Department of Electronic & Computer Engineering 
Intelligent Systems Laboratory                           Pdi2etP TECHNICAL UNIVERSITY OF CRETE

 

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- General
- Architecture                 - Routing                         - Security                       - Alert Features              - Super-peer Environment - Client-peer Environment
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Architecture

There are two kinds of nodes in P2P-DIET: super-peer nodes and client nodes. All super-peers are equal and have the same responsibilities, thus the super-peer subnetwork is a pure peer-to-peer network (in terms of graph theory, it can be an arbitrary undirected graph). Each super-peer serves a fraction of the clients and keeps indices on the resources of those clients. A client node can run on the computer of a user. Resources (e.g., files in a file-sharing application) will be kept at client nodes, although it is possible in special cases to store resources at super-peer nodes. Clients are equal to each other only in terms of download. When a client wants to actually download a resource, it downloads it directly from the resource owner client. A client node can be connected to the network through a single super-peer node, which is the access point of the client. It is not necessary for a client to be connected to the same access point continuously i.e., client migration is allowed. Clients can connect, disconnect or even leave from the system silently at any time. To enhance the general form of the network, we also allow clients to use dynamic IP addresses.

 

Clients may publish a resource by sending a notification to their access point. Among other things, a notification contains metadata for the resource expressed in some metadata model e.g., AWPS, RDF etc. In the current implementation of P2P-DIET resource metadata are conjunctions of attribute-value pairs in the model AWPS. Since the current implementation targets resource sharing applications, attributes have been chosen to be the properties of the Dublin Core metadata element set. In the file-sharing application which currently runs on top of P2P-DIET, a resource can be a file of any type, for example, a music file or a Microsoft Word document.

P2P-DIET supports the typical ad-hoc query scenario of super-peer networks [Yang and Garcia-Molina, 2003]. A client can send a query to its access point and the access point will broadcast this query to all super-peers. In this way, answers will be produced for all matching network resources. Answers are returned to the access point of the client originating the query and are then passed to the client for further processing.

P2P-DIET also supports SDI scenarios. Clients may subscribe to the system with a profile (or long-standing query) expressing their information needs. Whenever a notification is generated at any point in the network, P2P-DIET makes sure that clients with profiles matching this notification are notified. A high-level view of the P2P-DIET architecture is shown in the above figure.

References:

  1. Yang and Garcia-Molina, 2003 B. Yang and H. Garcia-Molina. Designing a super-peer network. Proceedings of the 19th International Conference on Data Engineering (ICDE 2003), Bangalore, India, March 5--8, 2003.

 

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2003 Intelligent Systems Laboratory, TUC