Module org.apache.jena.arq
Package org.apache.jena.sparql.core

Class DatasetImpl

java.lang.Object
org.apache.jena.sparql.core.DatasetImpl
All Implemented Interfaces:
Dataset, Transactional
Direct Known Subclasses:
DatasetOne
public class DatasetImpl extends 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 Details

    • 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 Details

    • 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

    • supportsTransactions

      public boolean supportsTransactions()
      Description copied from interface: Dataset
      Does this dataset support transactions? Supporting transactions means that the dataset implementation provides Dataset.begin(org.apache.jena.query.ReadWrite), Dataset.commit(), Dataset.end() which otherwise may throw UnsupportedOperationException.

      See Dataset.supportsTransactionAbort() for Dataset.abort(). A Dataset that provides functionality across independent systems can not provide all features strong guarantees. For example, they may use MRSW locking and some isolation control. Specifically, they do not necessarily provide Dataset.abort().

      In addition, check details of a specific implementation.

      Specified by:
      supportsTransactions 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()
      Description copied from interface: Transactional
      Start a transaction which is READ mode and which will switch to WRITE if an update is attempted but only if no intermediate transaction has performed an update.

      See Transactional.begin(TxnType) for more details an options.

      May not be implemented. See Transactional.begin(ReadWrite) is guaranteed to be provided.

      Specified by:
      begin in interface Transactional

    • 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

    • begin

      public void begin(ReadWrite mode)
      Description copied from interface: Dataset
      Start either a READ or WRITE transaction
      Specified by:
      begin in interface Dataset
      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

    • isInTransaction

      public boolean isInTransaction()
      Say whether a transaction is active
      Specified by:
      isInTransaction in interface Dataset
      Specified by:
      isInTransaction 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

    • asDatasetGraph

      public DatasetGraph asDatasetGraph()
      Description copied from interface: Dataset
      Get the dataset in graph form
      Specified by:
      asDatasetGraph in interface Dataset

    • getNamedModel

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

    • getNamedModel

      public Model getNamedModel(Resource uri)
      Description copied from interface: Dataset
      Get a graph by resource as a Jena Model
      Specified by:
      getNamedModel in interface Dataset

    • addNamedModel

      public Dataset addNamedModel(String uri, Model model)
      Description copied from interface: Dataset
      Add 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

    • addNamedModel

      public Dataset addNamedModel(Resource uri, Model model)
      Description copied from interface: Dataset
      Add 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(String uri)
      Description copied from interface: Dataset
      Remove a named graph.
      Specified by:
      removeNamedModel in interface Dataset
      Parameters:
      uri - the name of the graph to remove
      Returns:
      this Dataset for continued usage

    • removeNamedModel

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

    • replaceNamedModel

      public Dataset replaceNamedModel(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

    • replaceNamedModel

      public Dataset replaceNamedModel(Resource 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. This operation copies the statements from the model into the default graph of the dataset.
      Specified by:
      setDefaultModel in interface Dataset
      Parameters:
      model - the default graph to set
      Returns:
      this Dataset for continued usage

    • containsNamedModel

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

    • containsNamedModel

      public boolean containsNamedModel(Resource uri)
      Description copied from interface: Dataset
      Does the dataset contain a model named by the resource supplied?
      Specified by:
      containsNamedModel in interface Dataset

    • listNames

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

    • listModelNames

      public Iterator<Resource> listModelNames()
      Description copied from interface: Dataset
      List the names
      Specified by:
      listModelNames 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.