Apostolos Gkamas

@article{3090,

title = {Broadband Municipal Optical Networks in Greece: A Suitable Business Model},

author = {Christos Bouras and Apostolos Gkamas and Thrasivoulos Tsiatsos and J Papagiannopoulos and George Theofilopoulos},

url = {https://telematics.upatras.gr/4870sdarticle1/},

year  = {2009},

date = {2009-01-01},

urldate = {2009-01-01},

journal = {Journal of Telematics and Informatics, Elsevier Science},

pages = {391 - 409},

abstract = {This paper proposes a business model for the optimal exploitation of the currently developing broadband metropolitan area networks in Greece. Having recorded and examined relevant international practices, we describe in detail the way that these networks should be managed, operated, maintained and expanded. Taking into consideration that these infrastructures will widely alter the broadband map of Greece, that Greece has currently one of the lowest broadband penetration percentages in Europe and that the proper exploitation strategy of the networks to be deployed could boost the demand for broadband connections and applications, the application of the optimal business model appears to be of vital importance. We describe the proposed business model in detail, including ways for expanding the broadband infrastructures, as well as tackling of viability issues regarding the authority responsible for managing the broadband metropolitan networks.},

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@article{3159,

title = {Adaptive transmission of multimedia data over the Internet [Article in Encyclopedia]},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},

url = {https://telematics.upatras.gr/358716/},

year  = {2008},

date = {2008-01-01},

urldate = {2008-01-01},

pages = {16 - 22},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{3167,

title = {Business Models For Municipal Broadband Networks},

author = {Christos Bouras and Apostolos Gkamas and Thrasivoulos Tsiatsos and George Theofilopoulos},

url = {https://telematics.upatras.gr/3094ist457/},

year  = {2008},

date = {2008-01-01},

urldate = {2008-01-01},

pages = {457 - 465},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{3165,

title = {Multicast of Multimedia Data},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},

url = {https://telematics.upatras.gr/8567316/},

year  = {2008},

date = {2008-01-01},

urldate = {2008-01-01},

pages = {316 - 322},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{3163,

title = {Quality of Service and Service Level Agreements},

author = {Christos Bouras and Apostolos Gkamas and Dimitris Primpas and Kostas Stamos},

url = {https://telematics.upatras.gr/1361418/},

year  = {2008},

date = {2008-01-01},

urldate = {2008-01-01},

pages = {418 - 424},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{3162,

title = {Quality of Service architectures [Article in Encyclopedia]},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},

url = {https://telematics.upatras.gr/3961425/},

year  = {2008},

date = {2008-01-01},

urldate = {2008-01-01},

pages = {425 - 431},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{3166,

title = {Real-time protocols - RTP/RTCP [Article in Encyclopedia]},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},

url = {https://telematics.upatras.gr/6733463/},

year  = {2008},

date = {2008-01-01},

urldate = {2008-01-01},

pages = {463 - 468},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{3161,

title = {The IPv6 protocol [Article in Encyclopedia]},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},

url = {https://telematics.upatras.gr/2351257/},

year  = {2008},

date = {2008-01-01},

urldate = {2008-01-01},

pages = {257 - 262},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{3024,

title = {IPv6 Deployment: Real Time Applications and QoS Aspects},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},

url = {https://telematics.upatras.gr/1003com_comipv62006_bouras/},

year  = {2006},

date = {2006-01-01},

urldate = {2006-01-01},

journal = {Computer Communications Journal, Elsevier Science},

number = {1393 - 1401 },

pages = {Vol. 29, No. 9, 1393 - 1401},

abstract = {This paper gives an overview of the issues related to the QoS mechanisms under IPv6 and the transition of applications to the new Internet protocol. We describe the implementation and testing of a QoS service on IPv6 networks, which is based on the DiffServ architecture (expedited forwarding) and provides strict priorities to packets that are produced from real time applications. The service was implemented and tested at the 6NET large-scale IPv6 network, and additional advanced testing was performed in a local testbed. We present and analyze the results from our tests under a number of different scenarios. In addition, we focus on issues regarding application transition to IPv6 and we briefly discuss as a case study the transition of OpenH323 protocol stack to support IPv6. We also discuss the usage and the expected impact of the new Flow Label field in the IPv6 header.},

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pubstate = {published},

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@article{3030,

title = {Application on Demand System over the Internet},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas and I Nave and A Shani and O Sheory and Y Tzruya},

url = {https://telematics.upatras.gr/71371131/},

year  = {2005},

date = {2005-08-01},

urldate = {2005-08-01},

journal = {Journal of Network and Computer Applications, Academic Press, Vol. 28, No. 3},

pages = {209 - 232},

abstract = {This paper describes the design and implementation of the ASP-NG system. The main modules of the ASP-NG system are the AoD service and the Web Portal. The ASP-NG Portal is a portal for providing the user with the necessary interface in order to access an Application on Demand (AoD) service. The ASP-NG portal is responsible for the interaction with the user of the AoD service. Using the AoD service the user rents an application for a limited time period at a fraction of the actual cost of the application. The AoD service is responsible for downloading the appropriate parts of the application according to the user’s actions, while enforcing the mutually agreed frame between the user and the Application Service Provider (ASP). The implementation of the ASP-NG portal is based on the Web Services of the Java 2, Enterprise Edition platform and the implementation of the AoD module is based onCCCprogramming language. The ASP-NG portal offers to its users the capability to select and customize the language of the user interface in order to present information in their preferred language. Moreover the ASP-NG portal offers to the portal administrator the capability to customise the look and feel of the ASP-NG portal.},

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pubstate = {published},

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@article{3028,

title = {SRAMT: A hybrid sender and receiver-based adaptation scheme for TCP friendly multicast transmission},

author = {Christos Bouras and Apostolos Gkamas},

url = {https://telematics.upatras.gr/39101106/},

year  = {2005},

date = {2005-03-01},

urldate = {2005-03-01},

journal = {Computer Networks Journal, Elsevier Science, Vol. 47, No. 4},

pages = {551 - 575},

abstract = {In this paper,we describe a hybrid sender and receiver-based adaptation scheme for multicast transmission of multimedia data,which we call SRAMT (Sender–Receiver based Adaptation scheme for Multicast Transmission). The most prominent features of SRAMT are its distributed (to sender and receivers) transmission rate estimation algorithm and its innovative RTT (Round Trip Time) estimation algorithm based on one-way delay measurements. With the use of SRAMT,we ensure that sender will transmit TCP friendly traffic and receivers with different capabilities (in terms of available bandwidth) are able to receive the multimedia information. We evaluate SRAMT through a number of simulations and compare it with other schemes available to the literature. Main target of the simulations was the examination of SRAMT behavior to a heterogeneous group of receivers and its behavior against TCP connections.},

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pubstate = {published},

tppubtype = {article}

}

@article{3027,

title = {Architecture and Performance Evaluation for Redundant Multicast Transmission Supporting Adaptive QoS},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and A Karaliotas},

url = {https://telematics.upatras.gr/27201103/},

year  = {2005},

date = {2005-01-01},

urldate = {2005-01-01},

journal = {Tools and Applications, Kluwer Academic Publishers, Vol. 25, No. 1},

pages = {85 - 110},

abstract = {In this paper we describe the architecture of an application that was developed for the transmission of multimedia data, using the multicast mechanism, over the Internet. There are two major issues that have to be considered when designing and implementing such a service, the fairness and the adaptation schemes. The fairness problem results from the fact that Clients with different capabilities have to be served. In our application we use a mechanism that categorizes the Clients into a number of groups according to each Client’s capabilities and (the mechanism) serves each group of Clients with a different multicast stream. With the term “capabilities” we do not only mean the processing power of the Client, but also the capacity and the condition of the network path towards that Client. Because of today’s Internet heterogeneity and the lack of Quality of Service (QoS) support, the Server cannot assume that the Clients will permanently be able to handle a specific bit rate.We have therefore implemented an additional mechanism for the intra-stream bit rate adaptation. The proposed mechanism uses a “friendly” to the network users congestion control policy to control the transmission of the data. We evaluate the adaptive multicast transmission mechanism through a number of experiments and a number of simulations in order to examine its behaviour to a heterogeneous group of Clients and its behaviour against TCP and UDP data streams.},

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pubstate = {published},

tppubtype = {article}

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@article{3031,

title = {Porting and performance aspects from IPv4 to IPv6: The case of OpenH323},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},

url = {https://telematics.upatras.gr/5031fulltext/},

year  = {2005},

date = {2005-01-01},

urldate = {2005-01-01},

journal = {International Journal of Communication Systems, Wiley InterScience, Vol. 18, Issue 9},

pages = {847 - 866},

abstract = {This paper is a summary of our experiences on a case study for porting applications to IPv6. We present the results of the effort to port OpenH323, an open-source H.323 platform to IPv6, which we believe can serve as guidelines for other projects with similar goals. We briefly present the structure of the OpenH323 platform. We also discuss a number of issues arising during the porting of a platform to IPv6, like which would be the easiest approach to the porting procedure, how compatibility with earlier, IPv4-only versions of the platform could be retained, if there are any useful tools for assisting this task, how and when one could be positive that the necessary modifications had been made, and which testing procedures should be followed. We then present a variety of experiments that we conducted in order to comparatively evaluate the IPv4 and IPv6 protocol stacks. We also present the results of some initial experiments comparing IPv4 and IPv6 performance under congested network links and the conclusions that they lead us to.},

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pubstate = {published},

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@article{3034,

title = {Performance Evaluation of the Impact of Quality of Service mechanisms in an IPv6 network for IPv6 - capable real time applications},

author = {Christos Bouras and Apostolos Gkamas and Kostas Stamos and Dimitris Primpas},

url = {https://telematics.upatras.gr/5894jnsm2006_ipv6/},

year  = {2004},

date = {2004-12-01},

urldate = {2004-12-01},

journal = {Journal of Network and Systems Management, Kluwer Academic Publishers, Volume 12, Issue 4},

pages = {463 - 483},

abstract = {This paper describes a Quality of Service (QoS) service on an IPv6 domain that aims to service aggregates of real-time traffic with minimum delay, jitter, and packet loss. It contains results from the tests that were performed in order to configure and evaluate the QoSmechanisms.As an actual example of real-time traffic, we have used heOpenH323 project, an open source H.323 implementation that has been ported to IPv6. The QoS mechanisms in IPv6 networks is still a field that has not been researched adequately, and we therefore present the results from the experiments in our IPv6 network that took advantage of the QoS mechanisms. This QoS service uses the Modular QoS CLI (MQC) mechanism and especially the Low Latency Queue feature (LLQ) in order to treat packets from real-time applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

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@article{3046,

title = {Multimedia Transmission with Adaptive QoS based on Real Time Protocols},

author = {Christos Bouras and Apostolos Gkamas},

url = {https://telematics.upatras.gr/2618818/},

year  = {2003},

date = {2003-01-01},

urldate = {2003-01-01},

journal = {International Journal of Communications Systems, Wiley InterScience, Volume 16, Issue 2},

pages = {225 - 248},

abstract = {In this paper, we describe a mechanism for adaptive transmission of multimedia data, which is based on real-time protocols. The proposed mechanism can be used for unicast or multicast transmission of multimedia data over heterogeneous networks, like the Internet, and has the capability to adapt the transmission of the multimedia data to network changes. In addition, the implemented mechanism uses an inter-receiver fairness function in order to treat the group of clients with fairness during the multicast transmission in a heterogeneous environment. The proposed mechanism uses a ‘friendly’ to the network users congestion control policy to control the transmission of the multimedia data. We implement a prototype application based on the proposed mechanism and we evaluate the proposed mechanism both in unicast and multicast transmission through a number of experiment and a number of simulations in order to examine its fairness to a group of clients and its behaviour against transport protocols (TCP) and UDP data streams.},

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tppubtype = {article}

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@article{3043,

title = {Evaluation of Teleteaching Services over ATM and IP Networks},

author = {Christos Bouras and Vaggelis Kapoulas and Apostolos Gkamas and Thrasivoulos Tsiatsos},

url = {https://telematics.upatras.gr/77901080/},

year  = {2003},

date = {2003-01-01},

urldate = {2003-01-01},

journal = {Journal of Telematics and Informatics, Elsevier Science, Vol. 20, Issue 1},

pages = {1 - 18},

abstract = {This paper presents the components of a synchronous teleteaching application, their underlying technology and their interaction with network services. In addition, it presents the architecture and design of a synchronous teleteaching application used over the public ATM network in Greece. This paper presents various teleteaching scenarios over an ATM network infrastructure with the use of native ATM and IP over ATM. In each scenario we present the standards used, the logical components, the resource demands (network and equipment) and its special characteristics. For each scenario we give detailed information about the transmission and frame rates and the video delay. The main result of our experiments is that broadband networks offer many capabilities for high quality teleteaching, and generally speaking, high quality telematic services.},

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pubstate = {published},

tppubtype = {article}

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@article{3055,

title = {An environment for the annotation of multimedia material by younger children},

author = {Christos Bouras and Apostolos Gkamas and Afroditi Sevasti},

url = {https://telematics.upatras.gr/3318782/},

year  = {2002},

date = {2002-01-01},

urldate = {2002-01-01},

journal = {Journal of Educational Multimedia and Hypermedia, (JEMH), AACE, Vol. 11, Issue 4},

pages = {363 - 385},

abstract = {The exceptional advent of interactive multimedia applications has led to the need for their exploitation for educational purposes. In this article, the design and implementation of a multimedia annotation environment for young children is presented. This environment was developed to provide children aged 4 - 8 with the opportunity to reflect upon and annotate episodes from their everyday life. The aim was to exploit the latest technological developments in the field of multimedia, to build an annotation environment where children would be able to add multimedia annotations to videos. Apart from the environment itself, design choices, interface realization, as well as media handling methods and performance issues are also presented.},

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pubstate = {published},

tppubtype = {article}

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@article{3060,

title = {Network-Based Distributed Learning Environment},

author = {Christos Bouras and Apostolos Gkamas and Thrasivoulos Tsiatsos},

url = {https://telematics.upatras.gr/8232625/},

year  = {2000},

date = {2000-07-01},

urldate = {2000-07-01},

journal = {WebNet Journal: Internet, Technologies, Applications & Issues, AACE, Vol.2},

pages = {29 - 37},

abstract = {Today we can register a growing public interest in the Internet and especially in the World Wide Web (WWW or Web). At the same time, the computer networks are becoming increasingly fast with the use of new technologies. Moreover new Internet protocols like the RTP/RTCP (Real-time Transport Protocol/Real-time Transport Control Protocol), which have characteristics such as payload type, time-stamping, and numbering of data packets, make possible the transmission, over the Internet, of real time multimedia information offering Quality of Services (QoS). These achievements make possible the implementation of tools that offer teleteaching capabilities over the Internet with QoS characteristics. All the above described achievements make the implementation of tools that offer synchronous learning, asynchronous learning and Computer Support Collaborative Work for Learning (CSCW/L) capabilities over the Internet possible.},

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pubstate = {published},

tppubtype = {article}

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@article{3061,

title = {Efficient Web-Based Open and Distance Learning Services},

author = {Christos Bouras and Apostolos Gkamas and Thrasivoulos Tsiatsos and P Destounis and J Garofalakis and G Sakalis and B Sakopoulos and J Tsaknakis},

url = {https://telematics.upatras.gr/3513564/},

year  = {2000},

date = {2000-01-01},

urldate = {2000-01-01},

journal = {Journal of Telematics and Informatics, Elsevier Science, Vol. 17, Issue 3},

pages = {213 - 237},

abstract = {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  cogently, as required in a web tele-training application, for each type of information maintained,  event strategies must be deployed according to their behavior and structure. The diversity and complexity of data, the network aspect of the application and web decencies impose an architecture design incorporating a plethora of technologies and tools that must be integrated in such a fashion that they  cogently organize 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 vendor independent 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) ores 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.

},

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