Routing Indices For Peer-to-Peer Systems Arturo Crespo, Hector Garcia-Molina Stanford ICDCS 2002.

Routing Indices For Peer-to-Peer Systems

Arturo Crespo, Hector Garcia-Molina

StanfordICDCS 2002

Motivation and ideas

Search (text) documents with specific keyword (category) in P2P network content-based

Users only interested in TOP 20 results

Each peer stores statistics of Documents shared by itself Documents shared by its neighbors

Route query to a “good” peer

Sequential search vs parallel search

Proposed Methods

Compound RI - naive

Hop-count RI - improved

Exponential RI - best

What is routing indices?

For A, there are 100 documents available from B (and its descendents)

20 belong to Database category 10 belong to Theory category 30 belong to Languages category

“Goodness” of a neighbor

i

isCRI

Documents OfNumber

)(Documents OfNumber

Computing goodness

For documents of “databases” and “languages”

75200

150

200

100200)(

0100

50

1000

01000)(

6100

30

100

20100)(

DGoodness

CGoodness

BGoodness

Updating of routing indices

New connection

RI propagation D+A+J

D+A+I

Proposed Methods

Compound RI – naive

Hop-count RI – improved

Exponential RI - best

Problems and improvements

Improved cost model take into account of query messages generated

Less update cost RI propagates through limited hops (horizon)

Robust against cycles

300 items

250 items

Hop-count RI

For W, it can reach 30 documents from Y 1 hop away

Y has 30 documents 50 documents from Y 2 hops away

Y1,Y2 have 50 documents

Goodness measure in Hop-count RI

Goodness of

hj ji

h F

QjNgoodnessQNiGoodness

..0

)],[(),(

33.53

102

33.103

310

33.163

1013

Z

Y

X

Proposed Methods

Compound RI – naive

Hop-count RI – improved

Exponential RI - best

Improvements

Hop-count RI exhibits High storage cost High update cost of RI

Compress RI of different Hops together

Similar to Compound RI with RI update method differs

RI Update

I changed to 70, 30, 10, 20, 50

RI Update

D update I’s row as 70, 30, 10, 20, 50

70 30 10 20 50

RI Update

D sent J’s update as 590, 86.67, 130, 70, 121.67

70 30 10 20 50

RI Update

70 30 10 20 50

590 86.67 130 70 121.67

D send A and update as 140, 75, 3.3, 75, 100

Experiment

Query Message generated

Why CRI, HRI, ERI perform much better in the uniform distribution?

Effect of index compression

Effect of cycles

Query message in different network topology

Update cost in different network topology

END