evaluation and comparison

In this page we provide further information about the evaluation of swget and its comparison with related work. The material necessary to perform (and replicate) the experimental evaluation is the following:

  • Jar executable file of the NEW implementation of swget based in multithread (this version is referred to as swgetM) . This new implementation will be the core of the swget portal. The jar can be downloaded here.
  • Jar executable file of the SQUIN system (version  0.1.4). SQUIN has been downloaded from http://squin.org. The SQUIN jar file used in the evaluation can be downloaded here.
  • Jar executable file to query remote SPARQL endpoints programmatically via Jena. The jar can be downloaded here.
  • Files containing the queries used in the experiments for the above three systems. The files can be downloaded here.

Note that since SQUIN does not support expressions with repetitions we implemented a translator from NautiLOD expression to SQUIN queries. Moreover, SQUIN guarantees results only for a subset of SPARQL 1.0 (only BGPs). For other complex types of queries (e.g., involving union) the system does not guarantee completeness of the results. Last but not least there is a substantial difference between NautiLOD/swget and SQUIN. SQUIN implements the Link-Traversal-Based Query Execution approach (LTBQE) by using non-blocking iterators. This means that SQUIN cannot guarantee to discover all reachable URIs that may contribute to the final results (more detail available at [H2012]).

[H2012] O. Hartig: SPARQL for a Web of Linked Data: Semantics and Computability, ESWC , pp. 8-23, 2012.

Experimental setting:

Usage of the swgetM jar file: java -jar swgetm.jar seed_uri_file query_file_name OPTIONS

  • -stream: streams the results as they are available (default=false)
  • -t: sets the number of threads to be used (default=5)
  • -b: sets the budget in terms of maximum number of dereferencing operations allowed (defaul=no bound)
  • -noM: does not cache Jena models obtained from URI dereferencing

Example: 

java -jar swgetm.jar ./queryset/swget/influences/tbl-infl-seed.dat ./queryset/swget/influences/tbl-infl-scient-dist3.dat

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Usage of the squin jar file: java -jar squin.jar seed_uri_file query_file_name

Example:

java -jar squin.jar ./queryset/squin/influences/tbl-infl-seed.dat ./queryset/squin/influences/tbl-infl-scient-dist3.dat

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Usage of the sparql1-1.jar file:

java -jar sparql1-1.jar endpoint_address query_file_name