14435501
Efa: an efficient content routing algorithm in large peer-to-peer overlay networks
An important issue for peer-to-peer application is to locate content within the network. There are many existing solutions to this problem, however, each of them addresses different aspects and each has its deficiencies. We focus on the unstructured peer-to-peer scenario and present a constrained flooding routing algorithm, Efa, which overcomes some of the deficiencies of those existing strategies. Efa performs application level broadcasting in a potentially very large peer-to-peer network overlaid on the Internet. Efa is completely decentralized and self-organized. It is a more scalable alternative to flooding, which is commonly used in unstructured peer-to-peer systems. Utilizing just a small amount of topology info, Efa is almost as simple as flooding, but it is much more efficient and scalable.
14840245
Grid Resource Discovery Using Semantic Communities
Grid technologies enable the sharing and collaborating of a wide variety of resources. To fully utilize these resources, effective resource discovery mechanisms are necessities. However, the complicated and dynamic characteristics of the grid resources make sharing and discovering them a challenging issue. In this paper, we propose a semantic community approach to assisting the efficient resource discovery and query in grids. Semantic community is a natural arrangement of distributed systems. It prunes the searching space and reduces the cost of searching. Moreover, it exhibits many desirable properties, including being fully decentralized and supporting complex queries. Our simulation results show how searching the girds can take advantage of semantic communities to reduce the searching cost and improve the quality of search results.
60653417
FedGrid: An HLA Approach to Federating Grids
Research on Grids has received considerable attention in recent years. Whereas existing work on connecting the grids primarily focused on grid services, in our work we propose a unified approach, so-called FederationGrid (or FedGrid for short), which integrates both virtual organization (VO) and grid services, thus enabling formation of virtual communities on top of grids. FedGrid is based on the standard High Level Architecture (HLA) that enjoys the advantages of high-level information modeling, including re-usability of software components and real-time performance of the overall systems. In addition, FedGrid is a fractal grid, comprised of hierarchical HLA federations, e.g. Realms and Lobby, which supports well the concept of virtual communities and scalability.
1602538
A scalable semantic routing architecture for grid resource discovery
Grids technology enables the sharing and collaborating of wide variety of resources. To fully utilize these resources, effective discovery techniques are necessities. However, the complicated and heterogeneous characteristics of the grid resource make sharing and discovering a challenging issue. In this paper, we propose a comprehensive semantic-based resource discovery framework, which performs an effective searching according to the semantic properties of what is searched. In the framework, nodes are grouped into clusters according to some criteria. Resources are indexed and aggregated with a highly compressed format. The summarized index can act as network knowledge to guide routing in the network. Intra-cluster and inter-cluster routing strategies are proposed to support scalable and efficient searching. Results from simulation demonstrate that this architecture is very effective in grid resource discovery.
40619710
An efficient clustered architecture for P2P networks
Peer-to-peer (P2P) computing offers many attractive features, such as self-organization, load-balancing, availability, fault tolerance, and anonymity. However, it also faces some serious challenges. In this paper, we propose an Efficient Clustered Super-Peer P2P architecture (ECSP) to overcome the scalability and efficiency problems of existing unstructured P2P system. With ECSP, peers are grouped into clusters according to their topological proximity, and super-peers are selected from regular peers to act as cluster leaders and service providers. These super-peers are also connected to each other, forming a backbone overlay network operating as a distinct, yet integrated, application. To maintain the dynamically adaptive overlay network and to manage the routing on it, we propose an application level broadcasting protocol: Efa. Applying only a small amount of information about the topology of a network, Efa is as simple as flooding, a conventional method used in unstructured P2P systems. By eliminating many duplicated messages, Efa is much more efficient and scalable than flooding, and furthermore, it is completely decentralized and self-organized. Our experimental results prove that ESCP architecture, combined with the super-peer backbone protocol, can generate impressive levels of performance and scalability.
16509401
Ontology-Based Clustering and Routing in Peer-to-Peer Networks
How to improve the performance of content searching in peer-to-peer (P2P) systems is a challenging issue. In this paper we attack this problem by proposing a new decentralized P2P architecture – ontology-based community overlays. The system exploits the semantic property of the content in the network to cluster nodes sharing similar interest together to improve the query and searching performance. Specifically, a distributed hash table (DHT) based overlay is constructed to assist peers organizing into communities. Those peers in the same community form a Gnutella-like unstructured overlay. This architecture helps reduce the search time and decrease the network traffic by minimizing the number of messages propagated in the system. Moreover, it retains the desirable properties of existing unstructured architectures, including being fully decentralized with loose structure, and supporting complex queries. We demonstrate by simulation, that with this architecture, peers can get more relevant resources faster and with less traffic generated.
10139207
Stochastic modeling of volume images with a 3-D hidden Markov model
Over the years, researchers in the image analysis community have successfully used various statistical modeling methods to segment, classify and annotate digital images. In this paper, we propose a 3-D hidden Markov model (HMM) for volume image modeling. A computationally efficient algorithm is developed to estimate the model. The 3-D HMM is applied to volume image segmentation and tested using synthetic images with ground truth. Experiments have demonstrated that 3-D HMM outperforms Gaussian mixture model based clustering by an order of magnitude in accuracy.
2572958
RACCOON: a peer-based system for data integration and sharing
Recent database applications see the emerging need to support data integration in distributed, peer-to-peer environments, in which autonomous peers (sources) connected by a network are willing to exchange data and services with each other. To address related research challenges, we are developing a system called "RACCOON", which allows different sources to integrate and share their data. We use an application to show several important features of the RACCOON system. The system also suggests semantic mappings for the user to choose. We show the two different querying modes, particularly how a query is expanded using the semantic mappings in the extended querying mode to compute as many answers to the query as possible.
15329835
Quality Evaluation in Flexible Machining Systems: A Flexible Fixture Case Study
Most of the studies in flexible manufacturing systems address the issues of flexibility, productivity, cost, etc. The impact of flexible lines on product quality is less studied. This paper presents a quantitative model based on Markov chain analysis to evaluate quality performance of a flexible machining system. A case study of flexible fixture is provided to illustrate the applicability of the method.
198665
Enhanced smart-card based license management
In many e-commerce (electronic commerce) situations, the owner of a digital object wants to enforce policies on the object after the object is in the customer's hands. The object can be thought of as being software, because data is often protected by forcing access to it to take place through a particular authorized software (e.g., a "reader" for an encrypted media file, in which case a license to view the movie is, in some sense, a "software license"). One of the ways that were proposed for such policy enforcement is the use of smart cards. We describe an enhanced solution to software license management based on tamper-resistant smart cards. Our public-key protocols for binding software licenses to smart cards improve on previous schemes in that they support flexible and partial transfers of licenses between cards. The license is verified by checking the presence of the associated card. The user can therefore have several software licenses all of which are bound to one card, to avoid juggling several cards in and out of the card reader.
14717043
BGP routing dynamics revisited
Understanding BGP routing dynamics is critical to the solid growth and maintenance of the Internet routing infrastructure. However, while the most extensive study on BGP dynamics is nearly a decade old, many factors that could affect BGP dynamics have changed considerably. We revisit this important topic in this paper, focusing on not only comparing with the previous results, but also issues not well explored before. We have found that, compared to almost a decade ago, although certain characteristics remain unchanged (such as some temporal properties), BGP dynamics are now â busier,â and more importantly, now have much less pathological behavior and are â healthierâ ; for example, forwarding dynamics are now not only dominant, but also more consistent across different days. Contributions to BGP dynamics by different BGP peersâ which are not proportional to the size of a peerâ s ASâ are also more stable, and dynamics due to policy changes or duplicate announcements are usually from specific peers