What is SPARQL endpoint?

What is SPARQL endpoint?

A SPARQL Endpoint is a Point of Presence on an HTTP network that’s capable of receiving and processing SPARQL Protocol requests. It is identified by a URL commonly referred to as a SPARQL Endpoint URL.

What is FOAF in SPARQL?

Dataset: Friend of a Friend (FOAF) FOAF is a standard RDF vocabulary for describing people and relationships. Tim Berners-Lee’s FOAF information available at http://www.w3.org/People/Berners-Lee/card.

What is query structure in SPARQL?

Structure of a SPARQL Query A SPARQL query comprises, in order: Prefix declarations, for abbreviating URIs. Dataset definition, stating what RDF graph(s) are being queried. A result clause, identifying what information to return from the query. The query pattern, specifying what to query for in the underlying dataset.

What is the difference between SPARQL and SQL?

In considering the differences, it is important to keep in mind that SPARQL is designed to query RDF data while SQL is designed to query relational data. As such, both languages and their respective advantages closely reflect the data models they work with.

Can a SPARQL endpoint be used by applications as well?

In chapter 3 we looked at other ways in which Linked Data can be made available in order to be consumed by an application. As well as providing a SPARQL endpoint, RDF data can be accessed by dereferencing HTTP URIs, parsing RFDa or reading an RDF dump.

Where is SPARQL used?

SPARQL can be used to express queries across diverse data sources, whether the data is stored natively as RDF or viewed as RDF via middleware. SPARQL contains capabilities for querying required and optional graph patterns along with their conjunctions and disjunctions.

What types of queries does SPARQL support select all that apply?

SPARQL allows for a query to consist of triple patterns, conjunctions, disjunctions, and optional patterns. Implementations for multiple programming languages exist. There exist tools that allow one to connect and semi-automatically construct a SPARQL query for a SPARQL endpoint, for example ViziQuer.

What can you do with SPARQL?

SPARQL, short for “SPARQL Protocol and RDF Query Language”, enables users to query information from databases or any data source that can be mapped to RDF. The SPARQL standard is designed and endorsed by the W3C and helps users and developers focus on what they would like to know instead of how a database is organized.

How do I query RDF using SPARQL?

2.5 Building RDF Graphs SPARQL has several query forms. The SELECT query form returns variable bindings. The CONSTRUCT query form returns an RDF graph. The graph is built based on a template which is used to generate RDF triples based on the results of matching the graph pattern of the query.

What types of queries does SPARQL support?

SPARQL also supports aggregation, subqueries, negation, creating values by expressions, extensible value testing, and constraining queries by source RDF graph. The results of SPARQL queries can be result sets or RDF graphs.

What is regex in SPARQL?

SPARQL provides an operation to test strings, based on regular expressions. This includes the ability to ask SQL “LIKE” style tests, although the syntax of the regular expression is different from SQL. The syntax is: FILTER regex(?x, “pattern” [, “flags”])

What is a SPARQL service endpoint?

SPARQL Service Endpoint- A site such as the Virtuouso SPARQL Query Demothat handles and returns the SPARQL queries through http. A SPARQL endpointcan either be “generic” or “specific,” meaning that they can either accept any RDF dataset URI that is specified for the query, or they are hardwired to only use one specific RDF dataset.

What does SPARQL stand for?

SPARQL (pronounced ” sparkle ” / ˈspɑːkəl /, a recursive acronym for SPARQL Protocol and RDF Query Language) is an RDF query language —that is, a semantic query language for databases —able to retrieve and manipulate data stored in Resource Description Framework (RDF) format.

What is a federated query in SPARQL?

SPARQL. This query can be distributed to multiple SPARQL endpoints (services that accept SPARQL queries and return results), computed, and results gathered, a procedure known as federated query . Whether in a federated manner or locally, additional triple definitions in the query could allow joins to different subject types, such as automobiles,…

What is the SPARQL extension for RDF?

SPARUL is another extension to SPARQL. It enables the RDF store to be updated with this declarative query language, by adding INSERT and DELETE methods. See List of SPARQL implementations for more comprehensive coverage, including triplestore, APIs, and other storages that have implemented the SPARQL standard.