DatasetImpl (Apache Jena ARQ)

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.

Nested Class Summary
- Nested classes/interfaces inherited from interface org.apache.jena.sparql.core.Transactional
  Transactional.Promote

Constructor Summary

Constructors
Constructor and Description

DatasetImpl(Dataset ds)
Deprecated.

DatasetImpl(Model model)
Create a Dataset with the model as default model.

Constructors
Constructor and Description
`DatasetImpl(Dataset ds)` Deprecated.
`DatasetImpl(Model model)` Create a Dataset with the model as default model.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`abort()` Abort a transaction - finish the transaction and undo any changes (if a "write" transaction)
`Dataset`	`addNamedModel(String uri, Model model)` Set a named graph.
`DatasetGraph`	`asDatasetGraph()` Get the dataset in graph form
`void`	`begin()` 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.
`void`	`begin(ReadWrite mode)` Start either a READ or WRITE transaction
`void`	`begin(TxnType txnType)` Start a transaction. READ or WRITE transactions start in that state and do not change for the lifetime of the transaction.
`void`	`close()` Close the dataset, potentially releasing any associated resources.
`void`	`commit()` Commit a transaction - finish the transaction and make any changes permanent (if a "write" transaction)
`boolean`	`containsNamedModel(String uri)` Does the dataset contain a model with the name supplied?
`void`	`end()` Finish the transaction - if a write transaction and commit() has not been called, then abort
`Context`	`getContext()` Get the context associated with this dataset
`Model`	`getDefaultModel()` Get the default graph as a Jena Model
`Lock`	`getLock()` Get the lock for this dataset
`Model`	`getNamedModel(String uri)` Get a graph by name as a Jena Model
`Model`	`getUnionModel()` Get the graph which is the unionof all named graphs as a Jena Model
`boolean`	`isEmpty()`
`boolean`	`isInTransaction()` Say whether a transaction is active
`Iterator<String>`	`listNames()` List the names
`boolean`	`promote(Transactional.Promote txnType)` Attempt to promote a transaction from "read" mode to "write" and the transaction.
`Dataset`	`removeNamedModel(String uri)` Remove a named graph.
`Dataset`	`replaceNamedModel(String uri, Model model)` Change a named graph for another using the same name
`Dataset`	`setDefaultModel(Model model)` Set the default graph.
`boolean`	`supportsTransactionAbort()` Declare whether `Dataset.abort()` is supported.
`boolean`	`supportsTransactions()` 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`.
`ReadWrite`	`transactionMode()` Return the current mode of the transaction - "read" or "write".
`TxnType`	`transactionType()` Return the transaction type used in `begin(TxnType)`.
`static Dataset`	`wrap(DatasetGraph datasetGraph)` Wrap an existing DatasetGraph

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.jena.sparql.core.Transactional
promote

- 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.
  - DatasetImpl
```
@Deprecated
public DatasetImpl(Dataset ds)
```
    Deprecated.
    
    Create a Dataset with a copy of the structure of another one, while sharing the graphs themselves.
- 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 unionof 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
  - addNamedModel
```
public Dataset addNamedModel(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(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(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(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 Iterator<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.

Class DatasetImpl

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.jena.sparql.core.Transactional

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.jena.sparql.core.Transactional

Constructor Detail

DatasetImpl

DatasetImpl

Method Detail

wrap

getDefaultModel

getUnionModel

getLock

getContext

supportsTransactions

supportsTransactionAbort

begin

begin

begin

promote

transactionMode

transactionType

isInTransaction

commit

abort

end

asDatasetGraph

getNamedModel

addNamedModel

removeNamedModel

replaceNamedModel

setDefaultModel

containsNamedModel

listNames

close

isEmpty