The field of Statistics is a conceptually rich domain where information is complex, huge in volum... more The field of Statistics is a conceptually rich domain where information is complex, huge in volume, and highly valuable and critical for Governmental institutes. The daily production of statistical information increases exponent-tially worldwide, making the processing of all this information a very difficult and time-consuming task. Therefore, efficient search, filtering and browsing techniques are needed to access and process statistical data an effective way. We present semantically enhanced search approach to enhance e-Government searching services. We evaluate our proposals on the case of Intrastat, that is the method of collecting information and producing statistics on the export and import of goods between Member States of the European Union (EU), providing added-value web search services. We employ Semantic Web technologies to create an intelligent search engine based on modeling the systems' electronic catalogue using the OWL ontology language, combined with AJAX techni...
BibTeX-Entry of (P. Adamopoulou, E. Sakkopoulos, A. Tsakalidis, M. Lytras) Web Service Selection ... more BibTeX-Entry of (P. Adamopoulou, E. Sakkopoulos, A. Tsakalidis, M. Lytras) Web Service Selection based on QoS Knowledge Management. @String{j-jucs = "Journal of Universal Computer Science"} @Article{Adamopoulou ...
In recent technologies like IoT (Internet of Things) and Web 2.0, a critical problem arises with ... more In recent technologies like IoT (Internet of Things) and Web 2.0, a critical problem arises with respect to storing and processing the large amount of collected data. In this paper we develop and evaluate distributed infrastructures for storing and processing large amount of such data. We present a distributed framework that supports customized deployment of a variety of indexing engines over million-node overlays. The proposed framework provides the appropriate integrated set of tools that allows applications processing large amount of data, to evaluate and test the performance of various application protocols for very large scale deployments (multi million nodes-billions of keys). The key aim is to provide the appropriate environment that contributes in taking decisions regarding the choice of the protocol in storage P2P systems for a variety of big data applications. Using lightweight and efficient collection mechanisms, our system enables * A very preliminary version of this work was presented in ACM SAC'12, pp.853-858, March 25-29, 2012, Riva del Garda, Italy. This work was partially supported by Thales Project entitled "Cloud9: A multidisciplinary, holistic approach to internet-scale cloud computing". For more details see the following URL: https://sites.google.com/site/thaliscloud9/home D-P2P-Sim + 2 real-time registration of multiple measures, integrating support for real-life parameters such as node failure models and recovery strategies. Experiments have been performed at the PlanetLab network and at a typical research laboratory in order to verify scalability and show maximum reusability of our setup. D-P2P-Sim+ framework is publicly available at
2011 IEEE Symposium on Computers and Communications (ISCC), 2011
The explosive growth in the size and use of the World Wide Web continuously creates new great cha... more The explosive growth in the size and use of the World Wide Web continuously creates new great challenges and needs. One such need is dealing with click fraud, which aims at increasing clicks on certain ads and thus the profit of the websites which display them. In this work, we extend the concept of click fraud and redefine it as
We present the design and implementation of an adaptive user model in a web-based virtual univers... more We present the design and implementation of an adaptive user model in a web-based virtual university learning environment. It includes techniques that provide personalization features to the educational topic and the exchanging information. In this way it customizes the educational process, served by any virtual university to the personal characteristics of the user. Its distinctive functionality is that encompasses combined adaptation between educational material and wellknown communication facilities. In fact the user model consists of different layers that make the environment personalized in two axes. Firstly adaptation is performed separately per activity (member of the profile's higher level) and subsequently knowledge of the different levels is shared through the common lower level and provides further personalization in a more global sense. Personalization obsolescence is also included in the user model in order to prohibit outdated adaptation or intelligence to keep loading the user interface. Furthermore curriculum sequencing provides guidance to the user's learning procedure. Most interesting educational pages for the users-based on their profile-are selectively delivered to them, according to the collaborative filtering method. Finally special care has been taken for the categorization of incoming data streams handled by content and property based filtering.
2013 IEEE 14th International Conference on Mobile Data Management, 2013
ABSTRACT Positioning capabilities offered in modern mobile devices enable usage of location-based... more ABSTRACT Positioning capabilities offered in modern mobile devices enable usage of location-based services. Privacy and security is of great importance for related applications. We present a framework that allows conducting research on anonymity techniques in a real-life environment using smartphones. The proposed solution also includes logging mechanisms that facilitate positioning research dataset development in open format. To present the capabilities of the solution, we deliver the concept of K-anonymity to protect mobile users that issue queries to location-based services. Experimental evaluation of the solution includes development of real-life logging dataset using smartphones by volunteers. Different flavours of anonymity algorithms are easy to be included and tested. The solution has received encouraging feedback and successfully assists the researchers of location based services to experiment, validate and develop their techniques in real life environment.
Inclusion of Information and Communication Technologies (ICTs) and multimedia in a museum can res... more Inclusion of Information and Communication Technologies (ICTs) and multimedia in a museum can result in a functional upgrade of the visitor experience in an exhibition. The added value of ICTs includes promoting the enhancement of educational, research, and entertainment purposes towards which a museum has already been designed. To better understand the potential role of ICTs in museums, the authors introduce an XML-based customizable system. In this chapter, they present an XML-based customizable multimedia solution for museums and exhibitions. The proposed approach serves multimedia content solutions for the assistance of visitors and researchers. A modular approach is adopted in order to provide a User Interface abstraction and operation-business logic isolation from the data. The key advantage of the proposed solution is the separation of concerns for User Interface, business logic, and data retrieval. The proposed solution allows the dynamic XML-based customization of museum mu...
Proceedings of the International Conference on Management of Emergent Digital EcoSystems - MEDES '09, 2009
In this paper we discuss the integration of QoS-aware search and personalization algorithms in or... more In this paper we discuss the integration of QoS-aware search and personalization algorithms in order to discover effectual Web Services for the case of mobile web users. We present a number of novel ranking algorithms specially designed for mobile web architectures. To validate and evaluate the proposed algorithms we developed a fully working prototype for mobile-PDA devices. The prototype enables PDA users to access electronic shops and to retrieve information about their products, while going shopping. Comparative experimental results have shown encouraging results that prove m-scroutz to be effective.
2005 IEEE International Conference on e-Technology, e-Commerce and e-Service
Generic web search is designed to serve all users, independent of the individual needs and withou... more Generic web search is designed to serve all users, independent of the individual needs and without any adaptation to personal requirements. We propose a novel technique 1 that performs post-categorization to the results of popular search engines at the client's side. A user profile is built based on user's choices from a category hierarchy (explicitly given requirements) and user's search history (implicitly logged choices). Caching is utilized in order to provide improved responses. An experimental prototype has been implemented based on results coming from a popular search engine. The experimental results indicate strongly that the proposed mechanism is both effective and efficient.
Special interest tracks and posters of the 14th international conference on World Wide Web - WWW '05, 2005
This work aims a twofold contribution: it presents a software to analyse logfiles and visualize p... more This work aims a twofold contribution: it presents a software to analyse logfiles and visualize popular web hot spots and, additionally, presents an algorithm to use this information in order to identify subsets of the website that display large access patterns. Such information is extremely valuable to the site maintainer, since it indicates points that may need content intervention or/and site graph restructuring. Experimental validation verified that the visualization tool, when coupled with algorithms that infer frequent traversal patterns, is both effective in indicating popular hot spots and efficient in doing so by using graph-based representations of popular traversals.
Proceedings of the 2006 ACM symposium on Applied computing - SAC '06, 2006
In this work we present techniques and tools that enable effective reverse engineering procedures... more In this work we present techniques and tools that enable effective reverse engineering procedures for web applications that were developed using the promising ASP.NET technology. We deal with model-driven development in its reverse aspect by implementing reverse engineering methods. Our implemented methods model web applications using a well-known, web oriented and robust language, namely WebML. This is, to the authors'
The paper is concerned with the effective and efficient processing of temporal selection queries ... more The paper is concerned with the effective and efficient processing of temporal selection queries in Video Database and generally Temporal Database Management Systems (TDBMS). Based on both general spatio-temporal retrieval framework ((3)) and recent versions of internal-external Priority Search Trees, we present an optimal in time and space algorithm for the problem that answers certain temporal content queries invoking video functions. We prove the optimality by giving both a new theoretical comparison method based on microanalysis and its experimental verification. 1. Overview
In this paper, we present data management issues faced during the design and development of an op... more In this paper, we present data management issues faced during the design and development of an open distance learning system for the University of Patras, Greece. In order to handle data eciently, as required in a web tele-training application, for each type of information maintained, dierent strategies must be deployed according to their behaviour and structure. The diversity and complexity of data, the network aspect of the application and web de®ciencies impose an architecture design incorporating a plethora of technologies and tools that must be integrated in such a fashion that they eciently organise these data preserving their relationships. This presents a software engineering challenge requiring coherence of solutions at all levels: structures, consistency, security, models, and protocols. The paper presents the data components of an open and distance learning (ODL) system that access the information stored in a database and the ®le system, their underlying technology, their interaction with the network services, and features regarding the ways they address issues faced in an open vendorindependent distance learning environment and outlines the system's overall architecture. In addition, this paper presents the architecture, the design and the services of a network-based information system that supports open and distance learning activities. The open and distance learning information system (ODLIS) oers synchronous and asynchronous distance learning and management of information system (MIS) services to support the educational procedure. The ODLIS is a web-based application, which runs over the Internet using real time protocols.
... surfing behavior. Moreover, a design research approach combining behavior and engineering tec... more ... surfing behavior. Moreover, a design research approach combining behavior and engineering techniques is proposed to better support user modeling in personalized mobile advertising applications (Xu et al., 2008). Even in ...
Service Oriented Computing and its most famous implementation technology Web Services (WS) are be... more Service Oriented Computing and its most famous implementation technology Web Services (WS) are becoming an important enabler of networked business models. Discovery mechanisms are a critical factor to the overall utility of Web Services. So far, discovery mechanisms based on the UDDI standard rely on many centralized and area-specific directories, which poses information stress problems such as performance bottlenecks and
Attempts have been made concerning the search and finding of a Web Service based on keywords and ... more Attempts have been made concerning the search and finding of a Web Service based on keywords and descriptions. However, no work has been done concerning the efficient selection of the appropriate Web Service instance in terms of quality and performance factors at the moment of the Web Service consumption attempt. Such factors may include execution time and response time. The proposed approach adaptively selects the most efficient WS among possible different alternatives with real-time, optimized and countable factors-parameters. Implementation issues and case study experiments are presented along with the corresponding results. Additionally, an optimal selection algorithm for series of Web Services requests is proposed. Finally, conclusions and future steps are discussed.
The field of Statistics is a conceptually rich domain where information is complex, huge in volum... more The field of Statistics is a conceptually rich domain where information is complex, huge in volume, and highly valuable and critical for Governmental institutes. The daily production of statistical information increases exponent-tially worldwide, making the processing of all this information a very difficult and time-consuming task. Therefore, efficient search, filtering and browsing techniques are needed to access and process statistical data an effective way. We present semantically enhanced search approach to enhance e-Government searching services. We evaluate our proposals on the case of Intrastat, that is the method of collecting information and producing statistics on the export and import of goods between Member States of the European Union (EU), providing added-value web search services. We employ Semantic Web technologies to create an intelligent search engine based on modeling the systems' electronic catalogue using the OWL ontology language, combined with AJAX techni...
BibTeX-Entry of (P. Adamopoulou, E. Sakkopoulos, A. Tsakalidis, M. Lytras) Web Service Selection ... more BibTeX-Entry of (P. Adamopoulou, E. Sakkopoulos, A. Tsakalidis, M. Lytras) Web Service Selection based on QoS Knowledge Management. @String{j-jucs = "Journal of Universal Computer Science"} @Article{Adamopoulou ...
In recent technologies like IoT (Internet of Things) and Web 2.0, a critical problem arises with ... more In recent technologies like IoT (Internet of Things) and Web 2.0, a critical problem arises with respect to storing and processing the large amount of collected data. In this paper we develop and evaluate distributed infrastructures for storing and processing large amount of such data. We present a distributed framework that supports customized deployment of a variety of indexing engines over million-node overlays. The proposed framework provides the appropriate integrated set of tools that allows applications processing large amount of data, to evaluate and test the performance of various application protocols for very large scale deployments (multi million nodes-billions of keys). The key aim is to provide the appropriate environment that contributes in taking decisions regarding the choice of the protocol in storage P2P systems for a variety of big data applications. Using lightweight and efficient collection mechanisms, our system enables * A very preliminary version of this work was presented in ACM SAC'12, pp.853-858, March 25-29, 2012, Riva del Garda, Italy. This work was partially supported by Thales Project entitled "Cloud9: A multidisciplinary, holistic approach to internet-scale cloud computing". For more details see the following URL: https://sites.google.com/site/thaliscloud9/home D-P2P-Sim + 2 real-time registration of multiple measures, integrating support for real-life parameters such as node failure models and recovery strategies. Experiments have been performed at the PlanetLab network and at a typical research laboratory in order to verify scalability and show maximum reusability of our setup. D-P2P-Sim+ framework is publicly available at
2011 IEEE Symposium on Computers and Communications (ISCC), 2011
The explosive growth in the size and use of the World Wide Web continuously creates new great cha... more The explosive growth in the size and use of the World Wide Web continuously creates new great challenges and needs. One such need is dealing with click fraud, which aims at increasing clicks on certain ads and thus the profit of the websites which display them. In this work, we extend the concept of click fraud and redefine it as
We present the design and implementation of an adaptive user model in a web-based virtual univers... more We present the design and implementation of an adaptive user model in a web-based virtual university learning environment. It includes techniques that provide personalization features to the educational topic and the exchanging information. In this way it customizes the educational process, served by any virtual university to the personal characteristics of the user. Its distinctive functionality is that encompasses combined adaptation between educational material and wellknown communication facilities. In fact the user model consists of different layers that make the environment personalized in two axes. Firstly adaptation is performed separately per activity (member of the profile's higher level) and subsequently knowledge of the different levels is shared through the common lower level and provides further personalization in a more global sense. Personalization obsolescence is also included in the user model in order to prohibit outdated adaptation or intelligence to keep loading the user interface. Furthermore curriculum sequencing provides guidance to the user's learning procedure. Most interesting educational pages for the users-based on their profile-are selectively delivered to them, according to the collaborative filtering method. Finally special care has been taken for the categorization of incoming data streams handled by content and property based filtering.
2013 IEEE 14th International Conference on Mobile Data Management, 2013
ABSTRACT Positioning capabilities offered in modern mobile devices enable usage of location-based... more ABSTRACT Positioning capabilities offered in modern mobile devices enable usage of location-based services. Privacy and security is of great importance for related applications. We present a framework that allows conducting research on anonymity techniques in a real-life environment using smartphones. The proposed solution also includes logging mechanisms that facilitate positioning research dataset development in open format. To present the capabilities of the solution, we deliver the concept of K-anonymity to protect mobile users that issue queries to location-based services. Experimental evaluation of the solution includes development of real-life logging dataset using smartphones by volunteers. Different flavours of anonymity algorithms are easy to be included and tested. The solution has received encouraging feedback and successfully assists the researchers of location based services to experiment, validate and develop their techniques in real life environment.
Inclusion of Information and Communication Technologies (ICTs) and multimedia in a museum can res... more Inclusion of Information and Communication Technologies (ICTs) and multimedia in a museum can result in a functional upgrade of the visitor experience in an exhibition. The added value of ICTs includes promoting the enhancement of educational, research, and entertainment purposes towards which a museum has already been designed. To better understand the potential role of ICTs in museums, the authors introduce an XML-based customizable system. In this chapter, they present an XML-based customizable multimedia solution for museums and exhibitions. The proposed approach serves multimedia content solutions for the assistance of visitors and researchers. A modular approach is adopted in order to provide a User Interface abstraction and operation-business logic isolation from the data. The key advantage of the proposed solution is the separation of concerns for User Interface, business logic, and data retrieval. The proposed solution allows the dynamic XML-based customization of museum mu...
Proceedings of the International Conference on Management of Emergent Digital EcoSystems - MEDES '09, 2009
In this paper we discuss the integration of QoS-aware search and personalization algorithms in or... more In this paper we discuss the integration of QoS-aware search and personalization algorithms in order to discover effectual Web Services for the case of mobile web users. We present a number of novel ranking algorithms specially designed for mobile web architectures. To validate and evaluate the proposed algorithms we developed a fully working prototype for mobile-PDA devices. The prototype enables PDA users to access electronic shops and to retrieve information about their products, while going shopping. Comparative experimental results have shown encouraging results that prove m-scroutz to be effective.
2005 IEEE International Conference on e-Technology, e-Commerce and e-Service
Generic web search is designed to serve all users, independent of the individual needs and withou... more Generic web search is designed to serve all users, independent of the individual needs and without any adaptation to personal requirements. We propose a novel technique 1 that performs post-categorization to the results of popular search engines at the client's side. A user profile is built based on user's choices from a category hierarchy (explicitly given requirements) and user's search history (implicitly logged choices). Caching is utilized in order to provide improved responses. An experimental prototype has been implemented based on results coming from a popular search engine. The experimental results indicate strongly that the proposed mechanism is both effective and efficient.
Special interest tracks and posters of the 14th international conference on World Wide Web - WWW '05, 2005
This work aims a twofold contribution: it presents a software to analyse logfiles and visualize p... more This work aims a twofold contribution: it presents a software to analyse logfiles and visualize popular web hot spots and, additionally, presents an algorithm to use this information in order to identify subsets of the website that display large access patterns. Such information is extremely valuable to the site maintainer, since it indicates points that may need content intervention or/and site graph restructuring. Experimental validation verified that the visualization tool, when coupled with algorithms that infer frequent traversal patterns, is both effective in indicating popular hot spots and efficient in doing so by using graph-based representations of popular traversals.
Proceedings of the 2006 ACM symposium on Applied computing - SAC '06, 2006
In this work we present techniques and tools that enable effective reverse engineering procedures... more In this work we present techniques and tools that enable effective reverse engineering procedures for web applications that were developed using the promising ASP.NET technology. We deal with model-driven development in its reverse aspect by implementing reverse engineering methods. Our implemented methods model web applications using a well-known, web oriented and robust language, namely WebML. This is, to the authors'
The paper is concerned with the effective and efficient processing of temporal selection queries ... more The paper is concerned with the effective and efficient processing of temporal selection queries in Video Database and generally Temporal Database Management Systems (TDBMS). Based on both general spatio-temporal retrieval framework ((3)) and recent versions of internal-external Priority Search Trees, we present an optimal in time and space algorithm for the problem that answers certain temporal content queries invoking video functions. We prove the optimality by giving both a new theoretical comparison method based on microanalysis and its experimental verification. 1. Overview
In this paper, we present data management issues faced during the design and development of an op... more In this paper, we present data management issues faced during the design and development of an open distance learning system for the University of Patras, Greece. In order to handle data eciently, as required in a web tele-training application, for each type of information maintained, dierent strategies must be deployed according to their behaviour and structure. The diversity and complexity of data, the network aspect of the application and web de®ciencies impose an architecture design incorporating a plethora of technologies and tools that must be integrated in such a fashion that they eciently organise these data preserving their relationships. This presents a software engineering challenge requiring coherence of solutions at all levels: structures, consistency, security, models, and protocols. The paper presents the data components of an open and distance learning (ODL) system that access the information stored in a database and the ®le system, their underlying technology, their interaction with the network services, and features regarding the ways they address issues faced in an open vendorindependent distance learning environment and outlines the system's overall architecture. In addition, this paper presents the architecture, the design and the services of a network-based information system that supports open and distance learning activities. The open and distance learning information system (ODLIS) oers synchronous and asynchronous distance learning and management of information system (MIS) services to support the educational procedure. The ODLIS is a web-based application, which runs over the Internet using real time protocols.
... surfing behavior. Moreover, a design research approach combining behavior and engineering tec... more ... surfing behavior. Moreover, a design research approach combining behavior and engineering techniques is proposed to better support user modeling in personalized mobile advertising applications (Xu et al., 2008). Even in ...
Service Oriented Computing and its most famous implementation technology Web Services (WS) are be... more Service Oriented Computing and its most famous implementation technology Web Services (WS) are becoming an important enabler of networked business models. Discovery mechanisms are a critical factor to the overall utility of Web Services. So far, discovery mechanisms based on the UDDI standard rely on many centralized and area-specific directories, which poses information stress problems such as performance bottlenecks and
Attempts have been made concerning the search and finding of a Web Service based on keywords and ... more Attempts have been made concerning the search and finding of a Web Service based on keywords and descriptions. However, no work has been done concerning the efficient selection of the appropriate Web Service instance in terms of quality and performance factors at the moment of the Web Service consumption attempt. Such factors may include execution time and response time. The proposed approach adaptively selects the most efficient WS among possible different alternatives with real-time, optimized and countable factors-parameters. Implementation issues and case study experiments are presented along with the corresponding results. Additionally, an optimal selection algorithm for series of Web Services requests is proposed. Finally, conclusions and future steps are discussed.
Uploads
Papers by e. sakkopoulos