Funcionamiento P2P

A Platform for Peer-to-Peer Communications and its Relation to Semantic Web Applications
Norihiro Ishikawa1, Takeshi Kato1, Hiromitsu Sumino1, Johan Hjelm2, Ye Yu3, and Zhongwu Zhu3
NTT DoCoMo Inc, 3-5 Hikarino-oka, Yokosuka, Kanagawa, Japan {t_kato, ishikawa, sumino}@mml.yrp.nttdocomo.co.jp http://www.nttdocomo.co.jp/English/ 2 Ericsson Research, Torshamnsgatan 23, Kista SE-16480, Stockholm,Sweden Johan.Hjelm@era.ericsson.se 3 Ericsson Research Japan, 3-5 Hikarino-oka, Yokosuka, Kanagawa, Japan {Ye.Yu, Zhong-Wu.Zhu}@nrj.ericsson.se
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Abstract. The peer-to-peer service has entered the public limelight over the last few years. Several research projects are underway on peer-to-peer technologies, but no definitive conclusion is currently available. Compared to traditional Internettechnologies, peer-to-peer has the potential to realize highly scalable, extensible, and efficient distributed applications. This is because of its basic functions: resource discovery, resource sharing, and load balancing in a highly distributed manner. An easy prediction is the emergence of an environment in which many sensors, people, and many different kinds of objects exist, move, and communicatewith one another; it is called the "ubiquitous communication environment". Peer-to-peer is one of the most important and suitable technologies for ubiquitous networking since it supports discovery mechanisms, simple one-to-one communication between devices, free and extensible distribution of resources and distributed search to handle the enormous quantities of resources. Peer-to-peercommunication raises issues such as efficient resource discovery mechanisms and interoperation. The Semantic Web technology is one key to assuring that peer-to-peer can resolve these issues. The Semantic Web technology adequately can describe resource information. RDF (Resource Information Framework) is attracting attention for its flexibility. One of the purposes of this study is to explore a ubiquitouspeer-to-peer network architecture that will allow various devices to communicate with one another across various networks. The other is to explore the applicability of the Semantic Web technology to peer-to-peer systems. We have been designing an architecture and protocols for realizing peer-to-peer networking among various devices. We are currently designing APIs for peer-to-peer applications andimplementing a prototype peerto-peer networking infrastructure toward the ubiquitous communication environment. We are also considering semantic peer-to-peer applications and developing prototypes over our ubiquitous peer-to-peer network.

1 Introduction
From its beginning the Internet has used conventional cooperative technologies such as the server-client approach to handle network resourcesand provide Internet services. This offers advantages in that Internet services can be regulated by just a few central servers, but some major concerns have been raised, such server overload and cost, and the demand for mutual and direct communications between many clients. As a result, the peer-to-peer technology has become popular and has been used in networks that handle vast amounts of datadaily. It can balance the loads over a large number of servers and so is being used for applications such as distributed search [1], file sharing [2] [3], distributed storage [4] and groupware [5]. Additionally, a generalized platform for peer-to-peer applications has been proposed [6] and developed. At the same time, various devices have recently been extended by the addition of communicationabilities. In the near future, an environment where many sensors, persons and different kinds of objects exist, move, and communicate with one another, called the "ubiquitous communication environment", will appear. In fact, peer-to-peer communication is one of the most important and suitable networking technologies for ubiquitous networking since it easily supports one-to-one communication between...