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Distributed Computing Systems, 2004. FTDCS 2004. Proceedings. 10th IEEE International Workshop on Future Trends of

Date 26-28 May 2004

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Displaying Results 1 - 25 of 62
  • Analysis and experimentation of an open distributed platform for synthetic traffic generation

    Page(s): 277 - 283
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (350 KB) |  | HTML iconHTML  

    This work presents an open distributed platform for traffic generation that we called distributed Internet traffic generator (D-ITG), capable of producing traffic (network transport and application layer) and of accurately replicating appropriate stochastic processes for both IDT (inter departure time) and PS (packet size) random variables. We implemented two different versions of our distributed generator. In the first one, a log server is in charge of recording the information transmitted by senders and receivers and these communications are based either on TCP or UDP. In the other one, senders and receivers make use of the MPI library. A complete performance analysis among centralized version and the two versions of D-ITG is presented. To our knowledge, no similar works are available. View full abstract»

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  • The vMatrix: server switching

    Page(s): 110 - 118
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1076 KB) |  | HTML iconHTML  

    Today most Internet services are pre-assigned to servers statically, hence preventing us from doing real-time sharing of a pool of servers across as group of services with dynamic load. Fluidly copying services in and out of servers remains a challenge due to the many dependencies that such services have on software, hardware, and most importantly, people. In this paper we present a novel solution, which builds on top of the classic operating systems concept of a virtual machine monitor (VMM). A VMM allows us to encapsulate the state of the machine in a virtual machine file, which could then be activated on any real machine running the VHM software. This eliminates the software dependencies problem by allowing us to move the whole machine around including the operating system, libraries, and third party modules that the service depends on. It eliminates the hardware dependencies problem by allowing us to mimic the hardware that the service expects regardless of the real hardware of the hosting machine. It also solves the people dependency problem by presenting the developers and system administrators with the same isolation model that they are used too with statically allocated servers. We describe our vMatrix framework in detail and address how to load balance the virtual machine services across the real-machines to maximize utilization efficiency (in terms of machines and people costs) such that total cost of the system is reduced without degrading the service performance and without requiring cost prohibitive code and architectural changes to existing legacy services. Our solution also offers additional side benefits like on-demand replication for absorbing flash crowds (in case of a newsworthy event like a major catastrophe) and faster failure recovery times. View full abstract»

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  • Platform-independent dynamic reconfiguration of distributed applications

    Page(s): 286 - 291
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (270 KB)  

    The aim of dynamic reconfiguration is to allow a system to evolve incrementally from one configuration to another at run-time, without restarting it or taking it offline. In recent years, support for transparent dynamic reconfiguration has been added to middleware platforms, shifting the complexity required to enable dynamic reconfiguration to the supporting infrastructure. These approaches to dynamic reconfiguration are mostly platform-specific and depend on particular implementation approaches suitable for particular platforms. In this paper, we propose an approach to dynamic reconfiguration of distributed applications that is suitable for application implemented on top of different platforms. This approach supports a platform-independent view of an application that profits from reconfiguration transparency. In this view, requirements on the ability to reconfigure components are expressed in an abstract manner. These requirements are then satisfied by platform-specific realizations. View full abstract»

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  • Two stage optimization of job scheduling and assignment in heterogeneous compute farms

    Page(s): 119 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (203 KB) |  | HTML iconHTML  

    Distributed networked computing in a compute farm environment has attracted great attention in recent years. Specialized management system for a compute farm enables heterogeneous distributed resources to be shared in a seamless way between various competing jobs. A key functionality of such system is a scheduler that controls the assignment of jobs to resources. This paper outlines a range of scheduling constrains as well as a list of required scheduling features for a state-of-the-art management system in distributed farm computing. It also presents a novel two stage static-dynamic scheduling algorithm to deal with the scheduling complexity. View full abstract»

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  • Introducing compositionality in Web service descriptions

    Page(s): 14 - 20
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (343 KB) |  | HTML iconHTML  

    Web services are essentially black box components from a composer's or a mediator's perspective. The behavioural description of any service can be asserted by the composer only through interface predicates exposed by the service provider Normally for proving properties of service compositions, pre/post conditions are found to be sufficient. However these properties are assertions only on the initial and final states of the service respectively. They do not help in specifying/verifying ongoing behaviour of an individual service or a composed system. We propose a framework for enriching service descriptions with two compositional assertions: assumption and commitment that facilitate reasoning about service composition and verification of their integration. The technique is based on interval temporal logic (ITL), a sound formalism for specifying and proving temporal properties of systems. View full abstract»

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  • Container based framework for self-healing software system

    Page(s): 306 - 310
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (239 KB) |  | HTML iconHTML  

    Software "self-healing" is an approach to detect improper operations of software applications, transactions and business processes, and then to initiate corrective action without disrupting users. The software engineering literature contains many studies on software error detection and error correction. In this paper, we introduce a "container based self-healing" framework and provide an outline on how the framework can help in evolving a self-healing system for a complex distributed system. View full abstract»

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  • A complexity measure for ontology based on UML

    Page(s): 222 - 228
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (294 KB) |  | HTML iconHTML  

    UML is a good tool to represent ontologies. When using UML for ontology development, one of the principal goals is to assure the quality of ontologies. UML class diagrams provide a static modeling capability that is well suited for representing ontologies, so the structural complexity of a UML class diagram is one of the most important measures to evaluate the quality of the ontologies. This paper uses weighted class dependence graphs to represent given class diagrams, and then presents a structure complexity measure for the UML class diagrams based on entropy distance. It considers complexity of both classes and relationships between the classes, and presents rules for transforming complexity value of classes and different kinds of relations into weighted class dependence graphs. This method can measure the structure complexity of class diagrams objectively. View full abstract»

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  • Grid computing in Taiwan

    Page(s): 201 - 204
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2496 KB) |  | HTML iconHTML  

    Grid computing focuses on aggregating resources (e.g., processor cycles, disk storage and contents) from a large-scale computing environment. It intends to deliver high-performance distributed platforms for computationand/or data-intensive applications. In this paper, we study the enabling techniques for Grid computing for high-performance computing. Our goals are to: (1) understand the design of these key components; (2) set up a Grid computing platform; (3) learn how to create Grid-enabled high-performance applications; and (4) share experiences on constructing such platforms and applications from the status of Taiwan. View full abstract»

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  • The power of DHT as a logical space

    Page(s): 325 - 331
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (273 KB) |  | HTML iconHTML  

    P2P DHT has fast become a rather "classical" research field. The currently popular mindsets are mostly routing-centric, or storage-centric. In this paper, we argue that it maybe more interesting to simply view DHT as a logical space that can dynamically size itself with potentially unlimited amount resources. This is in someway analogous to the virtual memory in any contemporary operating system. We believe that exploring such a perspective will bring about new insights as well as applications. We illustrate the power of this abstraction with a few examples, including self-scaling, self-healing fat tree, self-tune storage system, and a lightweight quorum-based distributed lock protocol which does not assume a constant number of members to start with. While their individual utilizations differ radically, all of them are united under this viewpoint. View full abstract»

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  • Self-aware distributed embedded systems

    Page(s): 102 - 107
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (354 KB) |  | HTML iconHTML  

    Distributed embedded sensor networks are now being successfully deployed in environmental monitoring of natural phenomena as well as for applications in commerce and physical security. Distributed architectures have been developed for cooperative detection, scalable data transport, and other capabilities and services. However, the complexity of environmental phenomena has introduced a new set of challenges related to sensing uncertainty associated with the unpredictable presence of obstacles to sensing that appear in the environment. These obstacles may dramatically reduce the effectiveness of distributed monitoring. Thus, a new distributed, embedded, computing attribute, self-awareness, must be developed and provided to distributed sensor systems. Self-awareness must provide the ability for a deployed system to autonomously detect and reduce its own sensing uncertainty. The physical constraints encountered by sensing require physical reconfiguration for detection and reduction of sensing uncertainty. Networked Infomechanical Systems (NIMS) consisting of distributed, embedded computing systems provide autonomous physical configuration through controlled mobility. The requirements that lead to NIMS, the implementation of NIMS technology, and its first applications are discussed here. View full abstract»

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  • A dynamic trust model for mobile ad hoc networks

    Page(s): 80 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB) |  | HTML iconHTML  

    This paper introduces a trust model for mobile ad hoc networks. Initially each node is assigned a trust level. Then we use several approaches to dynamically update trust levels by using reports from threat detection tools, such as intrusion detection systems (IDS), located on all nodes in the network. The nodes neighboring to a node exhibiting suspicious behavior initiate trust reports. These trust reports are propagated through the network using one of our proposed methods. A source node can use the trust levels it establishes for other nodes to evaluate the security of routes to destination nodes. Using these trust levels as a guide, the source node can then select a route that meets the security requirements of the message to be transmitted. This paper demonstrates important concepts for establishing a collaborative, dynamic trust model and for using this model as an example to enhance the security of message routing in mobile ad hoc networks. View full abstract»

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  • State management in Web services

    Page(s): 21 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (281 KB) |  | HTML iconHTML  

    In the paper, we identify a problem for certain applications wishing to use the Web service paradigm to enhance interoperability: rapid, robust state maintenance. While many features are available to support session data, special mechanisms for application state maintenance are less well developed. We discuss three different models to solve the problem and compare the advantages and disadvantages of each. Experimental results show that which model to use depends on application requirements. D-Stampede.NET is a platform supporting the development of applications that involve large time-sequenced data communication among heterogeneous clients. We describe our Web service implementation along with our state server solution to the application state management problem. A simple demonstration application is described and measured to validate performance. View full abstract»

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  • Mapping Web services specifications to process ontology: opportunities and limitations

    Page(s): 229 - 235
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1039 KB)  

    There are many XML based workflow and process modeling languages like XPDL, BPEL4WS etc. that can be used to define workflow and business processes in the Web services world. However, the use of XML makes the meaning of the processes ambiguous with limited capability to describe the relationships (semantics, schemas or ontologies) with respect to objects. Put into action, it becomes obvious that the integration of Web services will be hardly achieved without certain schema matching mechanisms supported by higher level abstraction. In this paper, the authors have developed a tool to support the mapping of business processes defined in BPEL4WS onto DAML-S based process ontology. This will overcome the weaknesses of the evolving BPEL4WS language; provide a powerful way to describe the objects and their relationships; and reduce the overhead of combinations required when mapping a BPEL4WS specification to other process definition languages. View full abstract»

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  • An architectural view of the entities required for execution of task in pervasive space

    Page(s): 37 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (299 KB)  

    Aiming to provide computation ubiquitously, pervasive computing is perceived as a means to provide a user with the transparency of anywhere, any place, anytime computing. Pervasive computing is characterized by execution of task in heterogeneous environments that use invisible and ubiquitously distributed computational devices. It relies on service composition that creates customized services from existing services by process of dynamic discovery, integration and execution of those services. In such an environment, seamlessly providing resource for the execution of the tasks with limited networked capabilities is further complicated by continuously changing context due to mobility of the user. To the best of our knowledge no prior work to provide such a pervasive space has been reported in the literature. In this paper we propose an architectural perspective for pervasive computing by defining entities required for execution of tasks in pervasive space. In particular we address the following issues, namely entities required for execution of the task, architecture for providing seamless access to resources in the face of changing context in wireless and wireline infrastructure, and dynamic aggregation of resources under heterogeneous environment. We also evaluate the architectural requirements of a pervasive space through a case study. View full abstract»

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  • Enterprise computing in the on demand era

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (194 KB) |  | HTML iconHTML  

    Web-based distributed computing is the vital technology enabler for today's most important e-business opportunities. However, a complex enterprise e-business system poses several technology challenges. Some of the key components that would enable the growth of an e-business are service-oriented architectures, understanding the use of data across businesses, application integration, and reduction of the complexity of management, and human intervention. In this position paper we outline some of the major challenges and trends in enterprise systems. View full abstract»

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  • Scalability in a Grid server discovery mechanism

    Page(s): 46 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (253 KB) |  | HTML iconHTML  

    Several kind of service discovery mechanisms already exist to look servers up in distributed systems. Each of them has its own properties and addresses specific service lookup issues. To provide access to computational servers, gathering a list of the available servers which can solve a given problem is not enough. Indeed, the characteristics of the servers have to be taken into account to optimize the global resource use. Thus, on a problem submission, a discovery service must collect from each server a prediction of the time needed to solve this problem according to its current load. An original server discovery mechanism has been developed to meet this specificity. This paper presents scalability issues when extending this service to a wide network and proposes some solutions. View full abstract»

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  • Estimating device availability in pervasive peer-to-peer environment

    Page(s): 254 - 260
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB) |  | HTML iconHTML  

    In pervasive computing environments, devices often communicate in a peer-to-peer manner, either for passing messages or collaboratively running applications. For any particular device, information about the availability of other devices can lead to more efficient communication and better execution of distributed tasks. For example, a device can distribute computation tasks to reliable devices and temporarily avoid unreliable ones. Since there usually is not a central server to coordinate or monitor the communication in such environment, a key technical challenge is for each individual device to predict the availability of other devices. In this paper, we describe some methods for predicting the availability of other devices using historic availability data of those devices obtained in routine usage. In this scheme, each device separately maintains data about the past communication with the other devices, and predicts current and future availability using the statistics of those data. These methods do not require any centralized monitoring or extra probing, and thus have very low computation cost. These characteristics make them suitable for small devices in a peer-to-peer environment. View full abstract»

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  • Towards an integrated architecture for peer-to-peer and ad hoc overlay network applications

    Page(s): 312 - 318
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (282 KB) |  | HTML iconHTML  

    Peer-to-peer (P2P) networks and mobile ad hoc networks (MANET) share some key characteristics: self-organization and decentralization, and both need to solve the same fundamental problem: connectivity. We motivate a study for the convergence of the two overlay network technologies and sketch an evolving architecture towards integrating the two technologies in building overlay network applications. View full abstract»

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  • Smart Phone: an embedded system for universal interactions

    Page(s): 88 - 94
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB) |  | HTML iconHTML  

    In this paper we present a system architecture that allows users to interact with embedded systems located in their proximity using Smart Phones. We have identified four models of interaction between a Smart Phone and the surrounding environment: universal remote control, dual connectivity, gateway connectivity, and peer-to-peer. Although each of these models has different characteristics, our architecture provides a unique framework for all of the models. Central to our architecture are the hybrid communication capabilities incorporated in the Smart Phones. These phones have the unique feature of incorporating short-range wireless connectivity (e.g., Bluetooth) and Internet connectivity (e.g., GPRS) in the same personal mobile device. This feature together with significant processing power and memory can turn a Smart Phone into the only mobile device that people will carry wherever they go. View full abstract»

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  • Pervasive communication: a human-centered service architecture

    Page(s): 140 - 146
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (726 KB) |  | HTML iconHTML  

    In the last few years, a variety of concepts for user-centered systems have gained momentum. The vision of I-centric communications and the according reference model are good examples for this development. This reference model represents a first approach of human-centered telecommunication systems, which is based on service adaptation, service integration, and IP-based reachability. The integrated adaptability feature enables the pervasive availability of services. Ambient-awareness and personalization complete this fundamental characteristic of I-centric services. This paper elaborates the main features of the reference model for I-centric communications including business models, ambient awareness, and personalization to show the their relevance for the realization of pervasive communication systems. View full abstract»

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  • Friendly object tracking and foreign object detection and localization with an SDAC wireless sensor network

    Page(s): 30 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB) |  | HTML iconHTML  

    This paper presents a proof-of-concept wireless sensor network for detecting and tracking friendly objects and detecting and localizing foreign objects. The network incorporates a novel sensor network methodology to sense its surroundings, decide in-network what the situation in its surroundings is, act on this decision, and communicate its results to a user (SDAC). The system also performs in-network data fusion and data reduction and demonstrates the use of an adaptable hardware and software platform. The end user is presented with a geographical information systems (GIS) viewer showing when and where objects are detected. The viewer is able to display tracking information about friendly objects by searching a database for events involving specific friendly objects. View full abstract»

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  • A distributed buffer management approach supporting IPv6 mobility

    Page(s): 270 - 276
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (466 KB)  

    In wireless local area networks (WLAN), mobility support is essential for providing seamless services. The current Mobile IP standard suffers several problems, especially for accommodating real-time media applications. Most of the existing studies focus on improving the performance between the home agent (HA) and foreign agent (FA). In this work, we propose a buffer management approach to enhance the performance between the mobility agent (HA or FA) and the mobile node (MN). The proposed scheme deals with the packet delivery between MA and MN in Layer 2. Through the simulation, we show that our scheme improves TCP throughput as well as reducing the UDP packet loss rate. Moreover, its implementation is feasible in both IPv4 and IPv6, and suitable for supporting quality of service (QoS). View full abstract»

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  • Providing network monitoring service for Grid computing

    Page(s): 52 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (273 KB) |  | HTML iconHTML  

    Collecting, correlating and extracting network performance information is an important premise for effective Grid applications and services. Based on the intrinsic relationship between the Internet and Grid computing, we extend the network performance monitoring activities in the Internet to the Grid scenario and develop a scalable, interoperable Grid network measurements and monitoring system (GMMPro) which is mainly derived from the principle of the simple network management protocol (SNMP). The advantages of SNMP-based monitoring are manifold: (1) the interface between this monitoring architecture and its client (other Grid services or applications) is simple and has been widely accepted in the Internet environment; (2) multiple measurements and monitoring engines (MME) are introduced to provide system scalability and flexibility; (3) the configurable feature of GMMPro could provide special configurable service for particular application needs and the preferred passive measurement methodologies enhance system scalability in large-scale deployment. Some preliminary measurement results in practice are also presented in the paper. View full abstract»

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  • CA-PLAN, an inter-organizational workflow model

    Page(s): 154 - 162
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    Workflow management systems (WfMS) are accepted worldwide due to their ability in modeling and controlling business processes. In the past, we defined an intra-organizational workflow specification model, Process Language Plan. Plan, with the associated tools, allows user to describe the graph specification for processes, artifacts and participants' organization. PLAN has been successfully implemented in Agentflow and run with workflow (Agentflow) applications. Plan and most current WfMS adopt the centralized architecture in an organization, so that they can be applied in an organization only. The participants in different organizations cannot serve one another with workflows. In this paper, we present an interorganizational workflow model, Collaborative Agentflow Process Language. CA-PLAN, extended from PLAN, lets workflow systems inside an organization be specified as workflow services provided by the organization. Its interorganizational architecture lets a user specify work applications as in Plan. Besides, the related service techniques and supporting tools provided in Agentflow systems are presented. View full abstract»

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  • Grid computing in Hong Kong: research and development

    Page(s): 205 - 208
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB) |  | HTML iconHTML  

    Grid is a new exciting arena for re-application of many distributed computing techniques from the past as well as brand new ideas because of new requirements imposed upon by a form of computing that was never possible before. We present the Hong Kong Grid which is a major Grid platform for local institutions to conduct their R and D projects. View full abstract»

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