Copyright © 2013 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.
The SPARQL Protocol and RDF Query Language (SPARQL) is a query language and protocol for RDF. This document specifies the SPARQL Protocol; it describes a means for conveying SPARQL queries and updates to a SPARQL processing service and returning the results via HTTP to the entity that requested them. This protocol was developed by the W3C SPARQL Working Group, part of the Semantic Web Activity as described in the activity statement .
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This document is one of eleven SPARQL 1.1 Proposed Recommendations:
The W3C Director seeks review and feedback from W3C Advisory Committee representatives, via their review form by 26 February 2013. This will allow the Director to assess consensus and determine whether to issue this document as a W3C Recommendation.
Others are encouraged by the SPARQL Working Group to continue to send reports of implementation experience, and other feedback, to public-rdf-dawg-comments@w3.org (public archive). Reports of any success or difficulty with the test cases are encouraged. Open discussion among developers is welcome at public-sparql-dev@w3.org (public archive).
The advancement of this Proposed Recommendation is supported by the disposition of comments on the previous drafts, the Test Suite, and the list of implementations (with test results).
Publication as a Proposed Recommendation does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
1 Introduction
1.1 Document Conventions
1.2 Terminology
2 SPARQL Protocol Operations
2.1 query operation
2.1.1 query via GET
2.1.2 query via POST with URL-encoded parameters
2.1.3 query via POST directly
2.1.4 Specifying an RDF Dataset
2.1.5 Accepted Response Formats
2.1.6 Success Responses
2.1.7 Failure Responses
2.2 update operation
2.2.1 update via POST with URL-encoded parameters
2.2.2 update via POST directly
2.2.3 Specifying an RDF Dataset
2.2.4 Success Responses
2.2.5 Failure Responses
2.3 Determining the Base IRI
3 Example SPARQL Protocol Requests (informative)
3.1 Examples of SPARQL Query
3.1.1 SELECT with service-supplied RDF Dataset
3.1.2 SELECT with simple RDF Dataset
3.1.3 CONSTRUCT with simple RDF
dataset and HTTP content negotiation
3.1.4 ASK with simple RDF Dataset
3.1.5 DESCRIBE with simple RDF Dataset
3.1.6 SELECT with complex RDF Dataset
3.1.7 SELECT with query-only RDF Dataset
3.1.8 SELECT with ambiguous RDF Dataset
3.1.9 SELECT with malformed query fault
3.1.10 SELECT with query request refused fault
3.1.11 Long SELECT query using POST with URL encoding
3.1.12 Long SELECT query using direct POST
3.1.13 SELECT with internationalization
3.2 Examples of SPARQL Update
3.2.1 UPDATE using URL-encoded parameters
3.2.2 UPDATE using POST directly
3.2.3 UPDATE specifying dataset and using POST directly
3.2.4 Multi-operation UPDATE using URL-encoded parameters
3.2.5 Multi-operation UPDATE specifying dataset and using URL-encoded parameters
3.2.6 Multi-operation UPDATE specifying dataset and using POST directly
4 Policy Considerations
4.1 Security
5 Conformance
6 Changes Since Previous Recommendation (Informative)
A References
A.1 Normative References
A.2 Other References
This document describes the SPARQL 1.1 Protocol, a means of conveying SPARQL queries and updates from clients to SPARQL processors. The SPARQL Protocol has been designed for compatibility with the SPARQL 1.1 Query Language [SPARQL] and with the SPARQL 1.1 Update Language for RDF. This document is primarily intended for software developers interested in implementing SPARQL query and update services and clients.
The SPARQL Protocol consists of two HTTP operations: a query operation for performing SPARQL Query Language queries and an update operation for performing SPARQL Update Language requests. SPARQL Protocol clients send HTTP requests to SPARQL Protocol services that handle the request and send HTTP responses back to the originating client.
A separate document describes the SPARQL 1.1 Graph Store HTTP Protocol which describes the use of HTTP operations for the purpose of managing a collection of graphs in the REST architectural style.
When this document uses the words must, must not, should, should not, may and recommended, and the words appear as emphasized text, they must be interpreted as described in RFC 2119 [RFC2119].
The SPARQL Protocol consists of two operations: query and update. A protocol operation defines combinations of:
The SPARQL 1.1 Protocol is built on top of HTTP. All HTTP requirements for requests and responses must be followed.
query
operation
The query
operation is used to send a SPARQL query
to a service and receive the results of the query. The query
operation MUST be invoked with either the HTTP
GET or HTTP POST method. Client requests for this operation must include
exactly one SPARQL query string (parameter name:
query
) and may include
zero or more default graph URIs (parameter name:
default-graph-uri
) and named graph URIs (parameter
name: named-graph-uri
). The
response to a query request is either the SPARQL XML Results
Format, the SPARQL JSON Results Format, the SPARQL CSV/TSV Results Format, or an RDF
serialization, depending on the query form [SPARQL] and content
negotiation [RFC2616].
HTTP Method | Query String Parameters | Request Content Type | Request Message Body | |
---|---|---|---|---|
query via GET | GET | query (exactly 1)default-graph-uri (0 or more)named-graph-uri (0 or more) | None | None |
query via URL-encoded POST | POST | None | application/x-www-form-urlencoded | URL-encoded, ampersand-separated query parameters.query (exactly 1)default-graph-uri (0 or more)named-graph-uri (0 or more) |
query via POST directly | POST | default-graph-uri (0 or more)named-graph-uri (0 or more) | application/sparql-query | Unencoded SPARQL query string |
The query
request's parameters must be sent
according to one of these three options:
query
via GETProtocol clients may send protocol requests via the HTTP GET method. When using the GET method, clients must URL percent encode all parameters and include them as query parameter strings with the names given above [RFC3986].
HTTP query string parameters must be separated with
the ampersand (&
) character. Clients may include
the query string parameters in any order.
The HTTP request MUST NOT include a message body.
query
via POST with URL-encoded parameters
Protocol clients may send protocol requests via
the HTTP POST method by URL encoding the parameters. When using
this method, clients must URL percent encode [RFC3986] all
parameters and include them as parameters within the request body
via the application/x-www-form-urlencoded
media type
with the name given above.
Parameters must be separated with
the ampersand (&
) character. Clients may include
the parameters in any order. The content type header of the HTTP
request must be set to
application/x-www-form-urlencoded
.
query
via POST directly
Protocol clients may send protocol requests via
the HTTP POST method by including the query directly and unencoded
as the HTTP request message body. When using this approach, clients
must include the SPARQL query string, unencoded,
and nothing else as the message body of the request. Clients
must set the content type header of the HTTP
request to application/sparql-query
. Clients
may include the optional
default-graph-uri
and named-graph-uri
parameters as HTTP query string parameters in the request URI. Note that UTF-8 is the only valid charset here.
A SPARQL query is executed against an RDF
Dataset. The RDF Dataset for a query may be specified either via the
default-graph-uri
and named-graph-uri
parameters in the SPARQL Protocol or in the SPARQL query string using
the FROM
and FROM NAMED
keywords.
If different RDF Datasets are specified in both the protocol request and the
SPARQL query string, then the SPARQL service must
execute the query using the RDF Dataset given in the protocol request.
Note that a service may reject a query with HTTP response code 400 if the service does not allow protocol clients to specify the RDF Dataset.
If an RDF Dataset is not specified in either the protocol request or the SPARQL query string, then implementations may execute the query against an implementation-defined default RDF dataset.
Protocol clients should use HTTP content negotiation [RFC2616] to request response formats that the client can consume. See below for more on potential response formats.
The SPARQL Protocol uses the response status codes defined in HTTP to indicate the success or failure of an operation. Consult the HTTP specification [RFC2616] for detailed definitions of each status code. While a protocol service should use a 2XX HTTP response code for a successful query, it may choose instead to use a 3XX response code as per HTTP.
The response body of a successful query operation with a 2XX response is either:
The content type of the response to a successful query operation must be the media type defined for the format of the response body.
The HTTP response codes applicable to an unsuccessful query operation include:
The response body of a failed query request is implementation defined. Implementations may use HTTP content negotiation to provide human-readable or machine-processable (or both) information about the failed query request.
A protocol service may use other 4XX or 5XX HTTP response codes for other failure conditions, as per HTTP.
update
operation
The update
operation is used to send a SPARQL update
request to a service. The
update operation must be invoked using the HTTP POST
method.
Client requests for this operation must include
exactly one SPARQL update request string (parameter name:
update
) and may include
zero or more default graph URIs (parameter name:
using-graph-uri
) and named graph URIs (parameter
name: using-named-graph-uri
). The
response to an update request indicates success or failure of the
request via HTTP response status code.
HTTP Method | Query String Parameters | Request Content Type | Request Message Body | |
---|---|---|---|---|
update via URL-encoded POST | POST | None | application/x-www-form-urlencoded | URL-encoded, ampersand-separated query parameters.update (exactly 1)using-graph-uri (0 or more)using-named-graph-uri (0 or more) |
update via POST directly | POST | using-graph-uri (0 or more)using-named-graph-uri (0 or more) | application/sparql-update | Unencoded SPARQL update request string |
The update
request's parameters must be sent
according to one of these two options:
update
via POST with URL-encoded parameters
Protocol clients may send update protocol requests via
the HTTP POST method by URL encoding the parameters. When using
this approach, clients must URL percent encode [RFC3986] all
parameters and include them as parameters within the request body
via the application/x-www-form-urlencoded
media type
with the name given above.
Parameters must be separated with
the ampersand (&
) character. Clients may include
the parameters in any order. The content type header of the HTTP
request must be set to
application/x-www-form-urlencoded
.
update
via POST directly
Protocol clients may send update protocol requests via
the HTTP POST method by including the update request directly and unencoded
as the HTTP request message body. When using this approach, clients
must include the SPARQL update request string, unencoded,
and nothing else as the message body of the request. Clients
must set the content type header of the HTTP
request to application/sparql-update
. Clients
may include the optional
using-graph-uri
and using-named-graph-uri
parameters as HTTP query string parameters in the request URI.
SPARQL Update requests are executed against a Graph Store, a mutable container of RDF graphs managed by a SPARQL service. The WHERE
clause of a SPARQL update DELETE/INSERT operation [UPDATE]
matches against data in an RDF
Dataset, which is a subset of the Graph Store. The RDF Dataset for an update operation may be specified
either in the operation string itself
using the USING
, USING NAMED
, and/or WITH
keywords, or it may be specified via the
using-graph-uri
and using-named-graph-uri
parameters.
It is an error to supply the using-graph-uri
or using-named-graph-uri
parameters
when using this protocol to convey a SPARQL 1.1 Update request that contains an operation that uses the
USING
, USING NAMED
, or WITH
clause.
A SPARQL Update processor should treat each occurrence of the using-graph-uri=g
parameter in an
update protocol operation as if a USING <g>
clause were included for every operation in the SPARQL 1.1
Update request. Similarly, a SPARQL Update processor should treat each occurrence of the using-named-graph-uri=g
parameter in an update protocol operation as if a USING NAMED <g>
clause were included for every operation in
the SPARQL 1.1 Update request.
The SPARQL Protocol uses the response status codes defined in HTTP to indicate the success or failure of an operation. Consult the HTTP specification [RFC2616] for detailed definitions of each status code. While a protocol service should use a 2XX HTTP response code for an update request that is successfully processed, it may choose instead to use a 3XX response code as per HTTP.
The response body of a successful update request is implementation defined. Implementations may use HTTP content negotiation to provide both human-readable and machine-processable information about the completed update request.
The HTTP response code for an unsuccessful update request should be:
The response body of a failed update request is implementation defined. Implementations may use HTTP content negotiation to provide human-readable or machine-processable (or both) information about the failed update request.
A protocol service may use other 4XX or 5XX HTTP response codes for other failure conditions, as per HTTP.
The BASE
keyword in a SPARQL query or a SPARQL
update request string defines the Base IRI used to resolve relative
IRIs per Uniform
Resource Identifier (URI): Generic Syntax [RFC3986] section 5.1.1, "Base URI Embedded in
Content".
The SPARQL Protocol
does not dereference query URIs so section 5.1.3 does not apply.
Finally, per section 5.1.4, SPARQL Protocol services must define their
own base URI, which may be the service endpoint.
The following HTTP trace examples illustrate invocation of the
query
and update
operations under several different scenarios. Some example traces are abstracted from complete HTTP traces in these ways:
query
operation examples, only partial response bodies, containing the query results, are displayed.This SPARQL query
PREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT ?book ?who WHERE { ?book dc:creator ?who }
is conveyed via HTTP GET to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=PREFIX%20dc%3A%20%3Chttp%3A%2F%2Fpurl.org%2Fdc%2Felements%2F1.1%2F%3E%20%0ASELECT%20%3Fbook%20%3Fwho%20%0AWHERE%20%7B%20%3Fbook%20dc%3Acreator%20%3Fwho%20%7D%0A HTTP/1.1 Host: www.example User-agent: my-sparql-client/0.1
That query against the service-supplied RDF Dataset, executed by that SPARQL query service, returns the following query result:
HTTP/1.1 200 OK Date: Fri, 06 May 2005 20:55:12 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: application/sparql-results+xml <?xml version="1.0"?> <sparql xmlns="http://www.w3.org/2005/sparql-results#"> <head> <variable name="book"/> <variable name="who"/> </head> <results> <result> <binding name="book"><uri>http://www.example/book/book5</uri></binding> <binding name="who"><bnode>r29392923r2922</bnode></binding> </result> ... </sparql>
This SPARQL query
PREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT ?book ?who WHERE { ?book dc:creator ?who }
is conveyed to the SPARQL query service, http://www.other.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=PREFIX%20dc%3A%20%3Chttp%3A%2F%2Fpurl.org%2Fdc%2Felements%2F1.1%2F%3E%20%0ASELECT%20%3Fbook%20%3Fwho%20%0AWHERE%20%7B%20%3Fbook%20dc%3Acreator%20%3Fwho%20%7D%0A&default-graph-uri=http%3A%2F%2Fwww.other.example%2Fbooks HTTP/1.1 Host: www.other.example User-agent: my-sparql-client/0.1
That query — against the RDF Dataset identified by the value
of the default-graph-uri
parameter, http://www.other.example/books — executed
by that SPARQL query service, returns the following query
result:
HTTP/1.1 200 OK Date: Fri, 06 May 2005 20:55:12 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: application/sparql-results+xml <?xml version="1.0"?> <sparql xmlns="http://www.w3.org/2005/sparql-results#"> <head> <variable name="book"/> <variable name="who"/> </head> ... </sparql>
This SPARQL query
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX myfoaf: <http://www.example/jose/foaf.rdf#> CONSTRUCT { myfoaf:jose foaf:depiction <http://www.example/jose/jose.jpg>. myfoaf:jose foaf:schoolHomepage <http://www.edu.example/>. ?s ?p ?o.} WHERE { ?s ?p ?o. myfoaf:jose foaf:nick "Jo". FILTER ( ! (?s = myfoaf:kendall && ?p = foaf:knows && ?o = myfoaf:edd ) && ! ( ?s = myfoaf:julia && ?p = foaf:mbox && ?o = <mailto:julia@mail.example> ) && ! ( ?s = myfoaf:julia && ?p = rdf:type && ?o = foaf:Person)) }
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=EncodedQuery&default-graph-uri=http%3A%2F%2Fwww.example%2Fjose-foaf.rdf HTTP/1.1 Host: www.example User-agent: sparql-client/0.1 Accept: text/turtle, application/rdf+xml
With the response illustrated here:
HTTP/1.1 200 OK Date: Fri, 06 May 2005 20:55:11 GMT Server: Apache/1.3.29 (Unix) Connection: close Content-Type: text/turtle @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>. @prefix foaf: <http://xmlns.com/foaf/0.1/>. @prefix myfoaf: <http://www.example/jose/foaf.rdf#>. myfoaf:jose foaf:name "Jose Jimeñez"; foaf:depiction <http://www.example/jose/jose.jpg>; foaf:nick "Jo"; ...
Note: registration for the media type text/turtle was started but not completed at the time of this publication. Please see http://www.w3.org/TR/turtle for the final registered media type for the Turtle language.
This SPARQL query
PREFIX dc: <http://purl.org/dc/elements/1.1/> ASK WHERE { ?book dc:creator "J.K. Rowling"}
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=EncodedQuery&default-graph-uri=http%3A%2F%2Fwww.example%2Fbooks HTTP/1.1 Host: www.example User-agent: sparql-client/0.1
With the response illustrated here:
HTTP/1.1 200 OK Date: Fri, 06 May 2005 20:48:25 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: application/sparql-results+xml <?xml version="1.0"?> <sparql xmlns="http://www.w3.org/2005/sparql-results#"> <head></head> <boolean>true</boolean> </sparql>
This SPARQL query
PREFIX books: <http://www.example/book/> DESCRIBE books:book6
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated here:
GET /sparql/?query=EncodedQuery&default-graph-uri=http%3A%2F%2Fwww.example%2Fbooks HTTP/1.1 Host: www.example User-agent: sparql-client/0.1
With the response illustrated here:
HTTP/1.1 200 OK Date: Wed, 03 Aug 2005 12:48:25 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: application/rdf+xml <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:books="http://www.example/book/" xmlns:dc="http://purl.org/dc/elements/1.1/" > <rdf:Description rdf:about="http://www.example/book/book6"> <dc:title>Example Book #6 </dc:title> </rdf:Description> </rdf:RDF>
This SPARQL query
PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT ?who ?g ?mbox WHERE { ?g dc:publisher ?who . GRAPH ?g { ?x foaf:mbox ?mbox } }
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated here (with line breaks for legibility):
GET /sparql/?query=EncodedQuery&default-graph-uri=http%3A%2F%2Fwww.example%2Fpublishers &default-graph-uri=http%3A%2F%2Fwww.example%2Fmorepublishers&named-graph-uri=http%3A%2F%2Fyour.example%2Ffoaf-alice &named-graph-uri=http%3A%2F%2Fwww.example%2Ffoaf-bob&named-graph-uri=http%3A%2F%2Fwww.example%2Ffoaf-susan &named-graph-uri=http%3A%2F%2Fthis.example%2Fjohn%2Ffoaf Host: www.example User-agent: sparql-client/0.1
With the response illustrated here:
HTTP/1.1 200 OK Date: Wed, 03 Aug 2005 12:48:25 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: application/sparql-results+xml <?xml version="1.0"?> <sparql xmlns="http://www.w3.org/2005/sparql-results#"> <head> <variable name="who"/> <variable name="g"/> <variable name="mbox"/> </head> ... </sparql>
This SPARQL query
PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT ?who ?g ?mbox FROM <http://www.example/publishers> FROM NAMED <http://www.example/alice> FROM NAMED <http://www.example/bob> WHERE { ?g dc:publisher ?who . GRAPH ?g { ?x foaf:mbox ?mbox } }
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=EncodedQuery HTTP/1.1 Host: www.example User-agent: sparql-client/0.1
With the response illustrated here:
HTTP/1.1 200 OK Date: Wed, 03 Aug 2005 12:48:25 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: application/sparql-results+xml <?xml version="1.0"?> <sparql xmlns="http://www.w3.org/2005/sparql-results#"> ... </sparql>
This SPARQL query
PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT ?who ?g ?mbox FROM <http://www.example/publishers> FROM NAMED <http://www.example/john> FROM NAMED <http://www.example/susan> WHERE { ?g dc:publisher ?who . GRAPH ?g { ?x foaf:mbox ?mbox } }
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=EncodedQuery&default-graph-uri=http%3A%2F%2Fwww.example%2Fmorepublishers &named-graph-uri=http%3A%2F%2Fwww.example%2Fbob&named-graph-uri=http%3A%2F%2Fwww.example%2Falice HTTP/1.1 Host: www.example User-agent: sparql-client/0.1
This protocol operation contains an ambiguous RDF Dataset: the dataset specified in the query is different than the one
specified in the protocol (by way of default-graph-uri
and named-graph-uri
parameters). A
conformant SPARQL Protocol service must resolve this ambiguity by executing the query against the RDF Dataset specified in
the protocol:
HTTP/1.1 200 OK Date: Wed, 03 Aug 2005 12:48:25 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: application/sparql-results+xml <?xml version="1.0"?> <sparql xmlns="http://www.w3.org/2005/sparql-results#"> <head> <variable name="who"/> <variable name="g"/> <variable name="mbox"/> </head> <results> <result> <binding name="who"> <literal>Bob Hacker</literal> </binding> <binding name="g"> <uri>http://www.example/bob</uri> </binding> <binding name="mbox"> <uri>mailto:bob@oldcorp.example</uri> </binding> </result> <result> <binding name="who"> <literal>Alice Hacker</literal> </binding> <binding name="g"> <uri>http://www.example/alice</uri> </binding> <binding name="mbox"> <uri>mailto:alice@work.example</uri> </binding> </result> </results> </sparql>
This syntactically invalid SPARQL query
PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?name WHERE { ?x foaf:name ?name ORDER BY ?name }
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=EncodedQuery&default-graph-uri=http%3A%2F%2Fwww.example%2Fmorepublishers HTTP/1.1 Host: www.example User-agent: sparql-client/0.1
With the error response illustrated here:
HTTP/1.1 400 Bad Request Date: Wed, 03 Aug 2005 12:48:25 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: text/plain; charset=UTF-8 4:syntax error, unexpected ORDER, expecting '}'
This SPARQL query
PREFIX bio: <http://bio.example/schema/#> SELECT ?valence FROM <http://another.example/protein-db.rdf> WHERE { ?x bio:protein ?valence } ORDER BY ?valence
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=EncodedQuery&default-graph-uri=http%3A%2F%2Fanother.example%2Fprotein-db.rdf HTTP/1.1 Host: www.example User-agent: sparql-client/0.1
With the error response illustrated here:
HTTP/1.1 500 Internal Server Error Date: Wed, 03 Aug 2005 12:48:25 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: text/plain SPARQL Processing Service: Query Request Refused Your request could not be processed because http://another.example/protein-db.rdf could not be retrieved within the time alloted.
Some SPARQL queries, perhaps machine generated, may be longer than can be reliably conveyed by way of the HTTP GET binding described in 2.1.1 query via GET. In those cases the POST binding described in 2.1.2 query via POST with URL-encoded parameters may be used. This SPARQL query
PREFIX : <http://www.w3.org/2002/12/cal/icaltzd#> PREFIX Chi: <http://www.w3.org/2002/12/cal/test/Chiefs.ics#> PREFIX New: <http://www.w3.org/2002/12/cal/tzd/America/New_York#> PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> SELECT ?summary WHERE { { Chi:D603E2AC-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-09-08T16:00:00"^^New:tz; :dtstamp "2002-09-06T03:09:27Z"^^xsd:dateTime; :dtstart "2002-09-08T13:00:00"^^New:tz; :summary ?summary; :uid "D603E2AC-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D603E90B-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-09-15T16:00:00"^^New:tz; :dtstamp "2002-09-06T03:10:19Z"^^xsd:dateTime; :dtstart "2002-09-15T13:00:00"^^New:tz; :summary ?summary; :uid "D603E90B-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D603ED6E-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-09-22T16:00:00"^^New:tz; :dtstamp "2002-09-06T03:11:05Z"^^xsd:dateTime; :dtstart "2002-09-22T13:00:00"^^New:tz; :summary ?summary; :uid "D603ED6E-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D603F18C-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-09-29T16:00:00"^^New:tz; :dtstamp "2002-09-06T03:15:46Z"^^xsd:dateTime; :dtstart "2002-09-29T13:00:00"^^New:tz; :summary ?summary; :uid "D603F18C-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D603F5B7-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-11-04"^^xsd:date; :dtstamp "2002-09-06T03:12:53Z"^^xsd:dateTime; :dtstart "2002-11-03"^^xsd:date; :summary ?summary; :uid "D603F5B7-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D603F9D7-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-11-10T20:15:00"^^New:tz; :dtstamp "2002-09-06T03:14:12Z"^^xsd:dateTime; :dtstart "2002-11-10T17:15:00"^^New:tz; :summary ?summary; :uid "D603F9D7-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D604022C-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-11-17T17:00:00"^^New:tz; :dtstamp "2002-09-06T03:14:51Z"^^xsd:dateTime; :dtstart "2002-11-17T14:00:00"^^New:tz; :summary ?summary; :uid "D604022C-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D604065C-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-10-06T19:05:00"^^New:tz; :dtstamp "2002-09-06T03:16:54Z"^^xsd:dateTime; :dtstart "2002-10-06T16:05:00"^^New:tz; :summary ?summary; :uid "D604065C-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D6040A7E-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-10-13T19:15:00"^^New:tz; :dtstamp "2002-09-06T03:17:51Z"^^xsd:dateTime; :dtstart "2002-10-13T16:15:00"^^New:tz; :summary ?summary; :uid "D6040A7E-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D6040E96-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-10-20T16:00:00"^^New:tz; :dtstamp "2002-09-06T03:18:32Z"^^xsd:dateTime; :dtstart "2002-10-20T13:00:00"^^New:tz; :summary ?summary; :uid "D6040E96-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D6041270-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-10-27T17:00:00"^^New:tz; :dtstamp "2002-09-06T03:19:15Z"^^xsd:dateTime; :dtstart "2002-10-27T14:00:00"^^New:tz; :summary ?summary; :uid "D6041270-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D6041673-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-11-24T20:05:00"^^New:tz; :dtstamp "2002-09-06T03:22:09Z"^^xsd:dateTime; :dtstart "2002-11-24T17:05:00"^^New:tz; :summary ?summary; :uid "D6041673-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D6041A73-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-12-01T17:00:00"^^New:tz; :dtstamp "2002-09-06T03:22:52Z"^^xsd:dateTime; :dtstart "2002-12-01T14:00:00"^^New:tz; :summary ?summary; :uid "D6041A73-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D60421EF-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-12-08T17:00:00"^^New:tz; :dtstamp "2002-09-06T03:24:04Z"^^xsd:dateTime; :dtstart "2002-12-08T14:00:00"^^New:tz; :summary ?summary; :uid "D60421EF-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D6042660-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-12-15T20:05:00"^^New:tz; :dtstamp "2002-09-06T03:25:03Z"^^xsd:dateTime; :dtstart "2002-12-15T17:05:00"^^New:tz; :summary ?summary; :uid "D6042660-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D6042A93-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-12-22T17:00:00"^^New:tz; :dtstamp "2002-09-06T03:25:47Z"^^xsd:dateTime; :dtstart "2002-12-22T14:00:00"^^New:tz; :summary ?summary; :uid "D6042A93-C1C9-11D6-9446-003065F198AC" . } UNION { Chi:D6042EDF-C1C9-11D6-9446-003065F198AC a :Vevent; :dtend "2002-12-28T21:00:00"^^New:tz; :dtstamp "2002-09-06T03:26:51Z"^^xsd:dateTime; :dtstart "2002-12-28T18:00:00"^^New:tz; :summary ?summary; :uid "D6042EDF-C1C9-11D6-9446-003065F198AC" . } }
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
POST /sparql/ HTTP/1.1 Host: www.example User-agent: sparql-client/0.1 Content-Type: application/x-www-form-urlencoded Content-Length: 9461 query=EncodedQuery&default-graph-uri=http%3A%2F%2Fanother.example%2Fcalendar.rdf
With the response illustrated here:
HTTP/1.1 200 OK Date: Wed, 03 Aug 2005 12:48:25 GMT Server: Apache/1.3.29 (Unix) PHP/4.3.4 DAV/1.0.3 Connection: close Content-Type: application/sparql-results+xml <?xml version="1.0"?> <sparql xmlns="http://www.w3.org/2005/sparql-results#"> <head> <variable name="summary"/> </head> <results> <result> <binding name="summary"> <literal>Chiefs vs. Cleveland @ Cleveland Stadium</literal> </binding> </result> <result> <binding name="summary"> <literal>Chiefs vs. Jacksonville @ Arrowhead Stadium</literal> </binding> </result> <result> <binding name="summary"> <literal>Chiefs vs. New England @ Gillette Stadium</literal> </binding> </result> ... <result> <binding name="summary"> <literal>Chiefs vs. Oakland @ Network Associates Coliseum</literal> </binding> </result> </results> </sparql>
SPARQL queries may also be POSTed directly without URL encoding, as described in 2.1.3 query via POST directly. The same query used in the previous example is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
POST /sparql/?default-graph-uri=http%3A%2F%2Fanother.example%2Fcalendar.rdf HTTP/1.1 Host: www.example User-agent: sparql-client/0.1 Content-Type: application/sparql-query UnencodedQuery
With the same response as in the previous example.
SPARQL queries may include internationalized characters or character sets. This SPARQL query
PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX 食: <http://www.w3.org/2001/sw/DataAccess/tests/data/i18n/kanji.ttl#> SELECT ?name ?food WHERE { [ foaf:name ?name ; 食:食べる ?food ] . }
is conveyed to the SPARQL query service, http://www.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=PREFIX%20foaf%3A%20%3Chttp%3A%2F%2Fxmlns.com%2Ffoaf%2F0.1%2F%3E%0APREFIX%20%E9%A3%9F%3A%20%3Chttp%3A%2F%2Fwww.w3.org%2F2001%2Fsw%2FDataAccess%2Ftests%2Fdata%2Fi18n%2Fkanji.ttl%23%3E%0ASELECT%20%3Fname%20%3Ffood%20%0AWHERE%20%7B%20%5B%20foaf%3Aname%20%3Fname%20%3B%20%E9%A3%9F%3A%E9%A3%9F%E3%81%B9%E3%82%8B%20%3Ffood%20%5D%20.%20%7D Host: www.example User-agent: sparql-client/0.1
HTTP/1.1 200 OK Date: Wed, 03 Aug 2005 12:48:25 GMT Server: Apache/1.3.29 (Unix) Connection: close Content-Type: application/sparql-results+xml <?xml version="1.0"?> <sparql xmlns="http://www.w3.org/2005/sparql-results#"> ... </sparql>
An example request, which is a serialisation of a request sent to http://localhost:8888/test
for the query INSERT DATA { <a> <p> <b> }
is shown below using the URL-encoded parameter form.
POST /test HTTP/1.1 Host: localhost:8888 Accept: text/plain Content-Length: 62 Content-Type: application/x-www-form-urlencoded update=INSERT%20DATA%20%7B%20%3Ca%3E%20%3Cp%3E%20%3Cb%3E%20%7D
Update requests may be sent as a POST request with a
Content-Type of application/sparql-update
:
POST /test HTTP/1.1 Host: localhost:8888 Accept: */* Content-Type: application/sparql-update Content-Length: 27 INSERT DATA { <a> <p> <b> }
A dataset for an update request may be specified using the using-graph-uri
and using-named-graph-uri
parameters.
The serialisation of an example request sent to http://localhost:8888/test
and specifying a dataset with default graph http://localhost:8888/people
is shown below.
POST /test?using-graph-uri=http%3A%2F%2Flocalhost%3A8888%2Fpeople HTTP/1.1 Host: localhost:8888 Accept: */* Content-Type: application/sparql-update Content-Length: 136 PREFIX foaf: <http://xmlns.com/foaf/0.1/> DELETE { ?person ?property ?value } WHERE { ?person ?property ?value ; foaf:givenName 'Fred' }
A sequence of multiple operations may be included in a single request, separated by a ';' (semicolon).
The serialisation of an example request sent to http://localhost:8888/test
for the query
DELETE DATA { <a> <p> <old> } ; INSERT DATA { <a> <p> <new> }
is shown below using the URL-encoded parameter form.
POST /test HTTP/1.1 Host: localhost:8888 Accept: */* Content-Type: application/x-www-form-urlencoded Content-Length: 130 update=DELETE%20DATA%20%7B%20%3Ca%3E%20%3Cp%3E%20%3Cold%3E%20%7D%20%3B%0AINSERT%20DATA%20%7B%20%3Ca%3E%20%3Cp%3E%20%3Cnew%3E%20%7D
When POSTing an update request with URL-encoded parameters, the dataset parameters
using-graph-uri
and using-named-graph-uri
are specified
in the POST body with the serialized request.
The serialisation of an example request sent to http://localhost:8888/test
for the query
PREFIX foaf: <http://xmlns.com/foaf/0.1/> INSERT { GRAPH <http://localhost:8888/people> { ?person ?property ?value } } WHERE { GRAPH ?g { ?person ?property ?value ; foaf:givenName 'Fred' } }
and specifying a dataset with the named graphs http://localhost:8888/alice/foaf.rdf
and http://localhost:8888/eve/foaf.rdf
is shown below.
POST /test HTTP/1.1 Host: localhost:8888 Accept: */* Content-Type: application/x-www-form-urlencoded Content-Length: 130 using-named-graph-uri=http%3A%2F%2Flocalhost%3A8888%2Falice%2Ffoaf.rdf&using-named-graph-uri=http%3A%2F%2Flocalhost%3A8888%2Feve%2Ffoaf.rdf&update=PREFIX%20foaf%3A%20%3Chttp%3A%2F%2Fxmlns.com%2Ffoaf%2F0.1%2F%3E%0AINSERT%20%7B%20GRAPH%20%3Chttp%3A%2F%2Flocalhost%3A8888%2Fpeople%3E%20%7B%20%3Fperson%20%3Fproperty%20%3Fvalue%20%7D%20%7D%0AWHERE%20%7B%20GRAPH%20%3Fg%20%7B%20%3Fperson%20%3Fproperty%20%3Fvalue%20%3B%20foaf%3AgivenName%20%27Fred%27%20%7D%20%7D
The serialisation of an example request sent to http://localhost:8888/test
and specifying a dataset with the named graphs http://localhost:8888/alice/foaf.rdf
and http://localhost:8888/eve/foaf.rdf
is shown below.
POST /test?using-named-graph-uri=http%3A%2F%2Flocalhost%3A8888%2Falice%2Ffoaf.rdf&using-named-graph-uri=http%3A%2F%2Flocalhost%3A8888%2Feve%2Ffoaf.rdf HTTP/1.1 Host: localhost:8888 Accept: */* Content-Type: application/sparql-update Content-Length: 190 PREFIX foaf: <http://xmlns.com/foaf/0.1/> INSERT { GRAPH <http://localhost:8888/people> { ?person ?property ?value } } WHERE { GRAPH ?g { ?person ?property ?value ; foaf:givenName 'Fred' } }
There are at least two possible sources of denial-of-service attacks against SPARQL protocol services. First, under-constrained queries can result in very large numbers of results, which may require large expenditures of computing resources to process, assemble, or return. Another possible source are queries containing very complex — either because of resource size, the number of resources to be retrieved, or a combination of size and number — RDF Dataset descriptions, which the service may be unable to assemble without significant expenditure of resources, including bandwidth, CPU, or secondary storage. In some cases such expenditures may effectively constitute a denial-of-service attack. A SPARQL protocol service may place restrictions on the resources that it retrieves or on the rate at which external resources are retrieved. There may be other sources of denial-of-service attacks against SPARQL query processing services.
Since a SPARQL protocol service may make HTTP requests of other origin servers on behalf of its clients, it may be used as a vector of attacks against other sites or services. Thus, SPARQL protocol services may effectively act as proxies for third-party clients. Such services may place restrictions on the resources that they retrieve or on the rate at which external resources can be retrieved. SPARQL protocol services may log client requests in such a way as to facilitate tracing them with regard to third-party origin servers or services.
SPARQL protocol services may choose to detect these and other costly, or otherwise unsafe, queries, impose time or memory limits on queries, or impose other restrictions to reduce the service's (and other service's) vulnerability to denial-of-service attacks. They also may refuse to process such query requests.
SPARQL protocol services may remove, insert, and change underlying data via the update operation. To protect against malicious or destructive updates, implementations may choose not to implement the update operation. Alternatively, implementations may choose to use HTTP authentication mechanisms or other implementation-defined mechanisms to prevent unauthorized invocations of the update operation.
Different IRIs may have the same appearance. Characters in different scripts may look similar (a Cyrillic "о" may appear similar to a Latin "o"). A character followed by combining characters may have the same visual representation as another character (LATIN SMALL LETTER E followed by COMBINING ACUTE ACCENT has the same visual representation as LATIN SMALL LETTER E WITH ACUTE). Users of SPARQL must take care to construct queries with IRIs that match the IRIs in the data. Further information about matching of similar characters can be found in Unicode Security Considerations [UNISEC] and Internationalized Resource Identifiers (IRIs) [RFC3987] Section 8.
The status of the parts of SPARQL 1.1 Protocol (this document) is as follows:
A conformant SPARQL Protocol service:
query
operation or the update
operation in the way described in this document ("SPARQL 1.1 Protocol");query
and update
operations;This specification extends and updates the SPARQL Protocol for RDF of January, 2008. The significant changes are: