@conference {margaris2016a,
	title = {Improving QoS Delivered by WS-BPEL Scenario Adaptation through Service Execution Parallelization},
	booktitle = {Proceedings of the 31st Annual ACM Symposium on Applied Computing},
	year = {2016},
	pages = {1590-1596},
	publisher = {ACM},
	organization = {ACM},
	abstract = {WS-BPEL scenario execution adaptation has been proposed by researchers as a response to the need of users to tailor the WS-BPEL scenario execution to their individual preferences; these preferences are typically expressed through Quality of Service (QoS) policies, which the adaptation mechanism considers in order to select the services that will ultimately be invoked to realize the desired business process. In this paper, we study the potential to parallelize the execution of the WS-BPEL scenario in order to minimize its response time and/or achieving higher scores in the other qualitative dimensions, such as cost, reliability, etc., at the same time. We also describe, develop and validate a parallelization algorithm for realizing the proposed enhancements.},
	doi = {10.1145/2851613.2851805},
	url = {https://dl.acm.org/citation.cfm?id=2851805},
	author = {Dionisis Margaris and Costas Vassilakis and P. Georgiadis}
}
@article {margaris14a,
	title = {An integrated framework for adapting WS-BPEL scenario execution using QoS and collaborative filtering techniques},
	journal = {Science of Computer Programming},
	volume = {98},
	year = {2015},
	pages = {707{\textendash}734},
	abstract = {In this paper, we present a framework which incorporates runtime adaptation for BPEL scenarios. The adaptation is based on (a) the quality of service parameters of available services, allowing for tailoring their execution to the diverse needs of individual users and (b)collaborative filtering techniques, allowing clients to further refine the adaptation process by considering service selections made by other clients, in the context of the same business processes. The proposed framework also caters maintaining the transactional semantics that invocations to multiple services offered by the same provider may bear.},
	doi = {10.1016/j.scico.2014.10.007},
	url = {http://www.sciencedirect.com/science/article/pii/S0167642314004778},
	author = {Dionisis Margaris and Costas Vassilakis and P. Georgiadis}
}
@conference {Margaris2013SAC,
	title = {An integrated framework for QoS-based adaptation and exception resolution in WS-BPEL scenarios},
	booktitle = {Proceedings of the 28th Annual ACM Symposium on Applied Computing - SAC \textquotesingle13},
	year = {2013},
	month = {3},
	publisher = {ACM Press},
	organization = {ACM Press},
	abstract = {In this paper, we present a framework which incorporates runtime quality of service-based adaptation for BPEL scenarios, allowing for tailoring their execution to the diverse needs of individual users. The proposed framework also caters for automatically resolving system-level exceptions, such as machine outages or network partitionings, while both scenario execution adaptation and exception resolution maintain the transactional semantics that invocations to multiple services offered by the same provider may bear.},
	doi = {10.1145/2480362.2480714},
	author = {Dionisis Margaris and Costas Vassilakis and P. Georgiadis}
}
@article {Kareliotis2009284,
	title = {IQoS-aware exception resolution for BPEL processes: A middleware-based framework and performance evaluation},
	journal = {International Journal of Web and Grid Services},
	volume = {5},
	number = {3},
	year = {2009},
	note = {cited By (since 1996) 0},
	pages = {284-320},
	abstract = {Web Services Business Process Execution Language (WS-BPEL) is widely used nowadays for specifying and executing composite business processes. During the execution, however, of such business processes, a number of faults stemming from the nature of SOA may occur. The WS-BPEL scenario designer must therefore use the provisions offered by WS-BPEL to catch these exceptions and resolve them. The system fault handler specification, however, is an additional task for the WS scenario designer, while the presence of such handlers within the scenario necessitates extra maintenance activities. In this paper, we propose a middleware-based framework for system exception resolution, which undertakes the tasks of failure interception, discovery of alternative services and their invocation. The process of selecting the alternative services can be driven by process consumer-specified Quality of Service (QoS) policy. Moreover, the middleware arranges for bridging syntactic differences between the originally invoked services and functionally equivalent replacements to it, by employing XSLT-based transformations. The middleware is deployed and maintained independently of the WS-BPEL scenarios, thus removing the need for specifying and maintaining system fault handlers within the scenarios. We also present performance measures, establishing that the overhead imposed by the addition of the proposed middleware layer is minimal. Copyright Β{\textcopyright} 2009, Inderscience Publishers.},
	keywords = {Ad hoc networks, BPEL process, Exception handling, Exception resolution, Middleware, Performance metrics, QoS, Quality control, Quality of service, Scalability, Telecommunication services, Web services},
	doi = {10.1504/IJWGS.2009.028346},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-70349462474\&partnerID=40\&md5=4511b42fde076617cd6ac0139e3f588d},
	author = {Christos Kareliotis and Costas Vassilakis and S. Rouvas and P. Georgiadis}
}
@article {DBLP:journals/eg/VassilakisLRG04,
	title = {Integrating e-government public transactional services into public authority workflows},
	journal = {Electronic Government},
	volume = {1},
	number = {1},
	year = {2004},
	pages = {49-60},
	abstract = {Documents submitted by citizens through electronic services deployed in the context of e-Government must usually undergo processing by some organisational information system, in order to complete the citizens? requests and for the reply to be returned to the citizen. The integration, however, of the e-service delivery platform and the organisational information system is often hindered for a number of reasons, including security considerations, platform diversity or idiosyncrasies of legacy information systems. In this paper we present a generic method for providing seamless communication between the two platforms, enabling the full integration of documents submitted through electronic services into the organisational workflow, leveraging thus the quality of services offered to the citizens and facilitating e-service development and operation.},
	doi = {10.1504/EG.2004.004136},
	author = {Costas Vassilakis and Giorgos Lepouras and S. Rouvas and P. Georgiadis}
}
@conference {DBLP:conf/caise/VassilakisLRG03,
	title = {Improving e-Form Layout Through Analysis of Form Semantics and Validation Checks},
	booktitle = {CAiSE Short Paper Proceedings},
	year = {2003},
	month = {6},
	abstract = {Transaction services offered by public authorities vary from simple forms with few fields to multi-form compound documents with hundreds of input areas. In the latter case, field placement within forms is of particular importance for facilitating the filling and error correction processes. In this paper we present an approach to improving the form layout by exploiting validation checks that are usually associated with electronic forms, as well as semantic information that may be attached to form fields by designers.},
	url = {http://ceur-ws.org/Vol-74/files/FORUM_38.pdf},
	author = {Costas Vassilakis and Giorgos Lepouras and S. Rouvas and P. Georgiadis}
}
@article {Vassilakis1998335,
	title = {Implementation of transaction and concurrency control support in a temporal DBMS},
	journal = {Information Systems},
	volume = {23},
	number = {5},
	year = {1998},
	note = {cited By (since 1996) 2},
	pages = {335{\textendash}350},
	abstract = {Transactions and concurrency control are significant features in database systems, facilitating functions both at user and system level. However, the support of these features in a temporal DBMS has not yet received adequate research attention. In this paper, we describe the techniques developed in order to support transaction and concurrency control in a temporal DBMS that was implemented as an additional layer to a commercial DBMS. The proposed techniques make direct use of the transaction mechanisms of the DBMS. In addition, they overcome a number of limitations such as automatic commit points, lock release and log size increment, which are imposed by the underlying DBMS. Our measurements have shown that the overhead introduced by these techniques is negligible, less than 1\% in all cases. The approach undertaken is of general interest, it can also be applied to non-temporal DBMS extensions. Copyright Β{\textcopyright} 1998 Elsevier Science Ltd. All rights reserved.},
	keywords = {Concurrency control, Data structures, Database systems, Temporal databases},
	doi = {10.1016/S0306-4379(98)00015-5},
	url = {https://doi.org/10.1016/S0306-4379(98)00015-5},
	author = {Costas Vassilakis and N. Lorentzos and P. Georgiadis}
}
@conference {754888,
	title = {Implementing Embedded Valid Time Query Languages},
	booktitle = {DEXA {\textquoteright}98: Proceedings of the 9th International Conference on Database and Expert Systems Applications},
	year = {1998},
	month = {8},
	pages = {561{\textendash}572},
	publisher = {Springer-Verlag},
	organization = {Springer-Verlag},
	address = {London, UK},
	abstract = {Application development on top of database systems is heavily based on the existence of embedded and 4GL languages. However, the issue of designing and implementing embedded or 4GL temporal languages has not been addressed insofar. In this paper, we present a design approach for implementing an embedded temporal language that supports valid time. Furthermore, we introduce implementation techniques that can be used for implementing any embedded temporal language that supports valid time on top of a DBMS.},
	isbn = {3-540-64950-6},
	doi = {10.1007/BFb0054514},
	author = {Costas Vassilakis and P. Georgiadis and Sellis, Timos K.}
}
