Grid Computing, 7700 Guest ! Dr Ian Taylor [email protected] P2P and Grids. Grid computing Globus Service-based Grid computing Grids and P2P What is P2P Why P2P - history P2P definition Gnutella Scalability. Grid Computing: Globus Tools GT2. Recap: consists of four elements:
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Grid Computing, 7700
Dr Ian Taylor
Recap: consists of four elements:
And of course:
Foster I, Kesselman C and Tuecke S, (2001) The Anatomy of the Grid: Enabling Scalable Virtual Organizations
XML + Envelope
Are the converging?
IP addresses changing
The 1990's Client-Server Internet
Late 1990’s Naptser, then Gnutella 2000 – the new P2P
What is an P2P application?
P2P is a class of applications that takes advantage of resources e.g. storage, cycles, content, human presence, available at the edges of the Internet – Clay Shirky
2. User A searches for song.mp3
4. Server informs User A of the location of song.mp3
5. User A connects to User C and downloads song.mp3
3. Server searches database. Finds song on User C’s machine
The ‘Animal’ GNU: Either of two large African antelopes (Connochaetes gnou or
C. taurinus) having a drooping mane and beard, a long tufted tail,
and curved horns in both sexes. Also called wildebeest.
GNU: Recursive Acronym
GNU’s Not Unix ….
Nutella: a hazelnut chocolate spread produced by the Italian confectioner Ferrero….
History Of Gnutella
Gnutella, GNU GPL, 0.56 (Feb 2000)
And now I am trying to be cool … and writing songs …
We are Geeky and Rich !
What is Gnutella?
Gnutella is a protocol for distributed search
Searching a Gnutella Network: Broadcasting
3-D Cayley Tree
Searching in Gnutella involves broadcasting a Query message to all connected peers. Each connected peer will send it to their connected peers (say 3) and so on. Typically, this search will run 7 hops. If the number of connected peers, c=3 and the hops i.e. TTL=7 then the total number of peers searched (in a fully connected network) will be:
S = c + c2 +c3 + ….. ch = 3 + 9 + 27 + 81 + 243 + 729 + 2187 = 3279 Nodes
Searching a Gnutella Network: From one Node
Searching a Gnutella Network: All nodes
Proved that the social network of the United States is indeed connected with a path-length (number of hops) of around 6 – The 6 degrees of separation !
Does this mean that it takes 6 hops to traverse 200 million people??
Centralized + Decentralized
The figure below is a view of the topology of a Gnutella network as shown on the LimeWire web site, the popular Gnutella file-sharing client. Notice how the power-law or centralized-decentralized structure is demonstrated.