@inproceedings{buil-etal-2014iswc,
	title = {Strategies for Executing Federated Queries in {SPARQL1.1}},
        abstract = {A common way for exposing RDF data on the Web is by means of SPARQL endpoints, i.e., Web services that implement the SPARQL protocol and allow end users and applications to query just the RDF data they want. However, servers hosting SPARQL endpoints typically restrict the access to the data by limiting the amount of results returned by user queries or the amount of queries per time and client that may be issued. For addressing these problems we analysed different strategies that shall allow to obtain complete query results for federated queries using SPARQL1.1's federated query extension
by rewriting the original query. We show that some seemingly intuitive ``recipes'' for decomposing federated queries to circumvent server limitations provide unsound results in the general case, and provide fixes or discuss under which restrictions these recipes are still applicable. Finally, we evaluate the different proposed strategies in order to check their feasibility in practice.},
        author = {Carlos Buil-Aranda and Axel Polleres and J{\"u}rgen Umbrich},
        Booktitle = {Proceedings of the 13th International Semantic Web Conference (ISWC 2014)},
	Day = {19--23},
	Month = oct,
	Publisher = {Springer},
	Series = LNCS,
	Type = CONF,
        url = {http://www.polleres.net/publications/buil-etal-2014iswc.pdf},
	Year = 2014,
}

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For addressing these problems we analysed different strategies that shall allow to obtain complete query results for federated queries using SPARQL1.1's federated query extension by rewriting the original query. We show that some seemingly intuitive ``recipes'' for decomposing federated queries to circumvent server limitations provide unsound results in the general case, and provide fixes or discuss under which restrictions these recipes are still applicable. Finally, we evaluate the different proposed strategies in order to check their feasibility in practice.","author":[{"firstnames":["Carlos"],"propositions":[],"lastnames":["Buil-Aranda"],"suffixes":[]},{"firstnames":["Axel"],"propositions":[],"lastnames":["Polleres"],"suffixes":[]},{"firstnames":["Jürgen"],"propositions":[],"lastnames":["Umbrich"],"suffixes":[]}],"booktitle":"Proceedings of the 13th International Semantic Web Conference (ISWC 2014)","day":"19–23","month":"October","publisher":"Springer","series":"Lecture Notes in Computer Science (LNCS)","url":"http://www.polleres.net/publications/buil-etal-2014iswc.pdf","year":"2014","bibtex":"@inproceedings{buil-etal-2014iswc,\n\ttitle = {Strategies for Executing Federated Queries in {SPARQL1.1}},\n abstract = {A common way for exposing RDF data on the Web is by means of SPARQL endpoints, i.e., Web services that implement the SPARQL protocol and allow end users and applications to query just the RDF data they want. However, servers hosting SPARQL endpoints typically restrict the access to the data by limiting the amount of results returned by user queries or the amount of queries per time and client that may be issued. For addressing these problems we analysed different strategies that shall allow to obtain complete query results for federated queries using SPARQL1.1's federated query extension\nby rewriting the original query. We show that some seemingly intuitive ``recipes'' for decomposing federated queries to circumvent server limitations provide unsound results in the general case, and provide fixes or discuss under which restrictions these recipes are still applicable. 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