SEKE 2012 Proceedings - Knowledge Systems Institute

y applying hash functions to its subject, predicate, and object.
Thus, all nodes know which nodes are responsible for the
triples they are looking for if the triples exist in the network. So,
we can implement approach M2 and M3 based on RDFPeers to
process SPARQL query as follows:
1) Approach M2: given a web ontology, it just publishes
the triples specified explicitly in it. Given a SPARQL query Q,
it retrieves the connected sub-graph of each entity appearing in
Q’s graph pattern to create an ontology to process Q.
2) Approach M3: given a web ontology, it publishes all
the triples, which are specified or implied in th e ontology.
Given a SPARQL query, according to entities appearing in the
query’s graph pattern, this approach retrieves all the relevant
triples to process the query.
Like our approach (M1) in this paper, given a SPARQL
query, if an ontology published can be reasoned out solutions,
approach M2 and M3 are sure to achieve the solutions. Here
we do not discuss it in detail.
B. Results and Analysis
Experiment 1 is conducted to evaluate our approach’s
consumption of network resources when ontology is published.
When we publish a web ontology by using approach M1, M2,
and M3 respectively, we count the total numbers of the values
to be inserted into P2P network according to each approach. In
fact, using the three approaches, when a value is inserted into
P2P network, the network must be accessed one time. Thus, the
total numbers of the values to be published is the number of
accesses to P2P network when ontology is published. The
experimental results are recorded in column M1, M2, and M3
in the Table I respectively.
TABLE I.
WEB ONTOLOGIES AND ITS NUMBERS OF THE VALUES PUBLISHED BY APPROACH M1, M2, AND M3
IRI of Ontologies from TONES M1 M2 M3 mulM2 mulM3
O1. file:/Users/seanb/Desktop/Cercedilla2005/hands-on/people.owl 291 950 5046 3.26 17.34
O2. http://keg.cs.tsinghua.edu.cn/ontology/software 174 867 4569 4.98 26.26
O3. http://www.mindswap.org/ontologies/family.owl 30 108 525 3.6 17.5
O4. http://www.co-ode.org/ontologies/pizza/pizza.owl 341 3345 30867 9.81 90.52
O5. http://www.owl-ontologies.com/Movie.owl 135 565 1605 4.19 11.89
O6. http://www.bpiresearch.com/BPMO/2004/03/03/cdl/Countries 67 498 1920 7.43 28.66
O7. http://www.semanticweb.org/ontologies/2007/9/AirSystem.owl 856 3398 65607 3.97 76.64
O8. http://protege.stanford.edu/plugins/owl/owl-library/koala.owl 65 247 1209 3.8 18.6
O9. http://www.loa-cnr.it/ontologies/DUL.owl 763 2689 38202 3.52 50.07
O10. http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl 196 439 1560 2.24 7.959
O11. http://www.mindswap.org/ontologies/debugging/university.owl 81 271 2823 3.35 34.85
O12. http://www.co-ode.org/ amino-acid/2006/05/18/amino-acid.owl 143 2291 4503 16 31.49
O13. http://www.mindswap.org/dav/commonsense/food/foodswap.owl 40 210 864 5.25 21.6
O14. http://www.estrellaproject.org/lkif-core/role.owl 271 1078 4083 3.98 15.07
O15. http://www.estrellaproject.org/lkif-core/lkif-top.owl 23 25 150 1.09 6.522
O16. http://www.semanticweb.org/ontolgies/chemical 127 398 14313 3.13 112.7
The total quantity of published data 3603 17379 177846 4.82 49.36
TABLE II.
NUMBERS OF ACCESSES TO P2P NETWORK FOR EACH QUERY PROCESS USING APPROACH M1, M2, AND M3
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q11 Q12 Q13 Q14 Q15 Total
M1 5 6 6 5 5 5 5 6 5 5 4 5 5 5 4 76
M2 1383 1383 22 56 129 171 124 231 231 171 1383 98 98 129 129 5738
M3 5 6 6 5 5 5 5 6 5 5 4 5 5 5 4 76
mulM2 276.6 230.5 3.67 11.2 25.8 34.2 24.8 38.5 46.2 34.2 345.8 19.6 19.6 25.8 32.25 75.5
mulM3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
TABLE III.
NUMBERS OF VALUES RETRIEVED FROM P2P NETWORK FOR EACH QUERY PROCESS USING APPROACH M1, M2, AND M3
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q11 Q12 Q13 Q14 Q15 Total
M1 5 6 6 5 5 8 5 6 5 6 4 5 5 5 4 80
M3 8547 8547 104 208 499 1025 564 946 946 1025 8547 429 429 499 499 32814
M2 2009 1726 403 2614 1708 1639 1692 1774 504 1735 1789 229 1821 2022 1926 23591
mulM2 1709.4 1424.5 17.33 41.6 99.8 128.13 112.8 157.67 189.2 170.83 2136.8 85.8 85.8 99.8 124.75 410.18
mulM3 401.8 287.67 67.17 522.8 341.6 204.88 338.4 295.67 100.8 289.17 447.25 45.8 364.2 404.4 481.5 294.89
In Table I, the column mulM2 (or mulM3) is the multiples
from column M2 (or M3) to M1. Table I shows that, for
approach M2, the multiples range from 1.09 to 16 and have a
weighted average value 4.82; for approach M3, the multiples
range from 6.522 to 112.7 and have a weighted average value
49.36. These imply that M1 can save large numbers of
accesses to network, because it just publishes a very smaller
quantity of values for a same ontology than M2 or M3. The
reason is that, M1 publishes an ontology just based on entities
and their roles appearing in the ontology, while M2 publishes
each triple specified three times and M3 publishes all the
specified and implied triples three times. An ontology usually
contains large numbers of triples, especially, the triples implied.
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