Research Papers - Dept of Software Engineering

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Integrating industrial technologies, tools and practices to the IT curriculum: an innovative course with .NET and java platforms
(acm.org, 2005-10-20) Athauda, R; Kodagoda, N; Wickramaratne, J; Sumathipala, P; Rupasinghe, L; Edirisighe, A; Gamage, A; De Silva, D
Exposure to state-of-art industry technologies, tools and practices by students provide CS/IT graduates highly desirable skills and marketability. A key expectation of the industry from their new cadre is a speedy integration into the business environment resulting in productive work. This usually requires having a sound technological background, a maturity to assess the environment and adapt quickly, and highly-developed soft skills to be productive in a team environment. Incorporating such experience and skills into a CS/IT curriculum is challenging and is still in its infancy stages. We undertook such as an endeavor in integrating .NET into the IT curriculum. Microsoft's .NET platform is becoming increasingly popular in the industry. Incorporating .NET into the undergraduate IT curriculum provides a plethora of skills and increases the employability of our graduates. We integrated .NET without a major revision to the existing curriculum by introducing an optional course in the final year (senior-level) of the IT undergraduate program. In addition to the .NET platform, the course covered the Java platform, which is similar in architecture to .NET. The course emulated an industry-based environment with real-world based assignments, focused on deliverables, used state-of-art IDEs and documentation, and pair programming to create a highly productive environment. The “soft skills” were integrated into the course with a project that implemented a virtual marketplace. Students in groups played different entities in the virtual marketplace and communicated with each other via Web Services. The project provided a virtual business environment and exposure to teamwork, collaboration, competition, negotiating, and creativity skills. Our first offering of the course in semester 1, 2005, attracted 128 students. The course created a highly productive environment throughout the semester. Students completed 7 assignments and the project within the 14-week semester. The initial results are encouraging and provide many insights to CS/IT departments planning to incorporate such courses.
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Internal structure and semantic web link structure based ontology ranking
(IEEE, 2008-12-12) Rajapaksha, S. K; Kodagoda, N
The semantic Web is an extension of the World Wide Web with new technologies and standards that enable interpretation and processing of data and useful information for extraction by a computer. The World Wide Web Consortium (W3C) recommends XML, XML schema, RDF, RDF schema and Web Ontology Language (OWL) as standards and tools for the implementation of the semantic Web. Ontologies work as the main component in knowledge representation for the semantic Web. It is a data model that represents a set of concepts and the relationships between those concepts within a domain. Building an ontology starting from scratch is not an easy task since it makes heavy demands on time in addition to expert knowledge related to the domain. However, we can use the existing ontologies to develop semantic Web applications. But, there are a large number of ontologies available and the ontology search engine will generate a bulk of results with different ontologies for search queries. Therefore, ranking of ontologies is needed to find the most appropriate and relevant ontologies. We consider the ranking techniques and algorithms attached to the semantic Web: (i) Swoogle Ranking (ii) Ontokhoj Ranking (iii) OntoQA Ranking (iv) AKTiveRank (v) OntoSearch Ranking (vi) content-based ontology ranking (vii) SemSearch Ranking (viii) ReConRank. Our effort considers most popularly used ranking techniques and algorithms attached to the semantic Web. We analyze the above ontology ranking techniques with algorithms and then mainly categorize into two groups. One group is based on the semantic Web link structure and the other one is based on internal structure of the ontology. We identify that some features are not addressed in ranking of ontologies selected by the above ranking techniques and algorithms. Therefore, we propose a ranking method that considers both internal structure and semantic Web link structure of ontologies to improve the ranking of ontologies. We finally evaluate the proposed ranking method. According to the results with evaluation, we allocate more weighting for internal structure and low weighting for semantic Web link structure to get the best ranking results.
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Voizlock-human voice authentication system using hidden markov model
(IEEE, 2008-12-12) Maduranga, R. G; Jayamaha, M; Senadheera, M. R. R; Gamage, T. N. C; Weerasekara, K. D. P. B; Dissanayaka, G. A; Kodagoda, N
Speaker authentication is the process of automatically recognizing who is speaking on the basis of individual information included in speech waves. Many principles are used in the area of voice recognition. This paper provides a method of storing the voiceprints of individuals uniquely, based on the Hidden Markov Model. HMM has been used in the speech recognition area for a long period of time, but VoizLock project explores a way of using HMM for voice authentication which is different from speech recognition. This voiceprint will then be used for voice authentication, using text-independent speaker recognition methods in which the system does not rely on a specific text being spoken, but solely on the voice of the speaker. This paper also provides details about certain misconceptions with regard to voice authentication that exist in the society. This paper explains more about the user training phase detailing how the voice print of an individual is stored in the system by extracting certain values of the waveform using HMM. Apart from the training phase this analyses the results obtained from the testing done covering different scenarios pertaining to voice authentication.
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Eigenface based automatic facial feature tagging
(IEEE, 2008-12-12) Wijeratne, S; Jayawardena, S; Jayasooriya, S; Lokupathirage, D; Patternot, M; Kodagoda, N
There are several approaches to search databases of faces. However such methods still require a significant use of humans to interpret an eyewitness account and so forth. In many cases these searches are done using visual building tools as creating a graphical face model. A system that can easily interface with general users should directly search a person by description given verbally or textually. This would reduce costs in the search process. Facial feature characteristics identification would act as a stepping stone in cataloguing large face databases automatically thus providing the possibility of a description based face search by text. This paper presents the possibility of utilizing eigenface approach to recognize different characteristics of a facial feature and assigning descriptive words such as "Large", "Small" to each feature. After training the system, it would automatically attempt to match a pattern in the training set that best describes the input image and output a tag associated with it. This effectively allows an image of a person's face to be tagged by his or her feature characteristics. While utilizing the standard set steps as defined in the eigenface algorithm, slight modifications are done in the algorithm that matches input images with ones in the training set. The training set defined has a very huge impact for the final outcome, and due to the subjective nature of the training, future research would be done on this regard. The investigation showed that the method works fine with well defined features such as eyes but fails for features such as foreheads due to the lack of significant differences or characteristics between such features. Hence it is seen that while eigenface can be used for the categorization of well defined features, it is unable by itself to create a system that can cover all features of a face.
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Mobile based GIS for dynamic map generation and team tracking
(IEEE, 2010-12-17) Karunarathne, D; Gunasekara, T; Dias, D; Kasthurirathne, D
We present an effective solution for both digital map generation and real time user tracking for teams operating in hazardous environments or unfamiliar territory. The system is based on the client server model, where the client is a GPS enabled mobile phone which is capable of capturing coordinates and serving dynamic maps to the user. The maps plot the team's navigational routes and enables real time tracking of each other. The server builds a GIS at the back end based on the data sent by the users, and also develops maps on demand. The system is implemented with simple hardware and uses the available GPRS network for data gathering. This enables the system to be used both in hazardous environments and by the general public.
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Architectural description based Overlay Networks
(2011-09-01) Kasthurirathna, D; Keppetiyagama, C
Overlay Networks are heavily used in Distributed computing applications. They often have heterogeneous architectures, such as Client Server, Peer to Peer or Hybrid. In this work, we try to abstract the Architecture of an Overlay Network into a document called an Architectural Description (AD). The Architectural Description document may contain the Roles and the Relationships of a particular Overlay Architecture. The Architectural Description documents may be exchanged among the nodes and parsed by the nodes themselves, enabling the nodes to adopt different roles and relationships. By introducing a new AD, a new Overlay Network can be formed dynamically. AD based Overlay Networks may open many new possibilities in Overlay Networking. This approach would allow heterogeneous Overlays to work collaboratively, while maintaining their respective Security settings using 'Security Roles'. It would also allow multiple overlays to be dynamically 'super-imposed' on top of each other. Apart from that, the AD based approach would allow the same set of nodes to switch between heterogeneous overlays at different time intervals. Architectural Descriptions can also be used as an efficient means of Security key management. A prototype framework was developed to explore these features, using sample distributed file sharing applications. Moreover, the possible enhancements and future directions of AD based approach in developing Overlay Networks are also discussed.
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Applicability of three complexity metrics
(IEEE, 2012-12-12) De Silva, D. I; Kodagoda, N; Perera, H
Over the years a number of complexity metrics have been proposed. However, there have been only a few studies conducted to compare those proposed metrics in terms of their practical applicability. The few researches that have been conducted to assess the applicability of a complexity metric have also used the five properties proposed by Briand et al. However determining whether a complexity measure satisfies some theoretical complexity properties is not a reliable method of determining the practical applicability of it. Thus, the main intent of this study was to compare three proposed code complexity metrics: McCabe's cyclomatic complexity, Halstead's software science and Shao and Wangs' cognitive functional size and identify which metric is the most suitable metric that can be used in the current state of the art with the help of thirty programmers. To conduct this empirical study ten freely available java programs were used as the base. From this study it was identified that Shao and Wangs' cognitive functional size is the best complexity metric that can be used in the real world.
Open Access
On the influence of topological characteristics on robustness of complex networks
(Journal of Artificial Intelligence and Soft Computing Research, 2013) Kasthurirathna, D; Piraveenan, M; Thedchanamoorthy, G
In this paper, we explore the relationship between the topological characteristics of a complex network and its robustness to sustained targeted attacks. Using synthesised scale-free, small-world and random networks, we look at a number of network measures, including assortativity, modularity, average path length, clustering coefficient, rich club profiles and scale-free exponent (where applicable) of a network, and how each of these influence the robustness of a network under targeted attacks. We use an established robustness coefficient to measure topological robustness, and consider sustained targeted attacks by order of node degree. With respect to scale-free networks, we show that assortativity, modularity and average path length have a positive correlation with network robustness, whereas clustering coefficient has a negative correlation. We did not find any correlation between scale-free exponent and robustness, or rich-club profiles and robustness. The robustness of small-world networks on the other hand, show substantial positive correlations with assortativity, modularity, clustering coefficient and average path length. In comparison, the robustness of Erdos-Renyi random networks did not have any significant correlation with any of the network properties considered. A significant observation is that high clustering decreases topological robustness in scale-free networks, yet it increases topological robustness in small-world networks. Our results highlight the importance of topological characteristics in influencing network robustness, and illustrate design strategies network designers can use to increase the robustness of scale-free and small-world networks under sustained targeted attacks.
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Centrality and composition of four-node motifs in metabolic networks
(Elsevier, 2013-01-01) Piraveenan, M; Wimalawarne, K; Kasthurirathn, D
Analysing subgraph patterns and recurring motifs in networks is a useful way to understand their local topology and func- tion. Motifs have been considered useful in analysing design patterns of networks as well. Three-node patterns (triads) in metabolic networks have been studied to some extent producing classification of organisms based on triads, but their network placement was not analysed. We obtain the frequencies of all four-node subgraphs in a wide range of metabolic networks. We construct significance profiles of subgraphs and employ correlation analysis to compare and contrast these profiles, highlight- ing four-node motifs. We then compute specific centrality measures of nodes involved in each subgraph, namely betweenness centrality and closeness centrality. We observe that multiple four-node motifs exist in metabolic networks. The correlation analysis shows that the significance profiles of Eukaryotic networks are highly correlated across organisms, whereas those of the Prokaryotic networks are correlated less so. The centrality indices of nodes that participate in identified network motifs are shown to be quite high. The analysis provides a tool to pinpoint the transition between evolution stages of Prokaryotic and Eukaryotic metabolic networks.
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Cyclic preferential attachment in complex networks
(Elsevier, 2013-01-01) Kasthurirathna, D; Piraveenan, M
Preferential Attachment (PA), which was originally proposed in the Barabasi-Albert (BA) Model, has been widely ac- cepted as a network growth model which returns in scale-free networks. Preferential attachment in the BA model operates on the assumption that a node which has more links has a better likelihood to create new links. In this work, we expand the PA mechanism by treating it as a cyclic mechanism which is linked to both direct and indirect neighbours of a node. The assumption behind this extension is that the preference of nodes is influenced by their indirect neighbours as well. We show that traditional PA can be absorbed as a special case of this new growth model, which we name ‘cyclic preferential attachment’ (CPA). We also discuss the properties of simulated networks that were generated based on CPA. Finally, we compare and contrast the CPA based networks with the traditional PA based networks and several real-world networks of similar sizes and link-to-node ratios, and show that CPA offers more flexibility in modeling real world networks.
Open Access
Mobile based electricity billing system (MoBEBIS)
(International Journal of Scientific and Research Publication, 2013-04) Rathnayaka, M. R. M. S. B; Jayasinghe, I. D. S; EnitJayanth, S; Manamendra, S. I; Wimalaratne, G. M. A. S. C
Billing is a critical function of both the Electricity and the Water Boards towards getting a meter read. Meter reading, even though it looks simple, is far from simple and involves processes that can give various problems. Most problems, currently seen, result from the manual processes followed. Calculation errors, delays in system updating and fault tracking issues are the major problems that companies find difficult to find answers for. This paper suggests a mobile based system to collect, process and notify consumers about consumption. This system will be reliable, efficient and accurate to suit the requirements of these companies. The proposed solution uses evolving Mobile Technologies, over a solution which uses Mobile applications to handle a company’s day today work. The burden on the Meter Reader is lessened and other new features have also been introduced. Customer interaction with the company is improved and customers can easily view their current electricity usage using their mobile phones. However, the feasibility of such a project for a third world country like Sri Lanka, is a concern with tregard to the cost factor involved. The project demands substantial investments. Will the country be able to meet the costs involved? Yet, most of the problems related to Electricity Billing are addressed through this system and this might prove to be the best solution for specific companies to optimize services on a low budget
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Quantifying encircling behaviour in complex networks
(IEEE, 2013-04-16) Piraveenan, M; Uddin, S; Chung, K. S. K; Kasthurirathna, D
In this paper, we explore the effect of encircling behaviour on the topology of complex networks. We introduce the concept of topological encircling, which we define as an attacker making links to neighbours of a victim with the ultimate aim of undermining that victim. We introduce metrics to quantify topological encircling in complex networks, both at the network level and node pair (link) level. Using synthesized networks, we demonstrate that our measures are able to distinguish intentional topological encircling from preferential mixing. We discuss the potential utility of our measures and future research directions.
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Network robustness and topological characteristics in scale-free networks
(IEEE, 2013-04-16) Kasthurirathna, D; Piraveenan, M; Thedchanamoorthy, G
In this paper, we explore the relationship between the topological characteristics of a complex network and its robustness to sustained targeted attacks. Using synthesized scale-free networks, we look at a number of network measures, including rich club profiles, scale-free exponent, modularity, assortativity, average path length and clustering coefficient of a network, and how each of these influence the robustness of a scale-free network under targeted attacks. We consider sustained targeted attacks by order of node degree. We show that assortativity and average path length have a positive correlation with network robustness, whereas clustering coefficient has a negative correlation. We did not find any correlation between the modularity and robustness, scale-free exponent and robustness, or rich-club profiles and robustness. Our results highlight the importance of topological characteristics in influencing network robustness, and illustrate design strategies network designers can use to increase the robustness of scale-free networks under sustained targeted attacks.
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Applicability of Weyuker's properties using three complexity metrics
(IEEE, 2013-04-26) De Silva, D. I; Kodagoda, N
Although a number of complexity metrics have been proposed, only a few studies have been conducted to compare those proposed metrics to find the most effective and comprehensive metric. In general, to find the effectiveness and the comprehensiveness of a metric Weyuker's nine properties are used. However determining whether a complexity metric satisfies some theoretical framework is not enough to determine the effectiveness and comprehensiveness of that particular metric. Thus, this empirical study was conducted to find the effectiveness and comprehensiveness of three complexity metrics - McCabe's cyclomatic complexity, Halstead's software science and Shao and Wangs' cognitive functional size using the help of thirty software programmers with five or more years of working experience and thereby demonstrate the applicability of Weyuker's properties.
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Improvements for agile manifesto and make agile applicable for undergraduate research projects
(IEEE, 2013-04-26) Manamendra, M. A. S. C; Manathunga, K. N; Perera, K. H. D; Kodagoda, N
The paper describes the use of Agile software development methodology for undergraduate research projects. The students are required to do a project which spans for two academic semesters. The main objective is to see the appropriateness of Scrum for the undergraduate projects which is a widely used agile method at present in the software industry. The paper discusses main agile principles in the student's viewpoint to check how those are affected to meet the learning outcomes of the module by means of meeting the deadlines and getting constructive feedback from supervisors. The circulated survey results are analyzed thoroughly and discussed to prove the arguments made during the research time and the recommendations are provided to improve appropriateness hence required changes for the agile principles. Finally it is positive feedback from the students about using Agile for undergraduate projects to achieve the targets given to them.
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Improvements for agile manifesto and make agile applicable for undergraduate research projects
(IEEE, 2013-04-26) Manamendra, M. A. S. C; Manathunga, K; Perera, K. H. D; Kodagoda, N
The paper describes the use of Agile software development methodology for undergraduate research projects. The students are required to do a project which spans for two academic semesters. The main objective is to see the appropriateness of Scrum for the undergraduate projects which is a widely used agile method at present in the software industry. The paper discusses main agile principles in the student's viewpoint to check how those are affected to meet the learning outcomes of the module by means of meeting the deadlines and getting constructive feedback from supervisors. The circulated survey results are analyzed thoroughly and discussed to prove the arguments made during the research time and the recommendations are provided to improve appropriateness hence required changes for the agile principles. Finally it is positive feedback from the students about using Agile for undergraduate projects to achieve the targets given to them.
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The failure tolerance of mechatronic software systems to random and targeted attacks
(American Society of Mechanical Engineers, 2013-08-04) Kasthurirathna, D; Dong, A; Piraveenan, M; Tumer, I. Y
This paper describes a complex networks approach to study the failure tolerance of mechatronic software systems under various types of hardware and/or software failures. We produce synthetic system architectures based on evidence of modular and hierarchical modular product architectures and known motifs for the interconnection of physical components to software. The system architectures are then subject to various forms of attack. The attacks simulate failure of critical hardware or software. Four types of attack are investigated: degree centrality, betweenness centrality, closeness centrality and random attack. Failure tolerance of the system is measured by a ‘robustness coefficient’, a topological ‘size’ metric of the connectedness of the attacked network. We find that the betweenness centrality attack results in the most significant reduction in the robustness coefficient, confirming betweenness centrality, rather than the number of connections (i.e. degree), as the most conservative metric of component importance. A counter-intuitive finding is that “designed” system architectures, including a bus, ring, and star architecture, are not significantly more failure-tolerant than interconnections with no prescribed architecture, that is, a random architecture. Our research provides a data-driven approach to engineer the architecture of mechatronic software systems for failure tolerance.
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Standard deviations of degree differences as indicators of mixing patterns in complex networks
(IEEE, 2013-08-25) Thedchanamoorthy, G; Piraveenan, M; Kasthurirathna, D
Mixing patterns in social networks can give us important clues about the structure and functionality of these networks. In the past, a number of measures including variants of assortativity have been used to quantify degree mixing patterns of networks. In this paper, we are interested in observing the heterogeneity of the neighbourhood of nodes in networks. For this purpose, we use the standard deviation of degree differences between a node and its neighbours. We call this measure the `versatility' of a node. We apply this measure on synthetic and real world networks. We find that among real world networks three classes emerge -(i) Networks where the versatility converges to non-zero values with node degree (ii) Networks where the versatility converges to zero with node degree (iii) Networks where versatility does not converge with node degree. We find that there may be some correlation between this and network density, and the geographical / anatomical nature of networks may also be a factor. We also note that versatility could be applicable to any quantifiable network property, and not just node degree.
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Evolution of coordination in scale-free and small world networks under information diffusion constraints
(IEEE, 2013-08-25) Kasthurirathna, D; Piraveenan, M; Harre, M
We study evolution of coordination in social systems by simulating a coordination game in an ensemble of scale-free and small-world networks and comparing the results. We give particular emphasis to the role information about the pay-offs of neighbours plays in nodes adapting strategies, by limiting this information up to various levels. We find that if nodes have no chance to evolutionarily adapt, then non-coordination is a better strategy, however when nodes adapt based on information of the neighbour payoffs, coordination quickly emerges as the better strategy. We find phase transitions in number of coordinators with respect to the relative pay-off of coordination, and these phase transitions are sharper in small-world networks. We also find that when pay-off information of neighbours is limited, small-world networks are able to better cope with this limitation than scale-free networks. We observe that provincial hubs are the quickest to evolutionarily adapt strategies, in both scale-free and small world networks. Our findings confirm that evolutionary tendencies of coordination heavily depend on network topology.
Open Access
Node assortativity in complex networks: An alternative approach
(Elsevier, 2014-01-01) Thedchanamoorthy, G; Piraveenan, M; Kasthuriratna, D; Senanayake, U
Assortativity quantifies the tendency of nodes being connected to similar nodes in a complex network. Degree Assortativity can be quantified as a Pearson correlation. However, it is insufficient to explain assortative or disassortative tendencies of individual nodes or links, which may be contrary to the overall tendency of the network. A number of ‘local’ assortativity measures have been proposed to address this. In this paper we define and analyse an alternative formulation for node assortativity, primarily for undirected networks. The alternative approach is justified by some inherent shortcomings of existing local measures of assortativity. Using this approach, we show that most real world scale-free networks have disassortative hubs, though we can synthesise model networks which have assortative hubs. Highlighting the relationship between assortativity of the hubs and network robustness, we show that real world networks do display assortative hubs in some instances, particularly when high robustness to targeted attacks is a necessity.