Copyright © 2006-2007 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 uses WSDL 2.0 to describe a means for conveying SPARQL queries to an SPARQL query processing service and returning the query results to the entity that requested them. This protocol was developed by the W3C RDF Data Access Working Group (DAWG), 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 November 2007 publication is a Proposed Recommendation. W3C Members and other interested parties are invited to review the document through 10 December 2007.
This document is a product of the RDF Data Access Working Group and, in conjunction with the SPARQL Query Language for RDF and the SPARQL Query Results XML Format satisfies the requirements documented in RDF Data Access Use Cases and Requirements.
The first release of this document was 14 Jan 2005 and the RDF Data Access Working Group has made its best effort to address comments received since then, releasing several drafts and resolving a list of issues meanwhile. The group published a 25 January 2006 Last Call Working Draft, followed by a 6 Apr 2006 Candidate Recommendation. The change log summarizes changes since the publication of the Candidate Recommendation, and contains a log of changes since the Last Call draft.
The Working Group has satisfied the exit criteria set forth in the 6 April 2006 Candidate Recommendation as follows:
Aside from formal membership reviews, comments on this document should be sent to public-rdf-dawg-comments@w3.org, a mailing list with a public archive.
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.
SparqlQuery
Interface
query
Operationquery
In Messagequery
Out Messagequery
Fault MessagesSELECT
with service-supplied RDF datasetSELECT
with simple RDF datasetCONSTRUCT
with simple RDF dataset and HTTP content negotiationASK
with simple RDF datasetDESCRIBE
with simple RDF datasetSELECT
with complex RDF datasetSELECT
with query-only RDF datasetSELECT
with ambiguous RDF datasetSELECT
with malformed query faultSELECT
with query request refused faultSELECT
query using POST bindingSELECT
with internationalizationSELECT
with queryHttpPost binding and XML inputThis document (which refers to itself as "SPARQL Protocol for RDF") describes SPARQL Protocol, a means of conveying SPARQL queries from query clients to query processors. SPARQL Protocol has been designed for compatibility with the SPARQL Query Language for RDF [SPARQL]. SPARQL Protocol is described in two ways: first, as an abstract interface independent of any concrete realization, implementation, or binding to another protocol; second, as HTTP and SOAP bindings of this interface. This document, as well as the associated WSDL and W3C XML Schema documents, are primarily intended for software developers interested in implementing SPARQL query services and clients.
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].
When this document contains excerpts from other documents, including WSDL and XML Schema instances, it uses the following namespace prefixes and namespace URIs:
Prefix | Namespace URI |
---|---|
st |
http://www.w3.org/2005/09/sparql-protocol-types/# |
xs |
http://www.w3.org/2001/XMLSchema |
vbr |
http://www.w3.org/2005/sparql-results# |
rdf |
http://www.w3.org/1999/02/22-rdf-syntax-ns# |
whttp |
http://www.w3.org/2006/01/wsdl/http |
wsoap |
http://www.w3.org/2006/01/wsdl/soap |
soap |
http://www.w3.org/2003/05/soap-envelope |
wsdlx |
http://www.w3.org/2005/08/wsdl-extensions |
tns |
http://www.w3.org/2005/08/sparql-protocol-query/# |
This set of documents comprises the specification of the SPARQL Protocol:
SPARQL Protocol contains one interface, SparqlQuery
, which in turn contains one operation,
query
. SPARQL Protocol is described abstractly with WSDL 2.0 [WSDL2] in terms of a web service that implements its interface, types,
faults, and operations, as well as by HTTP and SOAP bindings. Note that while this document uses WSDL 2.0 to describe
SPARQL Protocol, there is no obligation on the part of any implementation to use any particular implementation strategy,
including the use of any WSDL library or programming language framework.
query
operationSparqlQuery
is the protocol's only interface. It
contains one operation, query
, which is used to
convey
a SPARQL
query string and, optionally,
an RDF
dataset description.
The query
operation is described as an
In-Out
message exchange pattern [WSDL-Adjuncts]. The constraints of
an In-Out message exchange pattern are as follows:
This pattern consists of exactly two messages, in order, as follows:
A message:
indicated by a Interface Message Reference component whose {message label} is "In" and {direction} is "in"
received from some node N
A message:
indicated by a Interface Message Reference component whose {message label} is "Out" and {direction} is "out"
sent to node N
This pattern uses the rule 2.2.1 Fault Replaces Message.
This interface and its operation are described in the following WSDL 2.0 fragment (from protocol-query.wsdl, which contains the relevant namespace declarations):
<!-- Abstract SparqlQuery Interface --> <interface name="SparqlQuery" styleDefault="http://www.w3.org/2006/01/wsdl/style/iri"> <!-- the Interface Faults --> <fault name="MalformedQuery" element="st:malformed-query"/> <fault name="QueryRequestRefused" element="st:query-request-refused"/> <!-- the Interface Operation --> <operation name="query" pattern="http://www.w3.org/2006/01/wsdl/in-out"> <documentation>The operation is used to convey queries and their results from clients to services and back again.</documentation> <input messageLabel="In" element="st:query-request"/> <output messageLabel="Out" element="st:query-result"/> <!-- the interface faults are out faults --> <outfault ref="tns:MalformedQuery" messageLabel="Out"/> <outfault ref="tns:QueryRequestRefused" messageLabel="Out"/> </operation> </interface>
query
In Message Abstractly, the contents of the In Message of SparqlQuery
's query
operation is an
instance of an XML Schema complex type, called st:query-request
in Excerpt 1.0, composed of two further
parts: one SPARQL query string; and zero or one RDF dataset descriptions. The SPARQL query string,
identified by one query
type, is defined by
[SPARQL] as "a sequence of characters in the language defined by the [SPARQL] grammar, starting with the Query
production". The RDF dataset description is composed of zero or one default RDF graphs — composed by the RDF
merge of the RDF graphs identified by zero or more default-graph-uri
types — and by zero or more
named RDF graphs, identified by zero or more named-graph-uri
types. These correspond to the
FROM
and FROM NAMED
keywords in [SPARQL], respectively.
These types are defined in the following XML Schema fragment, from protocol-types.xsd:
<xs:element name="query-request"> <xs:complexType> <xs:sequence> <xs:element minOccurs="1" maxOccurs="1" name="query" type="xs:string"> <xs:annotation> <xs:documentation>query is an xs:string constrained by the language definition, http://www.w3.org/TR/rdf-sparql-query/#grammar, as "a sequence of characters in the language defined by the [SPARQL] grammar, starting with the Query production".</xs:documentation> </xs:annotation> </xs:element> <xs:element minOccurs="0" maxOccurs="unbounded" name="default-graph-uri" type="xs:anyURI"/> <xs:element minOccurs="0" maxOccurs="unbounded" name="named-graph-uri" type="xs:anyURI"/> </xs:sequence> </xs:complexType> </xs:element>
Excerpt 1.1 XML Schema fragment
The RDF dataset may be specified either in a [SPARQL] query using FROM
and FROM NAMED
keywords; or it may be specified in the protocol described in this document; or it may be specified in both the query
string and in the protocol.
In the case where both the query and the protocol specify an RDF
dataset, but not the identical RDF dataset, the dataset
specified in the protocol
must be the RDF dataset consumed by
SparqlQuery
's query
operation.
A conformant SPARQL Protocol service may provide a
default RDF dataset against which SPARQL query requests are executed in cases where there is no RDF dataset specified in the
protocol or in the query request. A conformant SPARQL Protocol service
may refuse to process any query request that does not specify an RDF dataset. Finally, a conformant SPARQL Protocol service may refuse to process any
query request against any specified RDF dataset. See 2.1.4 query
Fault Messages, QueryRequestRefused
.
The BASE
keyword in the query 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". Section 5.1.2, "Base URI from the Encapsulating
Entity" defines how the Base IRI may come from an encapsulating
document, such as a SOAP envelope with an xml:base directive. 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 invocation
URI.
query
Out MessageAbstractly, the contents of the Out Message
of SparqlQuery
's query
operation is an
instance of an XML Schema complex type,
called query-result
in Excerpt 1.2, composed of either:
The query-result
type is defined in this W3C XML
Schema fragment, from protocol-types.xsd:
<xs:element name="query-result"> <xs:annotation> <xs:documentation>The type for serializing query results, either as XML or RDF/XML.</xs:documentation> </xs:annotation> <xs:complexType> <xs:choice> <xs:element maxOccurs="1" ref="vbr:sparql"/> <xs:element maxOccurs="1" ref="rdf:RDF"/> </xs:choice> </xs:complexType> </xs:element>
Excerpt 1.2 XML Schema fragment
query
Fault Messages[WSDL2-Adjuncts] defines several fault propagation rules which
specify how operation faults and messages
interact. The query
operation employs
the Fault
Replaces Message rule:
Any message after the first in the pattern may be replaced with a fault message, which must have identical direction. The fault message must be delivered to the same target node as the message it replaces, unless otherwise specified by an extension or binding extension. If there is no path to this node, the fault must be discarded.
Thus, the query
operation contained in the SparqlQuery
interface may return, in place of the Out Message, either the MalformedQuery
message or the
QueryRequestRefused
message, both of which are defined in this XML Schema fragment from protocol-types.xsd:
<xs:element type="xs:string" name="fault-details"> <xs:annotation> <xs:documentation> This element contains human-readable information about the fault returned by the SPARQL query processing service.</xs:documentation> </xs:annotation> </xs:element> <xs:element name="malformed-query"> <xs:complexType> <xs:all><xs:element minOccurs="0" maxOccurs="1" ref="st:fault-details"/></xs:all> </xs:complexType> </xs:element> <xs:element name="query-request-refused"> <xs:complexType> <xs:all><xs:element minOccurs="0" maxOccurs="1" ref="st:fault-details"/></xs:all> </xs:complexType> </xs:element>
When the value of the query
type is not a legal sequence of characters in the language defined by the
SPARQL grammar, the MalformedQuery
or QueryRequestRefused
fault message must be returned. According to the Fault Replaces Message Rule, if a WSDL fault is returned, including MalformedQuery
, an Out Message must not be returned.
When the MalformedQuery
fault message is returned, query processing services must
include explanatory, debugging, or other additional information for human consumption via the
fault-details
type defined in Excerpt 1.3.
This WSDL fault message should be returned when a client submits a request that the service refuses
to process. The QueryRequestRefused
fault message neither indicates whether the server may or may not
process a subsequent, identical request or requests, nor does it constrain a conformant SPARQL service from returning other HTTP status codes or HTTP
headers as appropriate given the semantics of [HTTP].
When the QueryRequestRefused
fault message is returned, query processing services must
include explanatory, debugging, or other additional information intended for human consumption via the
fault-details
type defined in Excerpt 1.3.
The SparqlQuery
interface operation query
described thus far is an abstract operation; it
requires protocol bindings to become an invocable operation. This next two sections of this document describe HTTP and SOAP
bindings. A conformant SPARQL Protocol service must
support the SparqlQuery
interface; if a SPARQL Protocol service supports HTTP bindings, it
must support the bindings as described in protocol-query.wsdl. A SPARQL Protocol service may support
other interfaces. See 2.3 SOAP Bindings for more information.
[WSDL2-Adjuncts] defines a means of binding abstract interface operations to HTTP. The HTTP bindings for the
query
operation (from protocol-query.wsdl) are as follows:
<!-- the HTTP GET binding for query operation --> <binding name="queryHttpGet" interface="tns:SparqlQuery" type="http://www.w3.org/2006/01/wsdl/http" whttp:version="1.1"> <fault ref="tns:MalformedQuery" whttp:code="400"/> <fault ref="tns:QueryRequestRefused" whttp:code="500"/> <operation ref="tns:query" wsdlx:safe="true" whttp:method="GET" whttp:faultSerialization="*/*" whttp:inputSerialization="application/x-www-form-urlencoded" whttp:outputSerialization="application/sparql-results+xml, application/rdf+xml, */*" /> </binding> <!-- the HTTP POST binding for query operation --> <binding name="queryHttpPost" interface="tns:SparqlQuery" type="http://www.w3.org/2006/01/wsdl/http" whttp:version="1.1"> <fault ref="tns:MalformedQuery" whttp:code="400"/> <fault ref="tns:QueryRequestRefused" whttp:code="500"/> <operation ref="tns:query" wsdlx:safe="true" whttp:method="POST" whttp:faultSerialization="*/*" whttp:inputSerialization="application/x-www-form-urlencoded, application/xml" whttp:outputSerialization="application/sparql-results+xml, application/rdf+xml, */*" /> </binding>
There are two HTTP bindings, queryHttpGet
and queryHttpPost
, both of which are
described as bindings of the SparqlQuery
interface. In each of these bindings, the two faults described in SparqlQuery interface, MalformedQuery
and QueryRequestRefused
, are bound
to HTTP status codes 400 Bad Request
and
500 Internal Server Error
, respectively [HTTP].
The queryHttpGet
binding should be used except in cases where the URL-encoded query exceeds
practical limits, in which case the queryHttpPost
binding should be used.
An Informative Note About Serialization Constraints. The output serialization of the
queryHttpGet
and queryHttpPost
bindings is intentionally under constrained in order to reflect the
variety of serialization types of RDF graphs. The fault serialization of queryHttpGet
and
queryHttpPost
is also intentionally under constrained. A conformant SPARQL Protocol service can provide alternative WSDL interfaces
and bindings with different constraints.
This binding of the query
operation uses [HTTP] GET
with the following serialization type
constraints: the value of whttp:faultSerialization
is */*
; second, the value of
whttp:inputSerialization
is application/x-www-form-urlencoded
with UTF-8 encoding; and,
third, the whttp:outputSerialization
is application/sparql-results+xml
with UTF-8 encoding,
application/rdf+xml
with UTF-8 encoding, and */*
.
This binding of the query
operation uses [HTTP] POST
with the following serialization type
constraints: the value of whttp:faultSerialization
is */*
; second, the value of
whttp:inputSerialization
is application/x-www-form-urlencoded
with UTF-8 encoding and
application/xml
with UTF-8 encoding; and, third, the whttp:outputSerialization
is
application/sparql-results+xml
with UTF-8 encoding, application/rdf+xml
with UTF-8 encoding, and
*/*
.
The following abstract HTTP trace examples illustrate invocation of
the query
operation under several different
scenarios. These example traces are abstracted from complete HTTP
traces in three ways: (1) In each example the string
"EncodedQuery" represents the URL-encoded string equivalent of
the SPARQL query given in the first block of each example; (2) only
partial response bodies, containing the query results, are displayed;
(3) the URI values of default-graph-uri
and named-graph-uri
are also not URL-encoded.
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.example/sparql/, as illustrated in this HTTP trace:
GET /sparql/?query=EncodedQuery 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 distinct="false" ordered="false">
<result>
<binding name="book"><uri>http://www.example/book/book5</uri></binding>
<binding name="who"><bnode>r29392923r2922</bnode></binding>
</result>
...
<result>
<binding name="book"><uri>http://www.example/book/book6</uri></binding>
<binding name="who"><bnode>r8484882r49593</bnode></binding>
</result>
</results>
</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=EncodedQuery&default-graph-uri=http://www.other.example/books 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>
...
<results distinct="false" ordered="false">
<result>
<binding name="book"><uri>http://www.example/book/book2</uri></binding>
<binding name="who"><bnode>r1115396427r1133</bnode></binding>
</result>
<result>
<binding name="book"><uri>http://www.example/book/book3</uri></binding>
<binding name="who"><bnode>r1115396427r1133</bnode></binding>
</result>
<result>
<binding name="book"><uri>http://www.example/book/book1</uri></binding>
<binding name="who"><literal>J.K. Rowling</literal></binding>
</result>
</results>
</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://www.example/jose-foaf.rdf HTTP/1.1 Host: www.example User-agent: sparql-client/0.1 Accept: text/rdf+n3, 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/rdf+n3
@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";
...
foaf:schoolHomepage <http://www.edu.example/>;
foaf:workplaceHomepage <http://www.corp.example/>;
foaf:homepage <http://www.example/jose/>;
foaf:knows myfoaf:juan;
rdf:type foaf:Person.
myfoaf:juan foaf:mbox <mailto:juan@mail.example>;
rdf:type foaf:Person.
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://www.example/books 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://www.example/books 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://www.example/publishers &default-graph-uri=http://www.example/morepublishers&named-graph-uri=http://your.example/foaf-alice &named-graph-uri=http://www.example/foaf-bob&named-graph-uri=http://www.example/foaf-susan &named-graph-uri=http://this.example/john/foaf 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>
...
<results ordered="false" distinct="false">
<result>
<binding name="who">
<literal>Alice</literal>
</binding>
<binding name="g">
<uri>http://your.example/foaf-alice</uri>
</binding>
<binding name="mbox">
<uri>mailto:alice@example.org</uri>
</binding>
</result>
<result>
<binding name="who">
<literal>Bob</literal>
</binding>
<binding name="g">
<uri>http://www.example/foaf-bob</uri>
</binding>
<binding name="mbox">
<uri>mailto:bob@work.example</uri>
</binding>
</result>
<result>
<binding name="who">
<literal>Susan</literal>
</binding>
<binding name="g">
<uri>http://www.example/foaf-susan</uri>
</binding>
<binding name="mbox">
<uri>mailto:susan@work.example</uri>
</binding>
</result>
<result>
<binding name="who">
<literal>John</literal>
</binding>
<binding name="g">
<uri>http://this.example/john/foaf</uri>
</binding>
<binding name="mbox">
<uri>mailto:john@home.example</uri>
</binding>
</result>
</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/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#">
...
<head>
<variable name="who"/>
<variable name="g"/>
<variable name="mbox"/>
</head>
<results ordered="false" distinct="false">
<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 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://www.example/morepublishers &named-graph-uri=http://www.example/bob&named-graph-uri=http://www.example/alice 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 ordered="false" distinct="false"> <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://www.example/morepublishers HTTP/1.1 Host: www.example User-agent: sparql-client/0.1
With the response — the MalformedQuery
fault
replacing the Out Message, as per 2.1
SparqlQuery — 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://another.example/protein-db.rdf HTTP/1.1 Host: www.example User-agent: sparql-client/0.1
With the response — the QueryRequestRefused
fault replacing the Out Message, as per 2.1
SparqlQuery — 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/html; charset=UTF-8 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>SPARQL Processing Service: Query Request Refused</title> </head> <body> <p> Query Request Refused: your request could not be processed because <code>http://another.example/protein-db.rdf</code> could not be retrieved within the time alloted.</p> </body> </html>
Some SPARQL queries, perhaps machine generated, may be longer than can be reliably conveyed by way of the HTTP GET binding described in 2.2 HTTP Bindings. In those cases the POST binding described in 2.2 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 XML: <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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML:date; :dtstamp "2002-09-06T03:12:53Z"^^XML:dateTime; :dtstart "2002-11-03"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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"^^XML: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://another.example/calendar.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 ordered="false" distinct="false">
<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. Miami @ Arrowhead Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>BYE</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. San Francisco @ 49ers Stadium at Candlestick Point</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. Buffalo @ Arrowhead Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. NY Jets @ Giants Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. San Diego @ Qualcomm Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. Denver @ Arrowhead Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. Oakland @ Arrowhead Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. Seattle @ Seahawks Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. Arizona @ Arrowhead Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. St. Louis @ Arrowhead Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. Denver @ INVESCO Field at Mile High</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. San Diego @ Arrowhead Stadium</literal>
</binding>
</result>
<result>
<binding name="summary">
<literal>Chiefs vs. Oakland @ Network Associates Coliseum</literal>
</binding>
</result>
</results>
</sparql>
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=EncodedQuery 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>
In some future version SPARQL queries could be serialized as XML and conveyed to
a SPARQL query service by way of HTTP POST
. This SPARQL query
<?xml version="1.0"?> <rdf-query xmlns="http://example.org/SparqlX/"> <select><variable name="book"/><variable name="who"/></select> <query-pattern> <triple-pattern> <subject><variable name="book"/></subject> <predicate><uri>http://purl.org/dc/elements/1.1/creator</uri></predicate> <object><variable name="who"/></object> </triple-pattern> </query-pattern> </rdf-query>
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: my-sparql-client/0.1 Content-type: application/xml <?xml version="1.0"?> <rdf-query xmlns="http://example.org/SparqlX/"> <select><variable name="book"/><variable name="who"/></select> <query-pattern> <triple-pattern> <subject><variable name="book"/></subject> <predicate><uri>http://purl.org/dc/elements/1.1/creator</uri></predicate> <object><variable name="who"/></object> </triple-pattern> </query-pattern> </rdf-query>
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 distinct="false" ordered="false">
<result>
<binding name="book"><uri>http://www.example/book/book5</uri></binding>
<binding name="who"><bnode>r29392923r2922</bnode></binding>
</result>
...
<result>
<binding name="book"><uri>http://www.example/book/book6</uri></binding>
<binding name="who"><bnode>r8484882r49593</bnode></binding>
</result>
</results>
</sparql>
[WSDL2-Adjuncts] defines a means of binding abstract interface
operations to SOAP. The SOAP bindings for the query
operation
(from protocol-query.wsdl)
are as follows:
<binding name="querySoap" interface="SparqlQuery" type="http://www.w3.org/2006/01/wsdl/soap" wsoap:version="1.2" wsoap:protocol="http://www.w3.org/2003/05/soap/bindings/HTTP"> <fault ref="tns:MalformedQuery" wsoap:code="soap:Sender" /> <fault ref="tns:QueryRequestRefused" wsoap:code="soap:Sender" /> <operation ref="tns:query" wsoap:mep="http://www.w3.org/2003/05/soap/mep/request-response" /> </binding>
The name of the SOAP binding
of SparqlQuery
's query
operation
is querySoap
; it is a SOAP binding because of the value
of type
attribute, which is set to the URI identifying
SOAP. The version of SOAP is 1.2
. The underlying
protocol used in this SOAP binding is HTTP, as determined by the URI
value of the wsoap:protocol
attribute. If a SPARQL
Protocol service supports SOAP bindings with the value of
the {http://www.w3.org/2006/01/wsdl/soap, protocol}
attribute set
to http://www.w3.org/2003/05/soap/bindings/HTTP
,
it must support the bindings as described
in protocol-query.wsdl. SOAP
bindings with wsoap:protocol
values set to transmission
protocols other than HTTP are not described in this document.
The two fault
elements refer to the fault messages
defined in the SparqlQuery
interface.
Finally, the operation
element references
the query
operation of the SparqlQuery
interface which has been previously described
in Excerpt 1.0 above. Since this SOAP
binding describes the operation as using HTTP as the underlying
transport protocol, the value of the wsoap:mep
attribute determines which HTTP method is to be used. This operation
is described as being implemented by a SOAP message exchange
pattern http://www.w3.org/2003/05/soap/mep/request-response
,
which, according to [SOAP12] 7.4 Supported Features, is bound to an
HTTP POST
method.
POST /services/sparql-query HTTP/1.1 Content-Type: application/soap+xml Accept: application/soap+xml, multipart/related, text/* User-Agent: Axis/1.2.1 Host: www.example SOAPAction: "" Content-Length: 438 <?xml version="1.0" encoding="UTF-8"?> <soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <soapenv:Body> <query-request xmlns="http://www.w3.org/2005/09/sparql-protocol-types/#"> <query>SELECT ?z {?x ?y ?z . FILTER regex(?z, 'Harry')}</query> </query-request> </soapenv:Body> </soapenv:Envelope>
HTTP/1.1 200 OK
Content-Type: application/soap+xml
<?xml version="1.0" encoding="utf-8"?>
<soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<soapenv:Body>
<query-result xmlns="http://www.w3.org/2005/09/sparql-protocol-types/#">
<ns1:sparql xmlns:ns1="http://www.w3.org/2005/sparql-results#">
<ns1:head>
<ns1:variable name="z"/>
</ns1:head>
<ns1:results distinct="false" ordered="false">
<ns1:result>
<ns1:binding name="z">
<ns1:literal>Harry Potter and the Chamber of Secrets</ns1:literal>
</ns1:binding>
</ns1:result>
...
<ns1:result>
<ns1:binding name="z">
<ns1:literal>Harry Potter and the Half-Blood Prince</ns1:literal>
</ns1:binding>
</ns1:result>
<ns1:result>
<ns1:binding name="z">
<ns1:literal>Harry Potter and the Goblet of Fire</ns1:literal>
</ns1:binding>
</ns1:result>
<ns1:result>
<ns1:binding name="z">
<ns1:literal>Harry Potter and the Philosopher's Stone</ns1:literal>
</ns1:binding>
</ns1:result>
<ns1:result>
<ns1:binding name="z">
<ns1:literal>Harry Potter and the Order of the Phoenix</ns1:literal>
</ns1:binding>
</ns1:result>
<ns1:result>
<ns1:binding name="z">
<ns1:literal>Harry Potter and the Prisoner Of Azkaban</ns1:literal>
</ns1:binding>
</ns1:result>
</ns1:results>
</ns1:sparql>
</query-result>
</soapenv:Body>
</soapenv:Envelope>
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.
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 Protocol for RDF (this document) is as follows:
Further, both protocol-query.wsdl and protocol-types.xsd are normative.
A conformant SPARQL Protocol service:
SparqlQuery
interface;query
operation of the SparqlQuery
interface;query
in the way described in this document ("SPARQL Protocol for RDF"), in protocol-query.wsdl, and protocol-types.xsd;query
operation other than the normative HTTP or SOAP bindings described by SPARQL Protocol for RDF; andMy thanks to members of DAWG, especially Bijan Parsia, Bryan Thompson, Andy Seaborne, Steve Harris, Eric Prud'hommeaux, Yoshio FUKUSHIGE, Howard Katz, Dirk-Willem van Gulik, Dan Connolly, and Lee Feigenbaum. Particular thanks are owed to Elias Torres for his generous assistance and support. Thanks as well to my UMD colleagues Jim Hendler, Ron Alford, Amy Alford, Yarden Katz, Chris Testa, and members of the Mindlab Semantic Web Undergraduate Social. Particular thanks are also owed my NASA colleague and friend, Andy Schain. I also thank Jacek Kopecky, Morten Frederiksen, Mark Baker, Jan Algermissen, Danny Ayers, Bernd Simon, Graham Klyne, Arjohn Kampman, Tim Berners-Lee, Dan Brickley, Patrick Stickler, Karl Dubost, Jonathan Marsh, Leigh Dodds, David Wood, Reto Krummenacher, Thomas Roessler, Danny Weitzner, Paul Downey, Hugo Haas, Richard Newman.
A brief, high-level summary of changes to this specification and related materials since the 6 Apr 2006 Candidate Recommendation publication:
Detailed CVS change history since 6 Apr 2006 Candidate Recommendation follows:
$Log: Overview.html,v $ Revision 1.5 2018/10/09 13:16:47 denis fix validation of xhtml documents Revision 1.4 2017/10/02 10:33:27 denis add fixup.js to old specs Revision 1.3 2007/11/12 08:31:59 eric ~ update to 2006/01/wsdl/ namespaces Revision 1.2 2007/11/12 08:15:34 eric ~ well-formedness fix Revision 1.1 2007/11/12 08:11:33 eric created Revision 1.126 2007/11/12 06:05:50 eric ~ link typo Revision 1.125 2007/10/24 14:22:37 lfeigenb update links to WSDL and XSD to point to /2007/SPARQL/xxx Revision 1.124 2007/10/24 04:01:40 eric validate Revision 1.123 2007/10/24 03:52:34 eric well-formed Revision 1.122 2007/10/23 14:52:39 lfeigenb updated editor emails and affiliations Revision 1.121 2007/10/16 16:57:17 lfeigenb added high level change summary to change log Revision 1.120 2007/02/20 06:53:13 etorres added base-iri sub-section to 2.1.2 as per 20070213 dawg meeting. added normative reference to rfc3986 added two new editors to document Revision 1.119 2006/05/16 15:28:55 kclark removed large, unneeded html comment added soap namespace binding to table Changes from Last Call to Candidate Recommendation: Revision 1.118 2006/03/29 12:53:20 connolly cite 27 Mar CR version of WSDL2, WSDL2-Adjuncts using bib generator Revision 1.117 2006/03/27 20:55:57 kclark updated WSDL pointers, again Revision 1.116 2006/03/24 19:56:15 kclark changed long query to something that's testable added results for long query Revision 1.115 2006/03/24 18:24:01 kclark updated WSDL 2.0 links updated description of In-Out MEP updated definition of Fault Replaces Message rule fixed a bug where I refer to an XML Schema excerpt as a WSDL excerpt synched excerpts of the WSDL with the WSDL (the namespace fixes from 1.18/19 of sparql-protocol-query.wsdl; and the wsdlx:safety="true" fixes too) changed "practicable" to "practical" removed the word "respectively" added actual long query for post example put todo span marker around the results for the long query and the kanji example -- these are still TODO made a link to the sparqlx.rnc in an informative HTTP example (all the HTTP examples are informative) Revision 1.114 2006/03/20 21:58:41 kclark fix buggy typo Revision 1.113 2006/03/20 21:57:10 kclark changed should to must return fault on bad query string fixed soap xml malformedness Revision 1.112 2006/02/08 14:21:03 kclark fixing broken 'since' language Revision 1.111 2006/02/08 13:55:27 kclark tweaked changelog Changes prior to Last Call: tweaked language about malformed query and out messages tweaked language about malformedquery wsdl fault propagation added charset to text/plain in 2.2.1.9 added charset to text/html in 2.2.1.10 added a doctype declaration in 2.2.1.10 removed application/dime from the SOAP example replacing text/xml with application/soap+xml removed 3.2 privacy section (no consensus from experts on what this section should do; seems out of scope now) changed SHOULD to MAY in re: logging requests added "Rejecting Query Requests to RDF Datasets" section with 3 "may" clauses added a conformance section (4. Conformance) (per Q&A review) conformance section includes statement of which parts of the doc are normative or informative added a bit about who might be interested in this spec (per Q&A review) synched language with WSDL changes (mostly this involves changes to the HTTP bindings section) tightened the distinction between SPARQL Protocol (the wsdl, xsd, and for-humans spec) and SPARQL Protocol for RDF (the for-humans spec) changed the language of QueryRequestRefused: must is now should and there's an explicit statement that HTTP status codes and headers can be returned irrespective of the two WSDL faults defined by SPARQL Protocol changed fault-details should be returned to must be returned to help distinguish in the 400 and 500 cases between HTTP status codes and WSDL faults added an informative note about serialization constraints added 2.2.1.12 SELECT with internationalization (incomplete) added 2.2.1.13 SELECT with queryHttpPost between and XML input changed old SOAP namespace in the SOAP example removed charset utf-8 bits simplified the language describing QueryRequestRefused no obligation to use WSDL language added erroneous query-result types changed to correct query-request types corrected SOAP namespace in the SOAP example (now using the SOAP 1.2 namespace instead of the SOAP 1.1 NS) added a table of local name to NS URI bindings for legibility added a list of the documents comprising the protocol, with links, for legibility corrected IMT in the DESCRIBE example (from app/sparql-results+xml to app/rdf+xml)