Understands the use of SPARQL functions and operators. – Linked Data for Professional Education

Don’t Use a Hammer to Screw in a Nail: Alternatives to REGEX in SPARQL

Sun, 13 Aug 2017 08:18:11 +0000

This brief blog post explains that regular expressions are expensive to evaluate regardless of what language you are using them in. The author suggests that if you can avoid using a regular expression in favor of a simpler string computation, then you can likely get much better performance out of your SPARQL engine. Alternative strategies include using CONTAINS, LCASE, UCASE, STRSTARTS, and STRENDS. If more complex string operations are required, full-text extensions to the SPARQL engine may be an option.

URL: http://www.cray.com/blog/dont-use-hammer-screw-nail-alternatives-regex-sparql/
Keywords: SPARQL, CONTAINS, String operations, REGEX, Jena Text
Author: Vesse, Rob
Publisher: Cray
Date created: 2014-06-03 04:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P10M
Educational use: instruction
Educational audience: student
Interactivity type: expositive

Equality and Inequality in SPARQL

Sun, 13 Aug 2017 08:18:11 +0000

This brief blog post discusses issues surrounding expression semantics in SPARQL. Practices that people are used to from other languages (like the use of "=" and "!="), can often be confusing to new – and even not so new- SPARQL developers. The author suggests that an awareness of type errors will allow the user to understand what is occurring. Example queries show how type errors are treated when using FILTER. An alternative method involving project expressions or BIND is proposed.

URL: http://www.cray.com/blog/equality-inequality-sparql/
Keywords: SPARQL, BIND, FILTER, Type errors, Project expressions
Author: Vesse, Rob
Publisher: Cray
Date created: 2013-04-23 04:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P10M
Educational use: instruction
Educational audience: student
Interactivity type: expositive

Jena Full Text Search

Sun, 13 Aug 2017 08:18:11 +0000

This documentation explains how to configure and use the Full Text extension to Apache Jena's ARQ (the module is included in Fuseki). The extension combines SPARQL and full-text search via Lucene or ElasticSearch (built on Lucene). It gives applications the ability to perform indexed full-text searches within SPARQL queries. Although SPARQL allows the use of regular expressions in FILTER, this is a test on a value retrieved earlier in the query and its use is not indexed. In other words, if you're searching for occurrences of a specific term in the rdfs:label of a bunch of products, then the search will need to examine all selected rdfs:label statements and apply the regular expression to each label in turn. If there are many such statements and many such uses of regex, then it may be appropriate to consider using this extension to take advantage of the performance potential of full text indexing.

URL: http://jena.apache.org/documentation/query/text-query.html
Keywords: SPARQL, REGEX, FILTER, Apache Jena
Publisher: Apache Jena
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P2H
Educational use: professionalDevelopment

SPARQL and Linked Data Homework Exercises

Sat, 21 Jan 2017 06:46:40 +0000

This document contains several "written" and "electronic" homework questions originally from the course "Semantic Web Topics" at LeHigh University. They include: Write a series of SPARQL queries using a provided schema; Write a SPARQL construct query that generates all triples inferred by a specific RDFS entailment rule; Write a SPARQL construct query to generate
owl:sameAs statements between domains which share specified property; Describe the pros and cons of generating links in the manner specified in the previous question; Using Jena, create a class that can read in all the files in a specified directory and create a Web page that lists a series of publications organized by topic – reading all of the files into a single model and only using SPARQL to retrieve information from the model.

URL: http://www.cse.lehigh.edu/~heflin/courses/sw-2013/hw2.pdf
Keywords: SPARQL, RDF Schema, Entailment regime, Apache Jena, Java
Author: Heflin, Jeff
Date created: 2013-02-01 05:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P4H
Educational use: assessment
Educational audience: teacher-educationSpecialist
Interactivity type: active

All Roads Lead To? Experiments With Gephi, Linked Data and Wikipedia

Sat, 14 Jan 2017 06:46:01 +0000

This blog post shares an example using the Semantic Web Import plugin (available for the Gephi visualization tool) to create a rather complex geospatial visualization. This tutorial also includes good information on how to explore a dataset using SPARQL queries and how to filter query results to "clean-up" DBpedia data so that it is more suitable for use.

URL: https://johngoodwin225.wordpress.com/2014/03/26/all-roads-lead-to-experiments-with-gephi-linked-data-and-wikipedia/
Keywords: Gephi, DBpedia, Geospatial data, SPARQL
Author: Goodwin, John
Date created: 2014-03-26 04:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P20M

SPARQL: Using Operators Tutorial and Quiz

Thu, 24 Nov 2016 05:51:17 +0000

This slide tutorial focuses on using various operators in SPARQL queries. Several examples are provided which include the RDF data being queried, the SPARQL query itself, and the result table. This is followed by quiz questions which ask the user to query DBpedia's SPARQL endpoint. The answers to the question (in the form of completed SPARQL queries) are included.

URL: http://skkudatalab.weebly.com/sparql-operators.html
Keywords: DBpedia, SPARQL
Author: Oh, Sam
Publisher: Sungkyunkwan University (SKKU)
Date created: 2016-11-22 05:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P40M
Educational use: instruction
Educational audience: professional
Interactivity type: expositive

Foundations of RDF Databases

Abi Evans — Thu, 10 Mar 2016 04:09:00 +0000

This older presentation presents the argument that the RDF data model can be viewed as an extension of the traditional database model, rather than as a new technology replacing it. Provides a great deal of coverage on SPARQL as well, including how queries are built using operators. Discusses the role of logic and semantics in working with RDF and SPARQL.

URL: http://videolectures.net/eswc08_gutierrez_frdf/
Keywords: SPARQL, Triple, SQL, Relational model, RDBMS
Author: Gutierrez, Claudio
Date created: 2008-08-08 04:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P1H25M

SPARQL Queries for Publications and Authors

Sat, 16 Jan 2016 13:43:29 +0000

This page contains SPARQL queries useful for finding information on authors and publications on VIVO. These query examples, if adapted, have other useful applications as well.

URL: https://wiki.duraspace.org/display/VIVO/SPARQL+Queries+for+Publications+and+Authors
Keywords: SPARQL, VIVO
Author: Rejack, Nicholas
Publisher: Duraspace
Date created: 2014-04-02 04:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P10M
Educational use: professionalDevelopment
Educational audience: professional
Interactivity type: mixed

Toward the Web of Functions: Interoperable High-Order Functions in SPARQL

Sat, 16 Jan 2016 13:43:29 +0000

This video addresses the problem needing to know the specific URI of any third-party custom SPARQL function in order for the computation to be executed on the remote endpoint that defines and implements the function. Presented is a standard-compliant solution that does not require changes to the current syntax or semantics of the language, based on the use of a call function.

URL: http://videolectures.net/iswc2014_atzori_web_of_functions/
Keywords: Interoperability, Functions, SPARQL, Expressivity, SPARQL endpoint
Author: Atzori, Maurizio
Date created: 2014-12-19 05:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P15M

Querying the Linked Archives Hub data using SPARQL

Sat, 16 Jan 2016 13:43:28 +0000

This blog post provides a few sample SPARQL queries that can be used as a starting point for exploring an unfamiliar dataset. The queries are intended to give users an idea of what is possible and a platform to build on. The dataset used in these examples is LOCAH archival data which, like most archives, is hierarchically organized into collection level and sub-levels.

URL: http://locah.archiveshub.ac.uk/tag/sparql/
Keywords: Archives, Dataset, RDF, SPARQL endpoint, SPARQL
Author: Petej
Publisher: LOCAH Project
Date created: 2011-05-10 04:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P30M