1 / 22

An Optimal Broadcast Algorithm for Content- Addressable Networks

An Optimal Broadcast Algorithm for Content- Addressable Networks. Ludovic Henrio Fabrice Huet Justine Rochas. Background Efficient Algorithm Experiments. General Motivation – RDF Storage. Context Web Semantic : RDF data C hallenge Store and retrieve RDF data

mizell
Télécharger la présentation

An Optimal Broadcast Algorithm for Content- Addressable Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 18/12/2013 - OPODIS (Nice) An Optimal BroadcastAlgorithmfor Content-Addressable Networks Ludovic Henrio Fabrice Huet Justine Rochas

  2. BackgroundEfficient AlgorithmExperiments

  3. General Motivation – RDF Storage • Context • Web Semantic: RDF data • Challenge • Store and retrieve RDF data • Large scalesetting • Our solution • Content Addressable Network

  4. Content-Addressable Networks (CAN) 1 E B C • Overlay network • Nodes are peers A • Structuredorganization • MultidimensionalCartesianspace • Entirelypartitioned D dim #2 • A zone ismanaged by one peer • A zone = a (hyper)rectangle 0 1 dim #1 • Neighborhoodbased on adjacent zones • Routing = successivelyapproaching value in all dimensions

  5. Problem: Cost of Queries 2 queries over 2 variables: conjunction of two 2-dimensional broadcast NOT OK • Naivebroadcastdoes not scale OK OK 1 query over 2 variables 1 query over 1 variable

  6. Problem: Duplicated Messages 1 • Duplicated messages • 11 peers 40 messages ! • How to eliminateduplicates? • For eachpeerP • Find the peerthatisreponsiblefor sending the message to P E dim #2 0 1 dim #1

  7. Existing Solutions • Use the CAN structure to route messages • Meghdoot [1] « upperLeft » predicate • M-CAN [2] • M-CAN principles • Initiatorpeersends to all neighbors • Otherpeersforward to neighbors on • Same dimension on opposite side • Lower dimensions on all sides • Forwarding on the last dimension depends on a constraint Meghdoot: startfrom a corner A C B [1] A. Gupta, O. D. Sahin, D. Agrawal, A. El Abbadi: Meghdoot: Content-Based Publish/Subscribe over P2P Networks. Middleware 2004

  8. M-CAN Execution Message Message that leads to duplication INIT Corner Constraint [2] S. Ratnasamy, M. Handley, R. M. Karp, S. Shenker: Application-Level Multicast Using Content-Addressable Networks. Networked Group Communication 2001

  9. PreliminaryWork • Existence of an optimal algorithmproved [3] • A solution to exhibit existence • Valid for a verygenericdefinition of CAN • Not efficient (execution time) • Parallelize messagessendingonlywhenreaching a « border » INIT [3] Francesco Bongiovanni, Ludovic Henrio: A Mechanized Model for CAN Protocols. FASE 2013

  10. BackgroundEfficient AlgorithmExperiments

  11. Hypothesis and Goals • CAN = adjacent rectangles • No additional structure • ToleratechurnsbetweentwoBcast • Not implementation-dependent • Do not toleratechurnsduringBcast • Optimal in number of messages and good parallelization INIT A spanningtree

  12. Efficient Algorithm – Principle • Removes all duplicates • In all dimensions • How ? • Uses the corner constraint • Plus a spatial constraint • A set of fixed values • Reducethe problem • Appliesrecursively spatial constraint in 2D CAN spatial constraint in 3D CAN

  13. Efficient Algorithm • Observation #1 • Easyto forward in 1D • Observation #2 • Only one zone touches a corner • Idea of the algorithm • Suppose an efficient broadcast in dimension N • Apply on a hyperplane of dimension N - 1 • Send to bothsidesof thishyperplaneusing the corner constraint • Repeatuntil the hyperplaneisjust a line (dimension 1)

  14. Efficient Algorithm – Execution Message Message that leads to duplication INIT Corner Constraint Spatial Constraint

  15. Efficient Algorithm – Properties • Proved to becorrect • All peersreceive a broadcast message at least once • Proved to beminimal • All peersreceive a broadcast message atmostonce • Elements of proof – Whenreceiving on dimension D: • dim < D spatial constraintissatisfied • For dim = D ascending or descending direction • dim > D corner constraintissatisfied • This algorithmisoptimal • All peersreceive a broadcast message exactly once

  16. BackgroundEfficient AlgorithmExperiments

  17. Experimental Setup • Using the Grid5000 platform • Multisiteexperimentation • Deployment • From 50 to 1500 peers • Up to 200 physical machines • CAN setting • Successivelysplit zones in half • Zone to split ischosenrandomly C A B

  18. Number of messages Maximum gain of 5.3 MB

  19. Number of messages

  20. Execution Time Significantspeedup

  21. Conclusion: Broadcast on CAN • Wefound an optimal solution • Proved to becorrectand optimal • Efficient on large scale settings • Support range multicast • Currentlyin use in the EventCloudproject [4] • Management of RDF data • Algorithmused for one year • Tested and approved ! A range multicast EventCloud [4] http://www.play-project.eu/solutions/event-cloud

  22. dim #1 dim #3 dim #2

More Related