, Greece

 

Abstract: Hash functions are widely used in encryption schemes and security layers of communication protocols (WAP, IPsec) for data integrity, digital signature and message authentication codes. In addition to the demanded high security level, the need for high performance is a major factor of the security implementations. In this work, ultra high speed architecture for the hardware implementation of both MD5 and SHA-1 is proposed. Both hash functions have been developed with VHDL description language and have been integrated in FPGA devices. The introduced MD5 implementation performance is equal to 2.1Gbps while SHA-1 proposed implementation achieves throughput equal to 2.3 Gbps. Both proposed implementations are compared in throughput, operating frequency and in the area-delay product, with other related works. From these comparisons, it is proven that the MD5 proposed implementation is better by a factor range from 700% to 1500%. The SHA-1 proposed implementation is better by about 800% to 1700% in the term of performance, compared with the other conventional works.

 Keywords: MD5, SHA-1, hash functions, hardware implementation, cryptography, wireless protocols security. 

Received February 24, 2003; accepted May 5, 2003 

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A Hybrid Trust Management Model for MAS Based Trading Society

Kanagaraj Krishna and Aizaini bin Maarof

Information Security Group, University of Technology Malaysia, Malaysia

Abstract: The widespread use of the Internet signals the need for a better understanding of trust as a basis for secure on-line interaction. In this paper we provide and discuss existing works on trust management models in the area of Multi Agent Systems (MAS) and highlight the shortcomings. Our proposed model is not presented as the final solution to the issue. This new model will have a mechanism that allows agents to manage trust not by just one way but a few combinations of different types of trust in different situations. The proposed model is concerned with the general notion of trust, one that goes beyond cryptographic protocols. Findings from this paper can be used for future research work in the area of trust in MAS and to address further the importance of trust management on the Internet. 

Keywords: Internet, trust management, MAS, hybrid approach, cryptography, untrustworthy agents. 

Received March 1, 2003; accepted May 12, 2003
 
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A Fault-Tolerant Routing Algorithm for 3-D Torus Interconnection Networks

Jehad Al-Sadi1, Khaled Day 2, Mohamed Ould-Khaoua3

1Department of Computer Science, Zarka Private University, Jordan

2Department of Computer Science, Sultan Qaboos University, Sultanate of Oman

3Department of Computing Science, University of Glasgow, UK 

Abstract: This paper describes a new fault-tolerant routing algorithm for 3-D tori using the concept of “probability vectors”. To compute these vectors, a node determines first its faulty set, which represents the set of all its neighboring nodes that are faulty or unreachable due to faulty links. Each node then calculates a probability vector, where the lth element represents the probability that a destination node at distance l cannot be reached through a minimal path due to a faulty node or link. The probability vectors are used by all the nodes to achieve an efficient fault-tolerant routing in the network. An extensive performance evaluation conducted in this study reveals that the proposed algorithm exhibits good fault-tolerance properties in terms of the achieved percentage of reachability and routing distances.

Keywords: Multicomputers, interconnec­tion networks, 3-D tori, fault-tolerant routing, performance evaluation. 

Received April 27, 2003; accepted May 12, 2003 

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