SocioPlug

Polystyrene: Survivable Shape for Self-Organising Data

François Taïani

Joint work with:

Hoel Kervadec (INSA Rennes)Simon Bouget (ENS Rennes)Anne Marie Kermarrec (ASAP)

F. Taiani 2

Focus Epidemic Topology Construction algorithms

Decentralized, fast, scalable Fundamental building block to higher-level services

(DHT, Multicast, Pub-Sub, Recommendations)

Taken from [JMB09]

Problem: Catastrophic Failure

The topology heals But the overall shape is lost

How to recreate whole shapefrom surviving nodes?

?

F. Taiani 4

Outline

Background:Decentralized Topology Construction

Polystyrene:Architecture and Protocol

Evaluation Outlook

Decentralized Topology Const. Each node : some data Find k “closest” nodes in system

Decentralized approach, asynchronous rounds

random sampling (RPS)

topology layer gossip-based topology construction (e.g. T-Man)

topology linkrandom link

AB

C

D

E

AB

C

D

E

node node position

Main idea: greedy neighbourhood optimization

Decentralized Topology Const.

exchange ofneighbors lists

neighborhoodoptimization

1 2

F C

E D

AB

C

D

F

E

AB

C

D

F

E

Polystyrene

Topology Construction(T-Man, Vicinity, Gossple)

Neighbours

Peer Sampling Service(RPS, Cyclon, SCAMP)

Node position

Polystyrene’s Architecture

Polystyrene Protocolrecovery

2

FD

Topology Construction

migration

4

projection3

Node position

ghosts

backup (outgoing)

1

backup (incoming)

1’

Neighbours3’

guests

F. Taiani 9

The Migration Process

q.post

p.post

p.guestst

q.guestst

a

b

c

df

e

p q

F. Taiani 10

The Migration Process

Bi-clustering of guest points Heuristics : diameter

a

b

c

df

e

p q

F. Taiani 11

The Migration Process

Bi-clustering of guest points Heuristics : diameter

a

b

c

df

e

points closer to b

points closer to d

p q

F. Taiani 12

The Migration Process

Bi-clustering of guest points Heuristics : diameter + minimum move

q.post+1

p.post+1

q.guestst+1

a

b

c

df

e p.guestst+1

points closer to b

points closer to d

p q

F. Taiani 13

Evaluation Shape : 2D 40x80 logical torus Round 20 : 50% correlated node crashes

Polystyrene recreates shapewith surviving nodes

After failure (r=20) (r=22) (r=28)

Eval: Quality of Neigborhoods

Polystyrene maintains good neighborhoods

Eval: Quality of Shape

And the torus gets restored!

F. Taiani 16

Eval: Scalability Time (rounds) until homeogeneity less than

Logarithmic convergence!

Outlook An example of advanced topology construction

Replicated, highly robust, self-organising

Potential extension to load-balancing Good for plug heterogeneity

Concrete application on top of polystyrene DHT, recommendation, queries, search

Larger picture Self-organising data primitives for plug infrastructures

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References [KMG03] Kermarrec A.-M., Massoulie L., Ganesh, A.J., Reliable Probabilistic

Communication in Large-Scale Information Dissemination Systems, IEEE Transactions on Parallel and Distributed Systems, March 2003, (14:3)

[JGK04] Jelasity, M., Guerraoui, R., Kermarrec, A.-M., and van Steen, M. (2004). The peer sampling service: experimental evaluation of unstructured gossip-based implementations. Middleware ’04, pages 79–98, New York, NY, USA. Springer- Verlag New York, Inc.

[VS05] Voulgaris, S. & Steen, M. V. Epidemic-style Management of Semantic Overlays for Content-Based Searching. Proc. of the 11th Int. Euro-Par Conf. on Parallel Processing (Euro-Par'05), Springer, 2005, 1143-1152

[Jelasity, Alberto Montresor, and Ozalp Babaoglu. 2009. T-Man: Gossip-based fast overlay topology construction. Comput. Netw. 53, 13 (August 2009), 2321-2339.

[BFG+10] Bertier, M.; Frey, D.; Guerraoui, R.; Kermarrec, A.-M. & Leroy, V.The GOSSPLE anonymous social network. Proc. of the ACM/IFIP/USENIX 11th Int. Conf. on Middleware, 2010, 191-211

[TLB14] Taiani, F., Lin, S. and Blair, G. S. (2014) GossipKit: A Unified Component Framework for Gossip. IEEE TSE, Preprint, doi: 10.1109/TSE.2013.50