In recent years, recommender systems have become an important part of various applications, supporting both customers and providers in their decision-making processes. However, these systems still must overcome limitations that reduce their performance, like recommendations' overspecialization, cold start, and difficulties when items with unequal probability distribution appear or recommendations for sets of items are asked. A novel approach, addressing the above issues through a case-based recommendation methodology, is presented here. The scope of the presented approach is to generate meaningful recommendations based on items' co-occurring patterns and to provide more insight into customers' buying habits. In contrast to current recommendation techniques that recommend items based on users' ratings or history, and to most case-based item recommenders that evaluate items' similarities, the implemented recommender uses a hierarchical model for the items and searches for similar sets of items, in order to recommend those that are most likely to satisfy a user.
Anagnostopoulos, V.; Moulos, V.; Menychtas, A.; Varvarigou, D.; Gatzioura, A.; Díaz, M.; Ibañez, L. Panhellenic Conference on Informatics p. 1-6 DOI: 10.1145/2645791.2645844 Data de presentació: 2014-10 Presentació treball a congrés
Cloud computing aims to realize the vision of computing as a utility provided in an economically viable manner. A necessary condition for its success as a business solution is the existence of proper software tools for the development and provision of applications for this highly dynamic ecosystem. In this paper we focus on the tools providing PaaS (Platform-As-A-Service) functionalities and more specific we propose a new middleware architecture that could allow the creation of elastic applications with the scalability of the application transparently embedded in the middleware. Departing from legacy considerations, we embrace the latest trends in scalable distributed software design as well as concepts from SOAs (Service Oriented Architectures) and agent-based computing with the goal to provide a futureproof platform in technical and business sense. Central to our approach is the tackling of the scalability and pricing problems in order to reliably further the adoption of the pay as you go model. Moreover we put special emphasis on a formal definition of scalability rules and on structuring our middleware along these lines.
Gatzioura, A.; Menychtas, A.; Moulos, V.; Varvarigou, T. International Conference on Parallel and Distributed Processing Techniques and Applications p. 446-472 DOI: 10.1109/ISPA.2012.68 Presentació treball a congrés
Cloud computing has changed considerably the architecture of modern IT systems introducing new design principles based on the notion of the service as main building unit. Decoupling the service offering from the underlying infrastructure, cloud computing allows for more efficient management of the required resources which in business level is translated into higher flexibility and increased profit. To this end, Clouds are not only an innovative technological environment but also a beneficial market for all the involved stakeholders. This market expands continuously and new service aggregations, customizations and business models are offered in order to cover the needs of all end-users. However, even in this new business ecosystem, the question still remains: “Which offering should I buy”? In this paper we present an approach for incorporating business intelligence in cloud marketplaces through a mechanism for answering this question based on the individual requirements and use profile of each particular cloud customer.
Menychtas, A.; Gatzioura, A.; Varvarigou, T. IEEE International Conference on Cloud Computing Technology and Science p. 462-469 DOI: doi: 10.1109/CloudCom.2011.68 Data de presentació: 2011-11-29 Presentació treball a congrés
Nowadays cloud computing can be considered as a key element of modern ICT systems, changing the technological and architectural aspects that these systems are designed and managed. The number and variety of applications, exploiting the advantages of this new computing paradigm, is increasing, emerging a new market of services and resources. Modern applications, from enterprise software to mobile and social networking apps are adapted and become available through the Cloud, allowing wider adoption and advanced functionality. Besides the numerous technical and technological advancements, cloud computing also leverages new business models and value networks. To this direction more entities are involved in the service delivery process and marketplaces are created to ease the development of applications through reusability and aggregation of services and resources. In this paper we present an innovative mechanism for the resolution of the customers' requirements which enhances the process of selecting cloud services from the business point of view.