org.universAAL.context.che.database.impl
Class SesameBackend

java.lang.Object
  org.universAAL.context.che.database.impl.SesameBackend

All Implemented Interfaces:

Backend

Direct Known Subclasses:

SesameBackendCrd, SesameBackendCrdClc, SesameBackendCrdClc2, SesameBackendWithConfidence

public class SesameBackend
extends Object
implements Backend

Implementation of Backend that uses Sesame to store and retrieve the context events in/from an underlying store server (a SAIL in Sesame). In this case it uses the Sesame native Filesystem repository, interfaced with a forward chaining RDFS inferencer.

Author:

Alvaro Fides Valero

Field Summary

protected MessageContentSerializer

uAALParser uaal-turtle parser.

Constructor Summary

SesameBackend()

Method Summary

void	close() Closes the connection to the store.
void	connect() Establishes the connection to the store.
void	populate() Fills the initial store with the OWL data of the ontologies from the OWL files in the config folder (or registered in the system).
String	queryBySPARQL(String input) Returns the result of a SPARQL query issued to the underlying store.
void	removeOldEvents(long tst) Removes all events from the underlying store that were received until the specified timestamp.
ArrayList	retrieveEvent(String subject, String subjecttype, String predicate, Object object, Integer confidence, Long expiration, Object provider, Long tstamp) Retrieves a list of ContextEvent from the underlying store, which members are the context events that match the parameters passed.
ArrayList	retrieveEventsBetweenTstmp(String subject, String subjecttype, String predicate, Object object, Integer confidence, Long expiration, ContextProvider provider, Long tstamp, Long tstfrom, Long tstto) Retrieves a list of ContextEvent from the underlying store, which members are the context events that match the parameters passed, and were received within the specified time range.
ArrayList	retrieveEventsBySPARQL(String input) Retrieves a list of ContextEvent from the underlying store, as a result of a SPARQL query.
ArrayList	retrieveEventsFromTstmp(String subject, String subjecttype, String predicate, Object object, Integer confidence, Long expiration, ContextProvider provider, Long tstamp, Long tstfrom) Retrieves a list of ContextEvent from the underlying store, which members are the context events that match the parameters passed, and were received after the specified timestamp.
ArrayList	retrieveEventsToTstmp(String subject, String subjecttype, String predicate, Object object, Integer confidence, Long expiration, ContextProvider provider, Long tstamp, Long tstto) Retrieves a list of ContextEvent from the underlying store, which members are the context events that match the parameters passed, and were received before the specified timestamp.
void	setuAALParser(MessageContentSerializer service) Set the MessageContentSerializer universAAL Parser that can be used to serialize and parse RDF data to universAAL data and vice-versa.
void	storeEvent(ContextEvent e) Stores a ContextEvent in the underlying store.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

uAALParser

protected MessageContentSerializer uAALParser

uaal-turtle parser.

Constructor Detail

SesameBackend

public SesameBackend()

Method Detail

connect

public void connect()

Description copied from interface: Backend

Establishes the connection to the store.

Specified by:

connect in interface Backend

populate

public void populate()
              throws org.openrdf.repository.RepositoryException,
                     org.openrdf.rio.RDFParseException,
                     IOException

Description copied from interface: Backend

Fills the initial store with the OWL data of the ontologies from the OWL files in the config folder (or registered in the system). Also used for updates when new ontologies are installed.

Specified by:

populate in interface Backend

Throws:

org.openrdf.repository.RepositoryException

org.openrdf.rio.RDFParseException

IOException

close

public void close()

Description copied from interface: Backend

Closes the connection to the store.

Specified by:

close in interface Backend

storeEvent

public void storeEvent(ContextEvent e)

Description copied from interface: Backend

Stores a ContextEvent in the underlying store.

Specified by:

storeEvent in interface Backend

Parameters:

e - The context event to be stored.

queryBySPARQL

public String queryBySPARQL(String input)

Description copied from interface: Backend

Returns the result of a SPARQL query issued to the underlying store. The types of SPARQL queries allowed depend on the underlying implementation, but these are mandated to include at least SELECT and DESCRIBE, and encouraged to also allow CONSTRUCT and ASK. SPARQL-Update is optional. Implementations should inform in case an unsupported query is received. The underlying implementations should return results in RDF/XML-ABBREV format encoded in UTF-8 in case of RDF models, and also if possible in case of lists of bindings for SELECT queries. Results for ASK and UPDATE queries (if implemented) should follow the format \"true\" or \"false\" Strings in case of ASK and \"true\" in case of a successful UPDATE query.

Specified by:

queryBySPARQL in interface Backend

Parameters:

input - The SPARQL query to be executed.

Returns:

The serialized form of the result from the execution of the query.

retrieveEventsBySPARQL

public ArrayList retrieveEventsBySPARQL(String input)

Description copied from interface: Backend

Retrieves a list of ContextEvent from the underlying store, as a result of a SPARQL query.

Specified by:

retrieveEventsBySPARQL in interface Backend

Parameters:

input - The SPARQL query that defines the events to be returned. The variable that represents the event MUST be named c. For instance: "SELECT ?c WHERE {...". Only SELECT queries are allowed.

Returns:

The list of context events that matched the query.

retrieveEvent

public ArrayList retrieveEvent(String subject,
                               String subjecttype,
                               String predicate,
                               Object object,
                               Integer confidence,
                               Long expiration,
                               Object provider,
                               Long tstamp)

Description copied from interface: Backend

Retrieves a list of ContextEvent from the underlying store, which members are the context events that match the parameters passed. A parameter can be passed a value of null for wildcarding.

This is not used in the current version. Will probably be deprecated.

Specified by:

retrieveEvent in interface Backend

Parameters:

subject - The URI of the subject of the event to be matched

subjecttype - The URI of the type of subject of the event to be matched

predicate - The URI of the predicate of the event to be matched

object - The Object of the event to be matched. It depends on the implementer of this method how to match the object.

confidence - The confidence of the event to be matched

expiration - The expiration time of the event to be matched

provider - The context provider of the event to be matched

tstamp - The timestamp in milliseconds of the event to be matched

Returns:

The list of context events that matched the values passed as parameters.

retrieveEventsBetweenTstmp

public ArrayList retrieveEventsBetweenTstmp(String subject,
                                            String subjecttype,
                                            String predicate,
                                            Object object,
                                            Integer confidence,
                                            Long expiration,
                                            ContextProvider provider,
                                            Long tstamp,
                                            Long tstfrom,
                                            Long tstto)

Description copied from interface: Backend

Retrieves a list of ContextEvent from the underlying store, which members are the context events that match the parameters passed, and were received within the specified time range. A parameter can be passed a value of null for wildcarding.

Specified by:

retrieveEventsBetweenTstmp in interface Backend

Parameters:

subject - The URI of the subject of the event to be matched

subjecttype - The URI of the type of subject of the event to be matched

predicate - The URI of the predicate of the event to be matched

object - The Object of the event to be matched. It depends on the implementer of this method how to match the object.

confidence - The confidence of the event to be matched

expiration - The expiration time of the event to be matched

provider - The context provider of the event to be matched

tstamp - The timestamp in milliseconds of the event to be matched. If not null, only events with this specified timestamp will be returned, as long as it is inside the time range

tstfrom - The timestamp in milliseconds from which events are requested. Only events stored after this timestamp will be returned.

tstto - The timestamp in milliseconds until which events are requested. Only events stored before this timestamp will be returned.

Returns:

The list of context events that matched the values passed as parameters.

retrieveEventsFromTstmp

public ArrayList retrieveEventsFromTstmp(String subject,
                                         String subjecttype,
                                         String predicate,
                                         Object object,
                                         Integer confidence,
                                         Long expiration,
                                         ContextProvider provider,
                                         Long tstamp,
                                         Long tstfrom)

Description copied from interface: Backend

Retrieves a list of ContextEvent from the underlying store, which members are the context events that match the parameters passed, and were received after the specified timestamp. A parameter can be passed a value of null for wildcarding.

Specified by:

retrieveEventsFromTstmp in interface Backend

Parameters:

subject - The URI of the subject of the event to be matched

subjecttype - The URI of the type of subject of the event to be matched

predicate - The URI of the predicate of the event to be matched

object - The Object of the event to be matched. It depends on the implementer of this method how to match the object.

confidence - The confidence of the event to be matched

expiration - The expiration time of the event to be matched

provider - The context provider of the event to be matched

tstamp - The timestamp in milliseconds of the event to be matched. If not null, only events with this specified timestamp will be returned, as long as it is inside the time range specified by tstinputfrom

tstfrom - The timestamp in milliseconds from which events are requested. Only events stored after this timestamp will be returned.

Returns:

The list of context events that matched the values passed as parameters.

retrieveEventsToTstmp

public ArrayList retrieveEventsToTstmp(String subject,
                                       String subjecttype,
                                       String predicate,
                                       Object object,
                                       Integer confidence,
                                       Long expiration,
                                       ContextProvider provider,
                                       Long tstamp,
                                       Long tstto)

Description copied from interface: Backend

Retrieves a list of ContextEvent from the underlying store, which members are the context events that match the parameters passed, and were received before the specified timestamp. A parameter can be passed a value of null for wildcarding.

Specified by:

retrieveEventsToTstmp in interface Backend

Parameters:

subject - The URI of the subject of the event to be matched

subjecttype - The URI of the type of subject of the event to be matched

predicate - The URI of the predicate of the event to be matched

object - The Object of the event to be matched. It depends on the implementer of this method how to match the object.

confidence - The confidence of the event to be matched

expiration - The expiration time of the event to be matched

provider - The context provider of the event to be matched

tstamp - The timestamp in milliseconds of the event to be matched. If not null, only events with this specified timestamp will be returned, as long as it is inside the time range specified by tstinputto

tstto - The timestamp in milliseconds until which events are requested. Only events stored before this timestamp will be returned.

Returns:

The list of context events that matched the values passed as parameters.

removeOldEvents

public void removeOldEvents(long tst)

Description copied from interface: Backend

Removes all events from the underlying store that were received until the specified timestamp.

Specified by:

removeOldEvents in interface Backend

Parameters:

tst - The timestamp in milliseconds until which events are removed. A value of 0 does nothing.

setuAALParser

public void setuAALParser(MessageContentSerializer service)

Description copied from interface: Backend

Set the MessageContentSerializer universAAL Parser that can be used to serialize and parse RDF data to universAAL data and vice-versa. This might be helpful in many implementations, and allows the activator of the CHE to look for such service in OSGi, which should be provided by the mandatory component mw.data.serialization. There is no guarantee though that the parser is set before it is used in the implementation, so check for nulls. If an implementation of a Backend does not need to use such parser, leave its implementation of this method empty.

Specified by:

setuAALParser in interface Backend

Parameters:

service - The MessageContentSerializer service implementation found in OSGi