Package org.apache.jena.sparql.core

Class DatasetImpl

  • All Implemented Interfaces:
    Dataset, Transactional
    Direct Known Subclasses:
    DatasetOne
    public class DatasetImpl
extends java.lang.Object
implements Dataset
    An implementation of a Dataset. This is the "usual" implementation based on wrapping a DatasetGraph and providing an adapter layer from Model/Resource to Graph/Node The characteristics of this class depend on the characteristics of DatasetGraph.

    • Constructor Detail

      • DatasetImpl

        public DatasetImpl​(Model model)
        Create a Dataset with the model as default model. Named models must be explicitly added to identify the storage to be used.

    • Method Detail

      • wrap

        public static Dataset wrap​(DatasetGraph datasetGraph)
        Wrap an existing DatasetGraph

      • getDefaultModel

        public Model getDefaultModel()
        Description copied from interface: Dataset
        Get the default graph as a Jena Model
        Specified by:
        getDefaultModel in interface Dataset

      • getUnionModel

        public Model getUnionModel()
        Description copied from interface: Dataset
        Get the graph which is the union of all named graphs as a Jena Model
        Specified by:
        getUnionModel in interface Dataset

      • getLock

        public Lock getLock()
        Description copied from interface: Dataset
        Get the lock for this dataset
        Specified by:
        getLock in interface Dataset

      • getContext

        public Context getContext()
        Description copied from interface: Dataset
        Get the context associated with this dataset
        Specified by:
        getContext in interface Dataset

      • supportsTransactionAbort

        public boolean supportsTransactionAbort()
        Description copied from interface: Dataset
        Declare whether Dataset.abort() is supported. This goes along with clearing up after exceptions inside application transaction code.
        Specified by:
        supportsTransactionAbort in interface Dataset

      • begin

        public void begin​(TxnType txnType)
        Description copied from interface: Transactional
        Start a transaction.
        READ or WRITE transactions start in that state and do not change for the lifetime of the transaction.
        • WRITE: this guarantees a WRITE will complete if commit() is called. The same as begin(ReadWrite.WRITE).
        • READ: the transaction can not promote to WRITE,ensuring read-only access to the data. The same as begin(ReadWrite.READ).
        • READ_PROMOTE: the transaction will go from "read" to "write" if an update is attempted and if the dataset has not been changed by another write transaction. See also Transactional.promote().
        • READ_COMMITTED_PROMOTE: Use this with care. The promotion will succeed but changes from other transactions become visible.
        Read committed: at the point transaction attempts promotion from "read" to "write", the system checks if the dataset has change since the transaction started (called begin). If READ_PROMOTE, the dataset must not have changed; if READ_COMMITTED_PROMOTE any intermediate changes are visible but the application can not assume any data it has read in the transaction is the same as it was at the point the transaction started.

        This operation is optional and some implementations may throw a JenaTransactionException exception for some or all TxnType values.

        See Transactional.begin(ReadWrite) for a form that is required of implementations.

        Specified by:
        begin in interface Transactional

      • promote

        public boolean promote​(Transactional.Promote txnType)
        Description copied from interface: Transactional
        Attempt to promote a transaction from "read" mode to "write" and the transaction. This method allows the form of promotion to be specified. The transaction must not have been started with READ, which is read-only.

        An argument of READ_PROMOTE treats the promotion as if the transaction was started with READ_PROMOTE (any other writer commiting since the transaction started blocks promotion) and READ_COMMITTED_PROMOTE treats the promotion as if the transaction was started with READ_COMMITTED_PROMOTE (intemediate writer commits become visible).

        Returns "true" if the transaction is in write mode after the call. The method always succeeds of the transaction is already "write".

        This method returns true if a READ_PROMOTE or READ_COMMITTED_PROMOTE is promoted.

        This method returns false if a READ_PROMOTE can't be promoted - the transaction is still valid and in "read" mode.

        This method throws an exception if there is an attempt to promote a READ transaction.

        Specified by:
        promote in interface Transactional

      • transactionMode

        public ReadWrite transactionMode()
        Description copied from interface: Transactional
        Return the current mode of the transaction - "read" or "write". If the caller is not in a transaction, this method returns null.
        Specified by:
        transactionMode in interface Transactional

      • transactionType

        public TxnType transactionType()
        Description copied from interface: Transactional
        Return the transaction type used in begin(TxnType). If the caller is not in a transaction, this method returns null.
        Specified by:
        transactionType in interface Transactional

      • commit

        public void commit()
        Description copied from interface: Dataset
        Commit a transaction - finish the transaction and make any changes permanent (if a "write" transaction)
        Specified by:
        commit in interface Dataset
        Specified by:
        commit in interface Transactional

      • abort

        public void abort()
        Description copied from interface: Dataset
        Abort a transaction - finish the transaction and undo any changes (if a "write" transaction)
        Specified by:
        abort in interface Dataset
        Specified by:
        abort in interface Transactional

      • end

        public void end()
        Description copied from interface: Dataset
        Finish the transaction - if a write transaction and commit() has not been called, then abort
        Specified by:
        end in interface Dataset
        Specified by:
        end in interface Transactional

      • getNamedModel

        public Model getNamedModel​(java.lang.String uri)
        Description copied from interface: Dataset
        Get a graph by name as a Jena Model
        Specified by:
        getNamedModel in interface Dataset

      • addNamedModel

        public Dataset addNamedModel​(java.lang.String uri,
                             Model model)
        Description copied from interface: Dataset
        Set a named graph.
        Specified by:
        addNamedModel in interface Dataset
        Parameters:
        uri - the name of the graph to set
        model - the graph to set
        Returns:
        this Dataset for continued usage

      • removeNamedModel

        public Dataset removeNamedModel​(java.lang.String uri)
        Description copied from interface: Dataset
        Remove a named graph.
        Specified by:
        removeNamedModel in interface Dataset
        Parameters:
        uri - the name of the gaph to remove
        Returns:
        this Dataset for continued usage

      • replaceNamedModel

        public Dataset replaceNamedModel​(java.lang.String uri,
                                 Model model)
        Description copied from interface: Dataset
        Change a named graph for another using the same name
        Specified by:
        replaceNamedModel in interface Dataset
        Parameters:
        uri - the name of the graph to replace
        model - the graph with which to replace it
        Returns:
        this Dataset for continued usage

      • setDefaultModel

        public Dataset setDefaultModel​(Model model)
        Description copied from interface: Dataset
        Set the default graph. Can be set to null for none.
        Specified by:
        setDefaultModel in interface Dataset
        Parameters:
        model - the default graph to set
        Returns:
        this Dataset for continued usage

      • containsNamedModel

        public boolean containsNamedModel​(java.lang.String uri)
        Description copied from interface: Dataset
        Does the dataset contain a model with the name supplied?
        Specified by:
        containsNamedModel in interface Dataset

      • listNames

        public java.util.Iterator<java.lang.String> listNames()
        Description copied from interface: Dataset
        List the names
        Specified by:
        listNames in interface Dataset

      • close

        public void close()
        Description copied from interface: Dataset
        Close the dataset, potentially releasing any associated resources. The dataset can not be used for query after this call.
        Specified by:
        close in interface Dataset

      • isEmpty

        public boolean isEmpty()
        Specified by:
        isEmpty in interface Dataset
        Returns:
        Whether this Dataset is empty of triples, whether in the default graph or in any named graph.