com.bigdata.rdf.store

Interface BD

public interface BD

A vocabulary for bigdata specific extensions.

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
static org.openrdf.model.URI	ALP_SERVICE The well-known URI of the ALP SERVICE extension.
static org.openrdf.model.URI	DESCRIBE The URI for the "DESCRIBE" service.
static String	NAMESPACE The namespace used for bigdata specific extensions.
static org.openrdf.model.URI	NULL_GRAPH Sesame has the notion of a "null" graph.
static org.openrdf.model.URI	SERVICE_PARAM URI that can be used as the Subject of magic triple patterns for bigdata SERVICEs.
static org.openrdf.model.URI	SID The name of a per-statement attribute whose value is recognized in RDF/XML as the statement identifier for statement described by the element on which it appears.
static org.openrdf.model.URI	STATEMENT_TYPE The name of a per-statement attribute whose indicates whether the statement is an axiom, inference, or explicit in the knowledge base.
static org.openrdf.model.URI	VIRTUAL_GRAPH A predicate used to model the membership of a virtual graph.

Field Detail

NAMESPACE

static final String NAMESPACE

The namespace used for bigdata specific extensions.

See Also:

Constant Field Values

SID

static final org.openrdf.model.URI SID

The name of a per-statement attribute whose value is recognized in RDF/XML as the statement identifier for statement described by the element on which it appears. The bigdata:sid attribute is allowed on elements describing RDF statements and serves as a per-statement identifier. The value of the bigdata:sid attribute must conform to the syntactic constraints of a blank node. By re-using the value of the bigdata:sid attribute within other statements in the same RDF/XML document, the client can express statements about the statements.

This RDF/XML extension allows us to inline provenance (statements about statements) with RDF/XML to clients in a manner which has minor impact on unaware clients (they will perceive additional statements whose predicate is bigdata:sid). In addition, clients aware of this extension can submit RDF/XML with inline provenance.

For example:

 <rdf:Description rdf:about="http://www.foo.org/A">
     <label bigdata:sid="_S67" xmlns="http://www.w3.org/2000/01/rdf-schema#">abc</label>
 </rdf:Description>
 

STATEMENT_TYPE

static final org.openrdf.model.URI STATEMENT_TYPE

The name of a per-statement attribute whose indicates whether the statement is an axiom, inference, or explicit in the knowledge base. This attribute is strictly informative for clients and is ignored when loading data into a knowledge base.

The value will be one of

Axiom

The statement is an axiom that has not been explicitly asserted.

Inferred

The statement is an inference that has not been explicitly asserted.

Explicit

The statement has been explicitly asserted.

Note: If the knowledge base supports truth maintenance and an explicit statement is deleted from the knowledge base but it remains provable as an inference or an axiom then then knowledge base will continue to report it as either an axiom or an inference as appropriate.

DESCRIBE

static final org.openrdf.model.URI DESCRIBE

The URI for the "DESCRIBE" service.

See Also:

DescribeServiceFactory, Describe Cache

NULL_GRAPH

static final org.openrdf.model.URI NULL_GRAPH

Sesame has the notion of a "null" graph. Any time you insert a statement into a quad store and the context position is not specified, it is actually inserted into this "null" graph. If SPARQL DATASET is not specified, then all contexts are queried and you will see statements from the "null" graph as well as from any other context. com.bigdata.rdf.sail.BigdataSailConnection#getStatements(Resource, URI, Value, boolean, Resource...) will return statements from the "null" graph if the context is either unbound or is an array whose sole element is null.

Given

 void foo(Resource s, final URI p, final Value o, final Resource... contexts)
 

foo(s,p,o)

All named graphs are addressed. The contexts parameter will be a Resource[0] reference.

foo(s,p,o,(Resource[]) null)

Note: openrdf does not allow this invocation pattern - the Resource[] MUST NOT be a null reference.

foo(s,p,o,(Resource) null)

The openrdf "nullGraph" is addressed. The contexts parameter will be Resource[]{null}. Java will autobox the Resource reference as a Resource[]{null} array.

foo(s,p,o,x,y,z)

The openrdf named graphs (x,y,z) are addressed. The contexts parameter will be Resource[]{x,y,z}.

foo(s,p,o,x,null,z)

The openrdf named graphs (x,nullGraph,z) are addressed. The contexts parameter will be Resource[]{x,null,z}

See Also:

Resource... contexts not encoded/decoded according to openrdf semantics (REST API) , com.bigdata.rdf.sail.BigdataSailConnection#addStatement(Resource, URI, Value, Resource...), com.bigdata.rdf.sail.BigdataSailConnection#getStatements(Resource, URI, Value, boolean, Resource...), SESAME.NIL

VIRTUAL_GRAPH

static final org.openrdf.model.URI VIRTUAL_GRAPH

A predicate used to model the membership of a virtual graph. The following assertions declare the membership of a virtual graph as the graphs (:g1,:g2).

 :vg bd:virtualGraph :g1
 :vg bd:virtualGraph :g2
 

Virtual graphs are addressed through a SPARQL syntax extension:

 FROM VIRTUAL GRAPH
 FROM NAMED VIRTUAL GRAPH
 

If :vg as declared above is addressed using FROM VIRTUAL GRAPH then its member graphs (:g1,:g2) are added to the default graph for the query.

If :vg as declared above is addressed using FROM NAMED VIRTUAL GRAPH then its member graphs (:g1,:g2) are added to the named graphs for the query.

See Also:

Virtual Graphs (ticket), Virtual Graphs (wiki)

SERVICE_PARAM

static final org.openrdf.model.URI SERVICE_PARAM

URI that can be used as the Subject of magic triple patterns for bigdata SERVICEs. There may be zero or more such triple patterns. The Predicate (key) and Object (val) positions for those triple patterns are extracted into a ServiceParams object. For each key, there may be one or more values.

 SERVICE  {
   bd:serviceParam :key1 :val1 .
   bd:serviceParam :key1 :val2 .
   bd:serviceParam :key2 :val3 .
 }
 

See Also:

ServiceParams.

ALP_SERVICE

static final org.openrdf.model.URI ALP_SERVICE

The well-known URI of the ALP SERVICE extension.

See Also:

ASTALPServiceOptimizer, Configurable ALP Service , Document the ALP Service