Computer Engineering / Bilgisayar Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/10
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Article Citation - WoS: 10Citation - Scopus: 26Mobile Join Operators for Restricted Sources(Hindawi Publishing Corporation, 2005) Özakar, Belgin; Morvan, Franck; Hameurlain, AbdelkaderWe consider the problem of query execution when there is limited access to the relations, i.e. when binding patterns require values to be specified in order to get data from the relation. This problem is common in virtual data integration systems where there are heterogeneous sources with various restricted access patterns and query capabilities. Another problem is the lack of the statistical information about the sources and occurrence of unpredictable events. We introduce two mobile join operators, MDJoin and SMDJoin which are designed for restricted sources and implemented using ‘mobile agents’ in order to benefit from their autonomous and reactive characteristics. Mobile operators of restricted sources are capable to deal with restricted sources and react to the variations between the compile-time estimations and run-time computations of data during query execution. The difference between the two new query operators lies in their level of adaptation ability to the execution environment. Performance results show that mobile agent-based approach at operator level can lead to a significant reduction in response time with restricted sources.Conference Object Citation - WoS: 17Citation - Scopus: 30A Performance and Profit Oriented Data Replication Strategy for Cloud Systems(Institute of Electrical and Electronics Engineers Inc., 2017) Tos, Uras; Mokadem, Riad; Hameurlain, Abdelkader; Ayav, Tolga; Bora, ŞebnemIn today's world, tenants of cloud systems expect timely responses to queries that process ever-increasing sizes of data. However, most cloud providers offer their services without any performance guarantees to their tenants. In this paper we propose a data replication strategy that aims to satisfy performance guarantees for the tenant while ensuring profitability of the cloud provider. Our strategy estimates the response time of the queries, as well as the expenditures that affect the profitability of the cloud provider. The decision of whether to perform replication is determined by the fulfillment of these two criteria. Validity of the proposed strategy is provided by means of a simulation study.Conference Object Citation - Scopus: 2Resource Allocation Algorithm for a Relational Join Operator in Grid Systems(Association for Computing Machinery (ACM), 2012) Çokuslu, Deniz; Hameurlain, Abdelkader; Erciyeş, Kayhan; Morvan, FranckGrid systems become very popular during the last decade because of their rapidly increasing computational capabilities. On the other hand, the advances on different domains cause enormous increase in the scale of the manipulated data. This issue augments the importance of distributed query processing and causes researchers to port their underlying environment onto the grid systems. However the dynamicity, heterogeneity and large scale characteristics of grid systems pose new problems for the distributed query processing domain. Resource allocation for query processing in grid systems is one of these problems, which attracts many researchers' attention. In this paper, we propose a new resource allocation algorithm for one relational join operator in a query considering characteristics of the grid systems. We provide theoretical analyses of the proposed algorithm and we consolidate analyses with the simulations. Copyright © 2012 ACM.Conference Object Citation - Scopus: 3Grid Resource Discovery Based on Web Services(Institute of Electrical and Electronics Engineers Inc., 2009) Çokuslu, Deniz; Hameurlain, Abdelkader; Erciyeş, KayhanThe size of grid systems has increased substantially in the last decades. Resource discovery in grid systems is a fundamental task which provides searching and locating necessary resources for a given process. Various different approaches are proposed in literature for this problem. Grid resource discovery using web services is an important approach which has resulted in many tools to become de facto standards of today's grid resource management. In this paper, we propose a survey of recent grid resource discovery studies based on web services. We provide synthesis, analysis and evaluation of these studies by classification. We also give a comparative study of different classes proposed.Conference Object Citation - WoS: 4Citation - Scopus: 6Robust Placement of Mobile Relational Operators for Large Scale Distributed Query Optimization(Institute of Electrical and Electronics Engineers Inc., 2007) Ergenç, Belgin; Morvan, Franck; Hameurlain, AbdelkaderThis paper presents a compile-time placement method of mobile relational operators MROs in a large scale environment. MROs are self adaptive to changing runtime conditions by deciding their execution place if they discover compile-time estimation errors. Proposed placement methods tend to have a main drawback with MROs running over a large scale environment: their focus is on finding optimal performance depending on single-point estimation at compile-time, instead of optimal performance over an estimation interval. We propose: (i) to determine the migration space of a MRO including the sites on which the MRO is allowed to migrate during its execution, and (ii) to find the robust site which will allow acceptable response time in an estimation interval. Performance study shows that, with a risk of loosing around 6% in response time, it is possible to gain up to 300% with the proposed robust placement.