org.lacibus.triplestore

Class Triple

java.lang.Object

org.lacibus.triplestore.Triple

All Implemented Interfaces:

java.lang.Comparable<Triple>

public abstract class Triple
extends java.lang.Object
implements java.lang.Comparable<Triple>

A triple consists of a subject that is an item, a verb that is also an item, and an object that is a Datum. A Datum may be an item or a data value that is a boolean, an integer, a real number, a piece of text, or a sequence of bytes.

A triple is held in the same source as its subject, and has its own numeric identifier in that source.

Access to a triple is determined by the access levels of its subject, its verb, and its object if that is an item.

Objects that are pieces of text or sequences of bytes can be of arbitrary size. Non-item triples contain summaries of their objects, rather than the objects themselves. Searches in the triple store first find triples with objects whose summaries match the criteria. These objects are then retrieved from the sources to determine whether they match. Objects whose summaries do not meet the criteria are not retrieved.

For triples with objects that are booleans, integers, or real numbers, the value of the object can be determined from its summary. For triples with objects that are items, the object is stored in the triple. It is only text and binary objects that need to be retrieved from the sources.

Method Summary

Modifier and Type	Method and Description
int	compareTo(Triple t)
boolean	equals(java.lang.Object o)
Id	getId() Get the triple's identifier
Datum	getObject(StoreSession session) Get the triple's object
abstract long	getObjectSummaryValue() Get the object's summary value.
Datum.Type	getObjectType() Get the triple's object type
abstract long	getSourceNr() Get the numeric identifier of triple's source
Item	getSubject() Get the triple's subject
Id	getSubjectId() Get the triple's subject identifier
long	getTripleNr() Get the numeric identifier of the triple in its source
Item	getVerb() Get the triple's verb
Id	getVerbId() Get the triple's verb identifier

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getSourceNr

public abstract long getSourceNr()

Get the numeric identifier of triple's source

Returns:

the numeric identifier of the triple's source

getTripleNr

public long getTripleNr()

Get the numeric identifier of the triple in its source

Returns:

the numeric identifier of the triple in its source

getId

public Id getId()

Get the triple's identifier

Returns:

the triple's identifier

getSubjectId

public Id getSubjectId()

Get the triple's subject identifier

Returns:

the triple's subject identifier

getSubject

public Item getSubject()

Get the triple's subject

Returns:

the triple's subject

getVerbId

public Id getVerbId()

Get the triple's verb identifier

Returns:

the triple's verb identifier

getVerb

public Item getVerb()

Get the triple's verb

Returns:

the triple's verb

getObjectType

public Datum.Type getObjectType()

Get the triple's object type

Returns:

the triple's object type

getObjectSummaryValue

public abstract long getObjectSummaryValue()

Get the object's summary value.

Returns:

the triple object's summary value

getObject

public Datum getObject(StoreSession session)
                throws TripleStoreNonFatalException,
                       TripleStoreFatalException,
                       SourceConnectorException,
                       NotInOperationException

Get the triple's object

Parameters:

session - the session requesting the operation. It must have read access to the subject and verb, and to the object if this is an item.

Returns:

the triple's object, or null if it cannot be returned

Throws:

TripleStoreNonFatalException

TripleStoreFatalException

SourceConnectorException

NotInOperationException

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

compareTo

public int compareTo(Triple t)

Specified by:

compareTo in interface java.lang.Comparable<Triple>