1. ICDCS 2008 @ Beijing China Routing of XML and XPath Queries in Data Dissemination Networks Guoli Li, Shuang Hou Hans-Arno Jacobsen Middleware Systems Research Group University of Toronto

2. ICDCS 2008 @ Beijing China Agenda Motivation Advertisement-based routing Covering Evaluation Conclusions

3. ICDCS 2008 @ Beijing China Motivation Data sources: publish XML data Data users: register XPath queries The data dissemination network: deliver matching results to a large and dynamically changing group of users Content-based Data Dissemination … XML … Queries Results

4. ICDCS 2008 @ Beijing China Publish/Subscribe Publisher Subscriber Subscription (XPath) Publication (XML) Advertisement (DTD) Subscriber Matching of XMLs and XPaths [ICDE’06] Matching of Advertisements and XPaths Exploring relations among XPaths

5. ICDCS 2008 @ Beijing China Covering-based Routing 34 5 6 1 2

6. ICDCS 2008 @ Beijing China Language Model Advertisement: generated from DTDs Non-recursive advertisement  e.g., A = /t1/t2/t3…/tn-1/tn Recursive advertisement  Simple A = A1(A2)+A3  SeriesA = A1(A2)+A3(A4)+A5  EmbeddedA = A1(A2(A3 )+ A4)+A5 … /personnel/person /personnel/person/name /personnel/person/name/family /personnel/person/name/given /personnel/person/email /personnel/person/url /personnel/person/link DTD Advertisements

7. ICDCS 2008 @ Beijing China Language Model Subscription: XPaths Absolute e.g., /c/d/*/e Relative e.g., c/d/*/e Descendant operators e.g., c//e/*/c c d e * e * c b a

8. ICDCS 2008 @ Beijing China Advertisement-based Routing P(A) P(S) P(A) P(S) P(A) P(S) Subscription (S) Broker A1: /a/b/*/e A2: /b/e A3: /a/b/d A4: /a/b/e …

9. ICDCS 2008 @ Beijing China Overlapping Algorithms 00012 S = /a /b /c /* /b /e AdvSubOverlap **Y *tY t*Y ttY t1t2N Next Table A = /a /b /c /* /b /c /* /b /e /a /b /c /* /b /c /* /b /e /a /b /c /* /b /e /a /b /c /* /b /c /* /b /e /a /b /c /* /b /e /a /b /c /* /b /c /* /b /e e.g, S = /a /b //c /* /b //e Basic case: Other cases:

10. ICDCS 2008 @ Beijing China Subscription Tree Subscriptions are maintained in a hierarchical tree A child has more than one parent Siblings may intersect If a publication does not match a node, it does not match any of the descendants ROOT /a /b/e/c/f /*/bd/a/b /a/b/a/c/a/*/d /a/b/d/a/c/d /b/d/b/e /b/d/a pointer

11. ICDCS 2008 @ Beijing China Tree Maintenance Insert Delete

12. ICDCS 2008 @ Beijing China Covering Algorithms Similar to Adv-Sub overlapping algorithms Absolute simple XPEs Relative simple XPEs XPEs with // operator e.g., S1S2Cover **Y *tY t*N ttY t1t2N S2 = /a /a /* //c /e /c /d S1 = /* /a //e /c /a /a /*//c /e /c /d /* /a /e /c /a //c /e /c /d/*

13. ICDCS 2008 @ Beijing China Merging Rules Rules XPEs with one difference (e.g., element, op) e.g., S1= /a/*/c/d S2 = /a/*/c/e S = /a/*/c/* XPEs with different sub-XPEs e.g., … XPE1 XPE2 … S1 S2 … S // Merge degree P(S1) P(S2) P(S)

14. ICDCS 2008 @ Beijing China Evaluation Setup Implemented in C++ Overlay with 127 content-based routers Cluster (each node:1.86GHz, 4G) vs. PlanetLab Workloads are generated from two DTDs: NITF and PSD Metrics Number of subscriptions per router Network traffic XPE processing time Notification delay

15. ICDCS 2008 @ Beijing China Routing Table Size

16. ICDCS 2008 @ Beijing China Routing Table Size

17. ICDCS 2008 @ Beijing China Network Traffic MethodNetwork TrafficDelay(ms) No-Adv-No-Cov654,87197.82 No-Adv-With-Cov572,89020.74 With-Adv-No-Cov398,81098.09 With-Adv-With-Cov326,79620.89 With-Adv-With-CovPM254,90016.78 With-Adv-With-CovIPM257,56712.24

18. ICDCS 2008 @ Beijing China Process Time

19. ICDCS 2008 @ Beijing China Notification Delay (PSD)

20. ICDCS 2008 @ Beijing China Notification Delay (NITF)

21. ICDCS 2008 @ Beijing China Related Work Locating data sources in large distributed systems [Galanis et al. 2003] DHT based approach Data summary Query aggregation for scalable data dissemination [Chan et al. 2002] Equivalence between the original query set and the aggregated set ONYX [Diao et al. 2004] Deliver part of the XML documents Share common prefixes among queries using NFA XTreeNet [Fenner et al. 2005] Unify the pub/sub model and the query/response model Avoid repeatedly matching at each hop

22. ICDCS 2008 @ Beijing China Conclusions Investigate advertisement-based routing for XML data dissemination networks Propose a novel data structure to maintain covering & merging relationships among XPEs. Perform experimental evaluation on a 127 broker overlay to demonstrate the approach Reduce routing table by up to 90% Improve routing latency by roughly 85% Future work Extend to tree patterns Share common prefixes among XPEs in overlapping and covering algorithms

23. ICDCS 2008 @ Beijing China Q & A Contact gli@cs.toronto.edu jacobsen@eecg.toronto.edu Middleware systems research group, University of Toronto www.msrg.eecg.toronto.edu

24. ICDCS 2008 @ Beijing China Process Time Number of Subscriptions 500100015002000250030003500400045005000 Time (ms) 0 20 40 60 80 100 120 140

25. ICDCS 2008 @ Beijing China Notification Delay (NITF)

26. ICDCS 2008 @ Beijing China Notification Delay (PSD) Number of Hops 23456 0 4 8 12 16 Notification Delay (ms)

27. ICDCS 2008 @ Beijing China False Positives

28. ICDCS 2008 @ Beijing China Conclusions Investigate advertisement-based routing for XML data dissemination networks Present algorithms to determine the covering relations among arbitrary XPEs Propose a novel data structure to maintain covering & merging relationships among XPEs. Explore rules to merge similar XPEs in order to further reduce the routing table size Perform experimental evaluation on a 127 broker overlay to demonstrate the approach Reduce routing table by up to 90% Improve routing latency by roughly 85%