Manolis Marazakis

Publications of Manolis Marazakis

• Information Cities Over The Internet;

  Authors: Jakka Sairamesh, Petros Kavassalis, Manolis Marazakis, Christos Nikolaou

  09/2002;

  In the coming years, we expect many kinds of medium and large-scale information sites to emerge over the Internet, which will represent or mimic small and large "physical" cities. They will provideIn the coming years, we expect many kinds of medium and large-scale information sites to emerge over the Internet, which will represent or mimic small and large "physical" cities. They will provide local and global information and services to registered inhabitants. Just like physical cities, these "information cities" (iCities) will house "infohabitants" who will participate in activities such as navigating the city, performing commercial transactions, socializing, and collaborating. We are already witnessing the emergence of large-scale web portals providing local information about cities, access to local government services, community services and a place for businesses to advertise and attract consumers on-line. In this paper, we present a taxonomy of information cities

• Aurora: An Architecture for Dynamic and Adaptive Work Sessions in Open Environments

  Authors: Manolis Marazakis, Dimitris Papadakis, Christos Nikolaou

  12/1999;

  . This paper presents the Aurora architecture for networkcentric applications, complementing the CORBA and WWW=Java frameworks with support for composition of services. The architecture addresses the. This paper presents the Aurora architecture for networkcentric applications, complementing the CORBA and WWW=Java frameworks with support for composition of services. The architecture addresses the requirements of dynamic open environments with multiple autonomous service providers. The paper presents a detailed technical design of the run-time infrastructure that enables on-demand composition of services. Aurora is based on a container framework, which provides the basis for dynamic and adaptive composition, as well as detailed monitoring and tracking. Work sessions are implemented as networks of active containers. A distinguishing feauture of Aurora is that such networks can be inspected and manipulated at run-time. 1 Introduction In open and dynamic environments, such as the Internet, a network-centric application paradigm is becoming popular, as a means to utilize widely distributed application components and information resources that are made available by autonomous...

• Market-driven Service Allocation in a QoS-capable Environment

  Authors: Spyros Lalis, Christos Nikolaou, Dimitris Papadakis, Manolis Marazakis

  12/1999;

  In this paper we describe a prototype that supports end to end QoS for applications invoking services over an ATM switch. The required resources are allocated to applications via auctions takingIn this paper we describe a prototype that supports end to end QoS for applications invoking services over an ATM switch. The required resources are allocated to applications via auctions taking place in two independent markets. We investigate the effects of market independence in the behavior of the system, and report results of experiments with alternative system configurations and workloads. Finally, we demonstrate the adaptability of the system in a dynamic open environment. Keywords: electronic trading, QoS, resource management, multiple resources 1. Introduction With the rapid increase of electronically available services and the growth of open computing environments such as the Internet, we are about to witness the birth of true electronic economies. In tomorrow's applications, the user will merely specify the task to be performed as well as the desired performance characteristics, while the system will dynamically select the underlying services to implement this task. S...

• Management of Work Sessions in Dynamic Open Environments

  Authors: Manolis Marazakis, Dimitris Papadakis, Christos Nikolaou

  12/1999;

  Workflow management systems are developed to support and automate the execution of business processes, by assigning tasks to agents according to the workflow specification. Current state-of-the-artWorkflow management systems are developed to support and automate the execution of business processes, by assigning tasks to agents according to the workflow specification. Current state-of-the-art workflow systems are mainly concerned with the routing and assignment of tasks, providing little support for tasks related to administration and management. This deficiency is exacerbated in dynamic open environments, where services provided and managed by multiple autonomous authorities need to be integrated. Such environments significantly stretch the assumptions underlying current state-of-the-art workflow system designs, especially as network-centric applications become widespread. In this paper we propose a framework, service level management, for addressing all system administration in an integrated manner, in the context of a workflow execution model that allows for dynamic adaptation (reconfiguration) of work sessions in a dynamic and heterogeneous run-time environment. Service level...

• Effects of an Asynchronous Resource Allocation Protocol on End-to-End Service Provision

  Authors: Spyros Lalis, Manolis Marazakis, Dimitris Papadakis

  12/1999;

  In this paper we present results of experiments that were performed to quantify the effects of retries in an asynchronous resource allocation protocol that is employed for end-to-end serviceIn this paper we present results of experiments that were performed to quantify the effects of retries in an asynchronous resource allocation protocol that is employed for end-to-end service provision. A major finding from our experiments is that an application class may be penalized by experiencing delays in accessing a shared resource as a result of overload on resources used by other application classes, which are unknown to this class. In turn, these delays may cause under-utilization of other resources used by this application class. Moreover, we illustrate how such effects emerge simply by varying the relative occurrence frequencies of application classes, but without changing the overall request arrival process. It is shown that such changes can lead to undesirable performance effects for all classes that share a number of resources. Keywords: multi-resource allocation, electronic trading, autonomous open systems, workload dynamics, end-to-end service provision 1. Int...

• The Impact of Workload Clustering on Transaction Routing

  Authors: Christos Nikolaou, Alexandros Labrinidis, Volker Bohn, Donald Ferguson, Michalis Artavanis, Christos Kloukinas, Manolis Marazakis

  01/1999;

  The qualitative and quantitative description of the workload of a system is very important for capacity planning and performance management. In large-scale transaction processing systems, dynamicThe qualitative and quantitative description of the workload of a system is very important for capacity planning and performance management. In large-scale transaction processing systems, dynamic workload control algorithms are applied to optimize system performance. Such algorithms can benefit from the results of workload clustering algorithms that partition the workload into classes consisting of units of work exhibiting similar characteristics. This paper presents CLUE, a clustering environment for OLTP workload characterization. CLUE provides a library of clustering algorithms that classify transactions into classes, according to their database reference patterns. This paper introduces HALC, a new batch-mode heuristic clustering algorithm, designed to cope with the large volume of input data that is typical for real-life applications. Next, an on the fly clustering algorithm based on neural networks is described. This algorithm can be used in an on-line fashion in systems whose ch...

• Synthesis of Services in Open Commerce Environments

  Authors: Christos Nikolaou, Manolis Marazakis, Dimitris Papadakis

  03/1998;

  This paper addresses the issue of integrating several technologies for realising electronic commerce solutions that go beyond the current state-of-the-art. Integration enables synthesis of servicesThis paper addresses the issue of integrating several technologies for realising electronic commerce solutions that go beyond the current state-of-the-art. Integration enables synthesis of services offered by multiple diverse autonomous service providers. This is achieved in the framework provided by the Aurora architecture for network-centric applications. This architecture complements the CORBA and WWW=Java frameworks with support for coordination and collaboration and addresses the requirements of dynamic open environments with multiple autonomous service providers. Keywords: electronic commerce, open environments, network-centric applications, coordination, collaboration, open market paradigm 1 Introduction Electronic commerce is a distributed process that involves complex interactions among multiple trading parties. In an open market, there are many providers of goods and services, and there may be intermediaries providing more complex services by combining offerings from multipl...

• The Aurora Architecture for Developing Network-Centric Applications by Dynamic Composition of Services

  Authors: Manolis Marazakis, Dimitris Papadakis, Christos Nikolaou

  02/1998;

  This paper presents the Aurora architecture for network-centric applications. This architecture complements the CORBA and WWW=Java frameworks with support for coordination and collaboration andThis paper presents the Aurora architecture for network-centric applications. This architecture complements the CORBA and WWW=Java frameworks with support for coordination and collaboration and addresses the requirements of dynamic open environments with multiple autonomous service providers. The paper presents a detailed technical design of the run-time infrastructure that enables on-demand composition of services. A specification language, called HERMES, provides constructs for describing events, tasks, and work sessions. Aurora is based on a container framework, which provides the basis for dynamic and adaptive composition, as well as detailed monotoring and tracking. A repository service, together with a metadata framework, enable interoperability for integration of services. Keywords: workflow management, coordination, collaboration, network-centric applications, open environments Contents 1 Introduction 5 1.1 Motivation : : : : : : : : : : : : : : : : : : : : : : : : : : : ...

• Efforts Towards on Open Electronic Commerce Infrastructure for the Tourism Industry.

  Authors: Penelope Constanta, Manolis Marazakis, Dimitris Papadakis, Christos Nikolaou, Dietmar Boenke

  01/1998

• Transaction Routing for Distributed OLTP Systems: Survey and Recent Results.

  Authors: Christos Nikolaou, Manolis Marazakis, G. Georgiannakis

  Inf. Sci. 01/1997; 97:45-82.

• Towards a Common Infrastructure for Large-scale Distributed Applications.

  Authors: Christos Nikolaou, Manolis Marazakis, Dimitris Papadakis, Yiorgos Yeorgiannakis, Jakka Sairamesh

  Research and Advanced Technology for Digital Libraries. First European Conference, ECDL '97, Pisa, Italy, 1-3 September, Proceedings; 01/1997

• Towards Adaptive Scheduling Of Tasks In Transactional Workflows

  Authors: Manolis Marazakis, Christos Nikolaou

  09/1995;

  This paper discusses dynamic workload management in transaction processing systems where the workload consists of multiple classes of units of work, including workflows comprised of interdependentThis paper discusses dynamic workload management in transaction processing systems where the workload consists of multiple classes of units of work, including workflows comprised of interdependent tasks. Business requirements specify that differing levels of service must be provided to different classes of work, thus it is natural to specify performance goals per work class, that reflect the business requirements for the work class as well as the inherent resource demands of the units of work. Adaptive algorithms have been proposed for the satisfaction of performance goals of transaction classes. Scheduling the execution of complete workflows, which are multitransaction units of work, is complicated by the need for task coordination, due to both control and data flow dependencies among tasks. Current transaction processing monitors provide infrastructure for the coordination of tasks by means of queueing facilities. We draw on previous work on goal-oriented resource management to desig...

• The HERMES Language for Work Session Specification

  Authors: Manolis Marazakis, Dimitris Papadakis, Christos Nikolaou

  02/1970;

  This paper presents the HERMES specification language, which is introduced to express scripts for complex activities involving coordination and collaboration. The language is part of a framework forThis paper presents the HERMES specification language, which is introduced to express scripts for complex activities involving coordination and collaboration. The language is part of a framework for network-centric applications, providing a two-level framework for expressing metadata. Service flow rules define communication channels between software components and actions triggered by run-time events. The semantics of HERMES supports a model for dynamic and adaptive work sessions in open environments. 1. Introduction In open and dynamic environments, such as the Internet, a network-centric application paradigm emerges, with emphasis on utilizing widely distributed distributed application components and information resources that are made available by autonomous providers. Applications are created by building new services (either client- or server-side) that integrate and customize existing services. Clients use Internet protocols to interact with the server-based parts of the applica...

• A Framework for the Encapsulation of Value-Added Services in Digital Objects

  Authors: Manolis Marazakis, Dimitris Papadakis, Stavros A. Papadakis

  02/1970;

  . Container technology enables the encapsulation of information content together with rules and controls specifying the types of content usage permitted and the consequences of usage, such as. Container technology enables the encapsulation of information content together with rules and controls specifying the types of content usage permitted and the consequences of usage, such as triggering of report generation and payment. Containers have been proposed as a mechanism for securing intellectual property rights. This paper outlines other possible applications of container technology, including support for compound documents that incorporate active content, and automation of processes involving multi-party peer-to-peer interactions for the purposes of collaboration and commerce. Such value-added services are of particular interest in the context of digital libraries aiming to provide functionality extending beyond that of a simple repository of electronic documents. This paper presents the design of a container framework in the context of an architecture for network-centric applications. 1 Introduction In the context of digital library systems and electronic doc...

• System-level Infrastructure Issues for Controlled Interactions among Autonomous Participants in Electronic Commerce Processes

  Authors: Manolis Marazakis, Dimitris Papadakis, Christos Nikolaou, Penelope Constanta

  02/1970;

  Electronic commerce in open large-scale distributed environments presents several system-level challenges in terms of execution model, infrastructure, and management. The autonomy of providersElectronic commerce in open large-scale distributed environments presents several system-level challenges in terms of execution model, infrastructure, and management. The autonomy of providers severely restricts the scope of control by authorities other than the owner of each service, and makes the design of the distributed software architecture a challenging undertaking. In this paper we present our ongoing work toward the development of a distributed software substrate to support controlled interactions among components that are owned and managed by autonomous authorities. This infrastructure is based on a distributed component model, designed to support the paradigm of servicelevel management for specifying and managing commitments made by independent service providers to their clients on performance-related attributes of services. 1. Introduction It is expected that electronic commerce applications will be required to support mixing and matching of products and services, on a per...

• System Infrastructure for Digital Libraries: A Survey and Outlook

  Authors: Christos Nikolaou, Manolis Marazakis

  02/1970;

  . This paper focuses on technical issues regarding the challenge of integrating digital libraries in a work support environment that combines information management with coordination and. This paper focuses on technical issues regarding the challenge of integrating digital libraries in a work support environment that combines information management with coordination and collaboration. Such broad scope necessitates an extended view of electronic documents to allow for combinations of information content together with executable components. Moreover, as a result of the autonomy of the service and information content providers, this environment takes the form of an information economy. This paper provides a brief survey of research results related to architectures, metadata, interoperability and rights management in digital library systems. This survey serves to support a discussion of extending the scope of digital library systems toward integrated work support environments. 1 Introduction Digital libraries extend and augment their physical counterparts by facilitating access to existing information resources and services, and by providing enhanced support...

• Towards a Common Infrastructure for Large-Scale Distributed Applications

  Authors: Christos Nikolaou, Manolis Marazakis, Dimitris Papadakis

  02/1970;

  This paper discusses the requirements of current and emerging large-scale distributed applications and emphasizes the need for a common infrastructure to support them. A design for an infrastructureThis paper discusses the requirements of current and emerging large-scale distributed applications and emphasizes the need for a common infrastructure to support them. A design for an infrastructure that aims at satisfying these requirements is presented. Moreover, it is shown how key aspects of important large-scale applications can exploit the services included in the proposed infrastructure. The paper concludes by discussing the current status of a prototype implementation and our research plan. 1 Introduction In this paper we consider a view of digital library systems that goes beyond that of a repository of on-line information, to provide support throughout all phases of work. As concluded in [22], users need to find, analyze, and understand information of widely diverse types. They need to re-organize the information to use it in multiple contexts, and to manipulate it in collaboration with others. For this view to become reality, it is important to acknowledge that performing ...

• Decentralized resource acquisition from autonomous markets in a QoS-capable environment

  Authors: Spyros Lalis, Dimitris Papadakis, Manolis Marazakis

  Decision Support Systems.

  We present a protocol for acquiring multiple resources that are traded through autonomous markets. Further, we describe the protocol's application to and implementation in a prototype system thatWe present a protocol for acquiring multiple resources that are traded through autonomous markets. Further, we describe the protocol's application to and implementation in a prototype system that supports prioritized end-to-end QoS for applications invoking services over an ATM switch. The corresponding network and server resources are allocated to applications via auctions that are performed independently of each other. Finally, we investigate the effects of market autonomy and protocol design in the performance of the system by discussing results of experiments for alternative system configurations and workloads.