P2P流媒体传输外文翻译文献.docx

1、P2P 流媒体传输外文翻译文献P2P流媒体传输外文翻译文献(文档含中英文对照即英文原文和中文翻译)原文：Peer-to-Peer Streaming Media DeliveryPeer-to-Peer ArchitectureWhatever definitions have been put upon it, peer-to-peer is an effective rallying cry for a new way of doing things. Many do not consider it a new way; it has been argued that the curren

2、t interest in peer-to-peer is merely the pendulum swing between centralized and decentralized systems.That cycle can be described as :1. Decentralize to remove bottlenecks2. Centralize to increase efficiencyNonetheless, the particular inflection point of resources available on the Internet at this t

3、ime has allowed peer-to-peer systems to exhibit remarkablescalabilityandresourceexchange.Thispaperbriefly describes a different way of looking at the resources available in these systems; it then illustrates the applicability of peer-to-peer systems to content delivery.Peer-to-peer is used broadly t

4、o describe a variety of network systems that generally run at the presentation, session, and application layers, although ad-hoc networks and other systems use the same concepts from the physical layer up. Specifically, peer-to-peer spans content delivery, collaboration,caching,businessprocessautoma

5、tion,supplychain management,gridcomputing,distributedcomputation, business-to-businessexchanges,datadeployment,usertouser communication, user communities, ad-hoc networks, and the Internet itself. Perhaps peer-to-peer should be considered more of an architectural approach than a specific technology

6、or business approach.An way of seeing if a problem is susceptible to a peer-to-peer approach is to ask, “If every client in this system could also provide the service they consume, would there be a benefit?”It is not always the case that there is a benefit; many database applicationsrequirecentraliz

7、ationforsecurityandsimplicityofadministration, for example.Unusual Peer-to-Peer ExamplesThe oft-cited ICQ and Napster are two pioneering peer-to-peer examples. Both provide an alternative system to DNS for naming, (an attribute of some peer-to-peer definitions ) and both provide the ability for user

8、s to directly communicate, providing the “person-to-person” aspect also associated with peer-to-peer.There are, however, a variety of other systems providing earlier examples of the shift towards peer-to-peer systems. If peer-to-peer is considered as a quality with a gradient scale, ranging from cli

9、ent-server to a more equilateral power of computing systems, any system that provides a higher ratio of servers to clients could be regarded as peer-to-peer.Quake was (and remains) a 3d online multiplayer video game. Quake (and later QuakeWorld) provided a client-server system for synchronized video

10、 gaming. The servers were usually high bandwidth, high powered systems, but due to the demands of online video gaming, so were the clients. And in Quake, the server was actually embedded in the client application, blurring the distinction between clients and servers and allowing any node to act (by

11、user selection) as a client or a server.Among millions of online Quake players, there eventually existed tens of thousands of servers on the Internet, and so the ratio of clients to servers began to even out.ShoutCast was designed as a plug-in to a popular MP3 player that enabled live streaming of M

12、P3 audio over an HTTP connection. Users could use ShoutCast to create a radio station (on the Internet) based on their MP3 collection. This allowed serving from a client application, and increased the ease for an end user in configuring this server.Peer-to-peer Resourcesn Storagen CPUn BandwidthStor

13、age and CPU cycles tend to be the two resources most commonly cited in peer-to-peer systems. There are, however, several resources that, isolated, can be used to better describe the range of optimizations available through peer-to-peer approaches.Bandwidth is a resource that is transient and non-rec

14、apturable. In the same way that unused airline seats cannot be recaptured as a resource, bandwidth, when available and unused, is lost to time. The first stage of consumer Internet expansion involved a great disparity between client bandwidth and server bandwidth,but asbroadband equalizes this resou

15、rce, it becomes available to a peer-to-peer system.n Presencen Latency/ProximityPresence can be viewed as a resource. When the p in p2p stands for“person” (as in instant messaging scenarios), presence is the resource of that person being online and available for communication at that time. This enab

16、lesonline collaborationbecause it provides at a glance notification of availability.Latency and proximity are two relatively unremarked resources that are key to interactive simulations on the Internet. Quake provides an example of a large number of servers (Quake servers) located with an alternative namespace system