Example #1
0
 def __init__(self, configuration=None, identifier=None):
     """
     identifier: URIRef of the Store. Defaults to CWD
     configuration: string containing infomation open can use to
     connect to datastore.
     """
     self.__node_pickler = None
     self.dispatcher = Dispatcher()
     if configuration:
         self.open(configuration)
 def __init__(self, configuration=None, identifier=None):
     """
     identifier: URIRef of the Store. Defaults to CWD
     configuration: string containing infomation open can use to
     connect to datastore.
     """
     self.__node_pickler = None
     self.dispatcher = Dispatcher()
     if configuration:
         self.open(configuration)
Example #3
0
 def __init__(self, store, filename):
     self.stream = file(filename, "rb")
     self.store = store
     dispatcher = Dispatcher()
     dispatcher.subscribe(TripleAddedEvent, self.add)
     dispatcher.subscribe(TripleRemovedEvent, self.remove)
     dispatcher.subscribe(StoreCreatedEvent, self.store_created)
     loads = store.node_pickler.loads
     dispatch = dispatcher.dispatch
     lines = []
     for line in self.stream:
         if line == "\n":
             try:
                 event = loads("".join(lines))
                 dispatch(event)
                 lines = []
             except Exception, e:
                 _logger.exception(e)
                 _logger.debug("lines: '%s'" % lines)
                 lines = []
         else:
             lines.append(line)
Example #4
0
 def __init__(self, store, filename):
     self.stream = file(filename, "rb")
     self.store = store
     dispatcher = Dispatcher()
     dispatcher.subscribe(TripleAddedEvent, self.add)
     dispatcher.subscribe(TripleRemovedEvent, self.remove)
     dispatcher.subscribe(StoreCreatedEvent, self.store_created)
     loads = store.node_pickler.loads
     dispatch = dispatcher.dispatch
     lines = []
     for line in self.stream:
         if line=="\n":
             try:
                 event = loads("".join(lines))
                 dispatch(event)
                 lines = []
             except Exception, e:
                 _logger.exception(e)
                 _logger.debug("lines: '%s'" % lines)
                 lines = []
         else:
             lines.append(line)
class Store(object):
    # Properties
    context_aware = False
    formula_aware = False
    transaction_aware = False
    batch_unification = False

    def __init__(self, configuration=None, identifier=None):
        """
        identifier: URIRef of the Store. Defaults to CWD
        configuration: string containing infomation open can use to
        connect to datastore.
        """
        self.__node_pickler = None
        self.dispatcher = Dispatcher()
        if configuration:
            self.open(configuration)

    def __get_node_pickler(self):
        if self.__node_pickler is None:
            from rdflib.term import URIRef
            from rdflib.term import BNode
            from rdflib.term import Literal
            from rdflib.graph import Graph, QuotedGraph, GraphValue
            from rdflib.term import Variable
            from rdflib.term import Statement
            self.__node_pickler = np = NodePickler()
            np.register(self, "S")
            np.register(URIRef, "U")
            np.register(BNode, "B")
            np.register(Literal, "L")
            np.register(Graph, "G")
            np.register(QuotedGraph, "Q")
            np.register(Variable, "V")
            np.register(Statement, "s")
            np.register(GraphValue, "v")
        return self.__node_pickler
    node_pickler = property(__get_node_pickler)

    # Database management methods
    def create(self, configuration):
        self.dispatcher.dispatch(
            StoreCreatedEvent(configuration=configuration))

    def open(self, configuration, create=False):
        """
        Opens the store specified by the configuration string. If
        create is True a store will be created if it does not already
        exist. If create is False and a store does not already exist
        an exception is raised. An exception is also raised if a store
        exists, but there is insufficient permissions to open the
        store.  This should return one of:
        VALID_STORE, CORRUPTED_STORE, or NO_STORE
        """
        return UNKNOWN

    def close(self, commit_pending_transaction=False):
        """
        This closes the database connection. The commit_pending_transaction
        parameter specifies whether to commit all pending transactions before
        closing (if the store is transactional).
        """

    def destroy(self, configuration):
        """
        This destroys the instance of the store identified by the
        configuration string.
        """

    def gc(self):
        """
        Allows the store to perform any needed garbage collection
        """
        pass

    # RDF APIs
    def add(self, (subject, predicate, object), context, quoted=False):
Example #6
0
class Store(object):
    #Properties
    context_aware = False
    formula_aware = False
    transaction_aware = False
    batch_unification = False
    def __init__(self, configuration=None, identifier=None):
        """
        identifier: URIRef of the Store. Defaults to CWD
        configuration: string containing infomation open can use to
        connect to datastore.
        """
        self.__node_pickler = None
        self.dispatcher = Dispatcher()
        if configuration:
            self.open(configuration)

    def __get_node_pickler(self):
        if self.__node_pickler is None:
            from rdflib.term import URIRef
            from rdflib.term import BNode
            from rdflib.term import Literal
            from rdflib.graph import Graph, QuotedGraph, GraphValue
            from rdflib.term import Variable
            from rdflib.term import Statement
            self.__node_pickler = np = NodePickler()
            np.register(self, "S")
            np.register(URIRef, "U")
            np.register(BNode, "B")
            np.register(Literal, "L")
            np.register(Graph, "G")
            np.register(QuotedGraph, "Q")
            np.register(Variable, "V")
            np.register(Statement, "s")
            np.register(GraphValue, "v")
        return self.__node_pickler
    node_pickler = property(__get_node_pickler)

    #Database management methods
    def create(self, configuration):
        self.dispatcher.dispatch(StoreCreatedEvent(configuration=configuration))

    def open(self, configuration, create=False):
        """
        Opens the store specified by the configuration string. If
        create is True a store will be created if it does not already
        exist. If create is False and a store does not already exist
        an exception is raised. An exception is also raised if a store
        exists, but there is insufficient permissions to open the
        store.  This should return one of VALID_STORE,CORRUPTED_STORE,or NO_STORE
        """
        return UNKNOWN

    def close(self, commit_pending_transaction=False):
        """
        This closes the database connection. The commit_pending_transaction parameter specifies whether to
        commit all pending transactions before closing (if the store is transactional).
        """

    def destroy(self, configuration):
        """
        This destroys the instance of the store identified by the configuration string.
        """

    def gc(self):
        """
        Allows the store to perform any needed garbage collection
        """
        pass

    #RDF APIs
    def add(self, (subject, predicate, object), context, quoted=False):
Example #7
0
class Store(object):
    #Properties
    context_aware = False
    formula_aware = False
    transaction_aware = False
    batch_unification = False
    def __init__(self, configuration=None, identifier=None):
        """
        identifier: URIRef of the Store. Defaults to CWD
        configuration: string containing infomation open can use to
        connect to datastore.
        """
        self.__node_pickler = None
        self.dispatcher = Dispatcher()
        if configuration:
            self.open(configuration)

    def __get_node_pickler(self):
        if self.__node_pickler is None:
            from rdflib.store.NodePickler import NodePickler
            from rdflib.URIRef import URIRef
            from rdflib.BNode import BNode
            from rdflib.Literal import Literal
            from rdflib.Graph import Graph, QuotedGraph, GraphValue
            from rdflib.Variable import Variable
            from rdflib.Statement import Statement
            self.__node_pickler = np = NodePickler()
            np.register(self, "S")
            np.register(URIRef, "U")
            np.register(BNode, "B")
            np.register(Literal, "L")
            np.register(Graph, "G")
            np.register(QuotedGraph, "Q")
            np.register(Variable, "V")
            np.register(Statement, "s")
            np.register(GraphValue, "v")
        return self.__node_pickler
    node_pickler = property(__get_node_pickler)

    #Database management methods
    def create(self, configuration):
        self.dispatcher.dispatch(StoreCreatedEvent(configuration=configuration))
        
    def open(self, configuration, create=False):
        """
        Opens the store specified by the configuration string. If
        create is True a store will be created if it does not already
        exist. If create is False and a store does not already exist
        an exception is raised. An exception is also raised if a store
        exists, but there is insufficient permissions to open the
        store.  This should return one of VALID_STORE,CORRUPTED_STORE,or NO_STORE
        """
        return UNKNOWN

    def close(self, commit_pending_transaction=False):
        """
        This closes the database connection. The commit_pending_transaction parameter specifies whether to
        commit all pending transactions before closing (if the store is transactional).
        """

    def destroy(self, configuration):
        """
        This destroys the instance of the store identified by the configuration string.
        """

    def gc(self):
        """
        Allows the store to perform any needed garbage collection
        """
        pass

    def sparql_query(self,
                     queryString,
                     queryObj,
                     graph,
                     dataSetBase,
                     extensionFunctions,
                     initBindings={},
                     initNs={},
                     DEBUG=False):
        """
        The default 'native' SPARQL implementation is based on sparql-p's expansion trees
        layered on top of the read-only RDF APIs of the underlying store 
        """
        from rdflib.sparql.Algebra import TopEvaluate
        from rdflib.QueryResult import QueryResult
        from rdflib import plugin
        rt =   TopEvaluate(queryObj,
                           graph,
                           initBindings,
                           DEBUG=DEBUG,
                           dataSetBase=dataSetBase,
                           extensionFunctions=extensionFunctions)
        return plugin.get('SPARQLQueryResult',QueryResult)(rt)

    #RDF APIs
    def add(self, (subject, predicate, object), context, quoted=False):
Example #8
0
class Store(object):
    # Properties
    context_aware = False
    formula_aware = False
    transaction_aware = False
    graph_aware = False

    def __init__(self, configuration=None, identifier=None):
        """
        identifier: URIRef of the Store. Defaults to CWD
        configuration: string containing infomation open can use to
        connect to datastore.
        """
        self.__node_pickler = None
        self.dispatcher = Dispatcher()
        if configuration:
            self.open(configuration)

    def __get_node_pickler(self):
        if self.__node_pickler is None:
            from rdflib.term import URIRef
            from rdflib.term import BNode
            from rdflib.term import Literal
            from rdflib.graph import Graph, QuotedGraph
            from rdflib.term import Variable
            from rdflib.term import Statement

            self.__node_pickler = np = NodePickler()
            np.register(self, "S")
            np.register(URIRef, "U")
            np.register(BNode, "B")
            np.register(Literal, "L")
            np.register(Graph, "G")
            np.register(QuotedGraph, "Q")
            np.register(Variable, "V")
            np.register(Statement, "s")
        return self.__node_pickler

    node_pickler = property(__get_node_pickler)

    # Database management methods
    def create(self, configuration):
        self.dispatcher.dispatch(StoreCreatedEvent(configuration=configuration))

    def open(self, configuration, create=False):
        """
        Opens the store specified by the configuration string. If
        create is True a store will be created if it does not already
        exist. If create is False and a store does not already exist
        an exception is raised. An exception is also raised if a store
        exists, but there is insufficient permissions to open the
        store.  This should return one of:
        VALID_STORE, CORRUPTED_STORE, or NO_STORE
        """
        return UNKNOWN

    def close(self, commit_pending_transaction=False):
        """
        This closes the database connection. The commit_pending_transaction
        parameter specifies whether to commit all pending transactions before
        closing (if the store is transactional).
        """

    def destroy(self, configuration):
        """
        This destroys the instance of the store identified by the
        configuration string.
        """

    def gc(self):
        """
        Allows the store to perform any needed garbage collection
        """
        pass

    # RDF APIs
    def add(self, triple, context, quoted=False):
        """
        Adds the given statement to a specific context or to the model. The
        quoted argument is interpreted by formula-aware stores to indicate
        this statement is quoted/hypothetical It should be an error to not
        specify a context and have the quoted argument be True. It should also
        be an error for the quoted argument to be True when the store is not
        formula-aware.
        """
        self.dispatcher.dispatch(TripleAddedEvent(triple=triple, context=context))

    def addN(self, quads):
        """
        Adds each item in the list of statements to a specific context. The
        quoted argument is interpreted by formula-aware stores to indicate this
        statement is quoted/hypothetical. Note that the default implementation
        is a redirect to add
        """
        for s, p, o, c in quads:
            assert c is not None, "Context associated with %s %s %s is None!" % (
                s,
                p,
                o,
            )
            self.add((s, p, o), c)

    def remove(self, triple, context=None):
        """ Remove the set of triples matching the pattern from the store """
        self.dispatcher.dispatch(TripleRemovedEvent(triple=triple, context=context))

    def triples_choices(self, triple, context=None):
        """
        A variant of triples that can take a list of terms instead of a single
        term in any slot.  Stores can implement this to optimize the response
        time from the default 'fallback' implementation, which will iterate
        over each term in the list and dispatch to triples
        """
        subject, predicate, object_ = triple
        if isinstance(object_, list):
            assert not isinstance(subject, list), "object_ / subject are both lists"
            assert not isinstance(predicate, list), "object_ / predicate are both lists"
            if object_:
                for obj in object_:
                    for (s1, p1, o1), cg in self.triples(
                        (subject, predicate, obj), context
                    ):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples(
                    (subject, predicate, None), context
                ):
                    yield (s1, p1, o1), cg

        elif isinstance(subject, list):
            assert not isinstance(predicate, list), "subject / predicate are both lists"
            if subject:
                for subj in subject:
                    for (s1, p1, o1), cg in self.triples(
                        (subj, predicate, object_), context
                    ):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples(
                    (None, predicate, object_), context
                ):
                    yield (s1, p1, o1), cg

        elif isinstance(predicate, list):
            assert not isinstance(subject, list), "predicate / subject are both lists"
            if predicate:
                for pred in predicate:
                    for (s1, p1, o1), cg in self.triples(
                        (subject, pred, object_), context
                    ):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples((subject, None, object_), context):
                    yield (s1, p1, o1), cg

    def triples(self, triple_pattern, context=None):
        """
        A generator over all the triples matching the pattern. Pattern can
        include any objects for used for comparing against nodes in the store,
        for example, REGEXTerm, URIRef, Literal, BNode, Variable, Graph,
        QuotedGraph, Date? DateRange?

        :param context: A conjunctive query can be indicated by either
                        providing a value of None, or a specific context can be
                        queries by passing a Graph instance (if store is context aware).
        """
        subject, predicate, object = triple_pattern

    # variants of triples will be done if / when optimization is needed

    def __len__(self, context=None):
        """
        Number of statements in the store. This should only account for non-
        quoted (asserted) statements if the context is not specified,
        otherwise it should return the number of statements in the formula or
        context given.

        :param context: a graph instance to query or None
        """

    def contexts(self, triple=None):
        """
        Generator over all contexts in the graph. If triple is specified,
        a generator over all contexts the triple is in.

        if store is graph_aware, may also return empty contexts

        :returns: a generator over Nodes
        """

    def query(self, query, initNs, initBindings, queryGraph, **kwargs):
        """
        If stores provide their own SPARQL implementation, override this.

        queryGraph is None, a URIRef or '__UNION__'
        If None the graph is specified in the query-string/object
        If URIRef it specifies the graph to query,
        If  '__UNION__' the union of all named graphs should be queried
        (This is used by ConjunctiveGraphs
        Values other than None obviously only makes sense for
        context-aware stores.)

        """

        raise NotImplementedError

    def update(self, update, initNs, initBindings, queryGraph, **kwargs):
        """
        If stores provide their own (SPARQL) Update implementation,
        override this.

        queryGraph is None, a URIRef or '__UNION__'
        If None the graph is specified in the query-string/object
        If URIRef it specifies the graph to query,
        If  '__UNION__' the union of all named graphs should be queried
        (This is used by ConjunctiveGraphs
        Values other than None obviously only makes sense for
        context-aware stores.)

        """

        raise NotImplementedError

    # Optional Namespace methods

    def bind(self, prefix, namespace):
        """ """

    def prefix(self, namespace):
        """ """

    def namespace(self, prefix):
        """ """

    def namespaces(self):
        """ """
        if False:
            yield None

    # Optional Transactional methods

    def commit(self):
        """ """

    def rollback(self):
        """ """

    # Optional graph methods

    def add_graph(self, graph):
        """
        Add a graph to the store, no effect if the graph already
        exists.
        :param graph: a Graph instance
        """
        raise Exception("Graph method called on non-graph_aware store")

    def remove_graph(self, graph):
        """
        Remove a graph from the store, this shoud also remove all
        triples in the graph

        :param graphid: a Graph instance
        """
        raise Exception("Graph method called on non-graph_aware store")
Example #9
0
 def dispatcher(self):
     if not hasattr(self, '_v_dispatcher'):
         self._v_dispatcher = Dispatcher()
     return self._v_dispatcher
Example #10
0
class Store(object):
    # Properties
    context_aware = False
    formula_aware = False
    transaction_aware = False
    graph_aware = False

    def __init__(self, configuration=None, identifier=None):
        """
        identifier: URIRef of the Store. Defaults to CWD
        configuration: string containing infomation open can use to
        connect to datastore.
        """
        self.__node_pickler = None
        self.dispatcher = Dispatcher()
        if configuration:
            self.open(configuration)

    def __get_node_pickler(self):
        if self.__node_pickler is None:
            from rdflib.term import URIRef
            from rdflib.term import BNode
            from rdflib.term import Literal
            from rdflib.graph import Graph, QuotedGraph
            from rdflib.term import Variable
            from rdflib.term import Statement
            self.__node_pickler = np = NodePickler()
            np.register(self, "S")
            np.register(URIRef, "U")
            np.register(BNode, "B")
            np.register(Literal, "L")
            np.register(Graph, "G")
            np.register(QuotedGraph, "Q")
            np.register(Variable, "V")
            np.register(Statement, "s")
        return self.__node_pickler
    node_pickler = property(__get_node_pickler)

    # Database management methods
    def create(self, configuration):
        self.dispatcher.dispatch(
            StoreCreatedEvent(configuration=configuration))

    def open(self, configuration, create=False):
        """
        Opens the store specified by the configuration string. If
        create is True a store will be created if it does not already
        exist. If create is False and a store does not already exist
        an exception is raised. An exception is also raised if a store
        exists, but there is insufficient permissions to open the
        store.  This should return one of:
        VALID_STORE, CORRUPTED_STORE, or NO_STORE
        """
        return UNKNOWN

    def close(self, commit_pending_transaction=False):
        """
        This closes the database connection. The commit_pending_transaction
        parameter specifies whether to commit all pending transactions before
        closing (if the store is transactional).
        """

    def destroy(self, configuration):
        """
        This destroys the instance of the store identified by the
        configuration string.
        """

    def gc(self):
        """
        Allows the store to perform any needed garbage collection
        """
        pass

    # RDF APIs
    def add(self, triple, context, quoted=False):
        """
        Adds the given statement to a specific context or to the model. The
        quoted argument is interpreted by formula-aware stores to indicate
        this statement is quoted/hypothetical It should be an error to not
        specify a context and have the quoted argument be True. It should also
        be an error for the quoted argument to be True when the store is not
        formula-aware.
        """
        self.dispatcher.dispatch(
            TripleAddedEvent(
                triple=triple, context=context))

    def addN(self, quads):
        """
        Adds each item in the list of statements to a specific context. The
        quoted argument is interpreted by formula-aware stores to indicate this
        statement is quoted/hypothetical. Note that the default implementation
        is a redirect to add
        """
        for s, p, o, c in quads:
            assert c is not None, \
                "Context associated with %s %s %s is None!" % (s, p, o)
            self.add((s, p, o), c)

    def remove(self, triple, context=None):
        """ Remove the set of triples matching the pattern from the store """
        self.dispatcher.dispatch(
            TripleRemovedEvent(
                triple=triple, context=context))

    def triples_choices(self, triple, context=None):
        """
        A variant of triples that can take a list of terms instead of a single
        term in any slot.  Stores can implement this to optimize the response
        time from the default 'fallback' implementation, which will iterate
        over each term in the list and dispatch to triples
        """
        subject, predicate, object_ = triple
        if isinstance(object_, list):
            assert not isinstance(
                subject, list), "object_ / subject are both lists"
            assert not isinstance(
                predicate, list), "object_ / predicate are both lists"
            if object_:
                for obj in object_:
                    for (s1, p1, o1), cg in self.triples(
                            (subject, predicate, obj), context):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples(
                        (subject, predicate, None), context):
                    yield (s1, p1, o1), cg

        elif isinstance(subject, list):
            assert not isinstance(
                predicate, list), "subject / predicate are both lists"
            if subject:
                for subj in subject:
                    for (s1, p1, o1), cg in self.triples(
                            (subj, predicate, object_), context):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples(
                        (None, predicate, object_), context):
                    yield (s1, p1, o1), cg

        elif isinstance(predicate, list):
            assert not isinstance(
                subject, list), "predicate / subject are both lists"
            if predicate:
                for pred in predicate:
                    for (s1, p1, o1), cg in self.triples(
                            (subject, pred, object_), context):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples(
                        (subject, None, object_), context):
                    yield (s1, p1, o1), cg

    def triples(self, triple_pattern, context=None):
        """
        A generator over all the triples matching the pattern. Pattern can
        include any objects for used for comparing against nodes in the store,
        for example, REGEXTerm, URIRef, Literal, BNode, Variable, Graph,
        QuotedGraph, Date? DateRange?

        :param context: A conjunctive query can be indicated by either
        providing a value of None, or a specific context can be
        queries by passing a Graph instance (if store is context aware).
        """
        subject, predicate, object = triple_pattern

    # variants of triples will be done if / when optimization is needed

    def __len__(self, context=None):
        """
        Number of statements in the store. This should only account for non-
        quoted (asserted) statements if the context is not specified,
        otherwise it should return the number of statements in the formula or
        context given.

        :param context: a graph instance to query or None
        """

    def contexts(self, triple=None):
        """
        Generator over all contexts in the graph. If triple is specified,
        a generator over all contexts the triple is in.

        if store is graph_aware, may also return empty contexts

        :returns: a generator over Nodes
        """

    def query(self, query, initNs, initBindings, queryGraph, **kwargs):
        """
        If stores provide their own SPARQL implementation, override this.

        queryGraph is None, a URIRef or '__UNION__'
        If None the graph is specified in the query-string/object
        If URIRef it specifies the graph to query,
        If  '__UNION__' the union of all named graphs should be queried
        (This is used by ConjunctiveGraphs
        Values other than None obviously only makes sense for
        context-aware stores.)

        """

        raise NotImplementedError

    def update(self, update, initNs, initBindings, queryGraph, **kwargs):
        """
        If stores provide their own (SPARQL) Update implementation,
        override this.

        queryGraph is None, a URIRef or '__UNION__'
        If None the graph is specified in the query-string/object
        If URIRef it specifies the graph to query,
        If  '__UNION__' the union of all named graphs should be queried
        (This is used by ConjunctiveGraphs
        Values other than None obviously only makes sense for
        context-aware stores.)

        """

        raise NotImplementedError

    # Optional Namespace methods

    def bind(self, prefix, namespace):
        """ """

    def prefix(self, namespace):
        """ """

    def namespace(self, prefix):
        """ """

    def namespaces(self):
        """ """
        if False:
            yield None

    # Optional Transactional methods

    def commit(self):
        """ """

    def rollback(self):
        """ """

    # Optional graph methods

    def add_graph(self, graph):
        """
        Add a graph to the store, no effect if the graph already
        exists.
        :param graph: a Graph instance
        """
        raise Exception("Graph method called on non-graph_aware store")

    def remove_graph(self, graph):
        """
        Remove a graph from the store, this shoud also remove all
        triples in the graph

        :param graphid: a Graph instance
        """
        raise Exception("Graph method called on non-graph_aware store")
Example #11
0
class Store(object):
    #Properties
    context_aware = False
    formula_aware = False
    transaction_aware = False

    def __init__(self, configuration=None, identifier=None):
        """
        identifier: URIRef of the Store. Defaults to CWD
        configuration: string containing infomation open can use to
        connect to datastore.
        """
        self.__node_pickler = None
        self.dispatcher = Dispatcher()
        if configuration:
            self.open(configuration)

    def __get_node_pickler(self):
        if self.__node_pickler is None:
            from rdflib.store.NodePickler import NodePickler
            from rdflib.URIRef import URIRef
            from rdflib.BNode import BNode
            from rdflib.Literal import Literal
            from rdflib.Graph import Graph, QuotedGraph, GraphValue
            from rdflib.Variable import Variable
            from rdflib.Statement import Statement
            self.__node_pickler = np = NodePickler()
            np.register(self, "S")
            np.register(URIRef, "U")
            np.register(BNode, "B")
            np.register(Literal, "L")
            np.register(Graph, "G")
            np.register(QuotedGraph, "Q")
            np.register(Variable, "V")
            np.register(Statement, "s")
            np.register(GraphValue, "v")
        return self.__node_pickler

    node_pickler = property(__get_node_pickler)

    #Database management methods
    def create(self, configuration):
        self.dispatcher.dispatch(
            StoreCreatedEvent(configuration=configuration))

    def open(self, configuration, create=False):
        """
        Opens the store specified by the configuration string. If
        create is True a store will be created if it does not already
        exist. If create is False and a store does not already exist
        an exception is raised. An exception is also raised if a store
        exists, but there is insufficient permissions to open the
        store.  This should return one of VALID_STORE,CORRUPTED_STORE,or NO_STORE
        """
        return UNKNOWN

    def close(self, commit_pending_transaction=False):
        """
        This closes the database connection. The commit_pending_transaction parameter specifies whether to
        commit all pending transactions before closing (if the store is transactional).
        """

    def destroy(self, configuration):
        """
        This destroys the instance of the store identified by the configuration string.
        """

    def gc(self):
        """
        Allows the store to perform any needed garbage collection
        """
        pass

    #RDF APIs
    def add(self, xxx_todo_changeme, context, quoted=False):
        """
        Adds the given statement to a specific context or to the model. The quoted argument
        is interpreted by formula-aware stores to indicate this statement is quoted/hypothetical
        It should be an error to not specify a context and have the quoted argument be True.
        It should also be an error for the quoted argument to be True when the store is not formula-aware.
        """
        (subject, predicate, object) = xxx_todo_changeme
        self.dispatcher.dispatch(
            TripleAddedEvent(triple=(subject, predicate, object),
                             context=context))

    def addN(self, quads):
        """
       Adds each item in the list of statements to a specific context. The quoted argument
       is interpreted by formula-aware stores to indicate this statement is quoted/hypothetical.
       Note that the default implementation is a redirect to add
       """
        for s, p, o, c in quads:
            assert c is not None, "Context associated with %s %s %s is None!" % (
                s, p, o)
            self.add((s, p, o), c)

    def remove(self, xxx_todo_changeme1, context=None):
        """ Remove the set of triples matching the pattern from the store """
        (subject, predicate, object) = xxx_todo_changeme1
        self.dispatcher.dispatch(
            TripleRemovedEvent(triple=(subject, predicate, object),
                               context=context))

    def triples_choices(self, xxx_todo_changeme2, context=None):
        """
        A variant of triples that can take a list of terms instead of a single
        term in any slot.  Stores can implement this to optimize the response time
        from the default 'fallback' implementation, which will iterate
        over each term in the list and dispatch to tripless
        """
        (subject, predicate, object_) = xxx_todo_changeme2
        if isinstance(object_, list):
            assert not isinstance(subject,
                                  list), "object_ / subject are both lists"
            assert not isinstance(predicate,
                                  list), "object_ / predicate are both lists"
            if object_:
                for obj in object_:
                    for (s1, p1, o1), cg in self.triples(
                        (subject, predicate, obj), context):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples(
                    (subject, predicate, None), context):
                    yield (s1, p1, o1), cg

        elif isinstance(subject, list):
            assert not isinstance(predicate,
                                  list), "subject / predicate are both lists"
            if subject:
                for subj in subject:
                    for (s1, p1, o1), cg in self.triples(
                        (subj, predicate, object_), context):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples(
                    (None, predicate, object_), context):
                    yield (s1, p1, o1), cg

        elif isinstance(predicate, list):
            assert not isinstance(subject,
                                  list), "predicate / subject are both lists"
            if predicate:
                for pred in predicate:
                    for (s1, p1, o1), cg in self.triples(
                        (subject, pred, object_), context):
                        yield (s1, p1, o1), cg
            else:
                for (s1, p1, o1), cg in self.triples((subject, None, object_),
                                                     context):
                    yield (s1, p1, o1), cg

    def triples(self, xxx_todo_changeme3, context=None):
        """
        A generator over all the triples matching the pattern. Pattern can
        include any objects for used for comparing against nodes in the store, for
        example, REGEXTerm, URIRef, Literal, BNode, Variable, Graph, QuotedGraph, Date? DateRange?

        A conjunctive query can be indicated by either providing a value of None
        for the context or the identifier associated with the Conjunctive Graph (if it's context aware).
        """
        (subject, predicate, object) = xxx_todo_changeme3
        pass

    # variants of triples will be done if / when optimization is needed

    def __len__(self, context=None):
        """
        Number of statements in the store. This should only account for non-quoted (asserted) statements
        if the context is not specified, otherwise it should return the number of statements in the formula or context given.
        """
        pass

    def contexts(self, triple=None):
        """
        Generator over all contexts in the graph. If triple is specified, a generator over all
        contexts the triple is in.
        """
        pass

    # Optional Namespace methods

    def bind(self, prefix, namespace):
        """ """
        pass

    def prefix(self, namespace):
        """ """
        pass

    def namespace(self, prefix):
        """ """
        pass

    def namespaces(self):
        """ """
        pass

    # Optional Transactional methods

    def commit(self):
        """ """
        pass

    def rollback(self):
        """ """
        pass