Dienstag, 21. Dezember 2010

CS6223 Distributed Systems 無善無惡是心之體 RPC Remote Procedure Call : 10 steps

CS6223 Distributed Systems RPC Remote Procedure Call : 10 steps

1. The client procedure calls the client stub in the normal way.
2. The client stub builds a message and calls the local operating system.
3. The client's OS sends the mesage to the remote OS.
4. The remote OS gives the message to the server stub.

5. The server stub unpacks the parameters and calls the server.
6. The server does the work and returns the result to the stub.
7. Theserver stub packs it in a message and calls its local OS.
8. The server' OS sends the message to the client's OS.

9. The client's OS gives the message to the client stub.
10.The stub unpacks theresult andreturns to the client.


Give-to-Get: Free-riding-resilient Video-on-Demand in P2P Systems

Centralised solutions for Video-on-Demand (VoD) services, which stream pre-recorded video content to multiple clientswho start watching at the moments of their own choosing, are not scalable because of the high bandwidth requirements of
the central video servers.

Peer-to-peer (P2P) techniqueswhich let the clients distribute the video content among themselves,can be used to alleviate this problem.

However, such techniques may introduce the problem of free-riding, with some peers
in the P2P network not forwarding the video content to others if there is no incentive to do so.

When the P2P network contains too many free-riders, an increasing number of the well-behaving peers may not achieve high enough download speeds to maintain an acceptable service.

In this paper we propose Give-to-Get, a P2P VoD algorithm which discourages
free-riding by letting peers favour uploading to other peers who have proven to be good uploaders.

As a consequence, free-riders are only tolerated as long as there is spare capacity in the system. Our simulations show that even if 20% of the peers are free-riders, Give-to-Get continues to provide good performance to the well-behaving peers.

In particular, they show that Give-to-Get performs very well for short videos, which dominate the current VoD traffic on the Internet.

Keywords: multicasting, video streaming, video-on-demand, peer-to-peer, free-riding."

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