DatasetGraphMapLink (Apache Jena ARQ)

java.lang.Object
- org.apache.jena.sparql.core.DatasetGraphBase
- - org.apache.jena.sparql.core.DatasetGraphBaseFind
  - - org.apache.jena.sparql.core.DatasetGraphCollection
    - - org.apache.jena.sparql.core.DatasetGraphMapLink

All Implemented Interfaces:

org.apache.jena.atlas.lib.Closeable, DatasetGraph, Transactional
```
public class DatasetGraphMapLink
extends DatasetGraphCollection
```
Implementation of a DatasetGraph as an extensible set of graphs where graphs are held by reference. Care is needed when manipulating their contents especially if they are also in another DatasetGraph.
See DatasetGraphMap for an implementation that copies graphs and so providing better isolation.
This class is best used for creating views

See Also:

DatasetGraphMap

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

Constructor Summary

Constructors
Constructor and Description
`DatasetGraphMapLink(Graph dftGraph)` A `DatasetGraph` that uses the given graph for the default graph and create in-memory graphs for named graphs as needed

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)
`void`	`addGraph(Node graphName, Graph graph)` Add the given graph to the dataset.
`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.
`static DatasetGraph`	`cloneStructure(DatasetGraph dsg)` Create a new `DatasetGraph` that copies the dataset structure of default graph and named graph and links to the graphs of the original `DatasetGraph`.
`static DatasetGraph`	`cloneStructure(DatasetGraph dsg, DatasetGraphFactory.GraphMaker graphMaker)` Create a new `DatasetGraph` that copies the dataset structure of default graph and named graph and links to the graphs of the original `DatasetGraph` Any new graphs needed are separate from the original dataset and created according to the `DatasetGraphFactory.GraphMaker`.
`void`	`close()` Close the dataset
`void`	`commit()` Commit a transaction - finish the transaction and make any changes permanent (if a "write" transaction)
`boolean`	`containsGraph(Node graphNode)` Does the DatasetGraph contain a specific named graph? Whether a dataset contains a graph if there are no triples is not defined - see the specific implementation.
`void`	`end()` Finish the transaction - if a write transaction and commit() has not been called, then abort
`Graph`	`getDefaultGraph()` Get the default graph as a Jena Graph
`Graph`	`getGraph(Node graphNode)` Get the graph named by graphNode : returns null when there is no such graph.
`boolean`	`isInTransaction()` Say whether inside a transaction.
`Iterator<Node>`	`listGraphNodes()` Iterate over all names of named graphs
`boolean`	`promote(Transactional.Promote txnType)` Attempt to promote a transaction from "read" mode to "write" and the transaction.
`void`	`removeGraph(Node graphName)` Remove all data associated with the named graph.
`void`	`setDefaultGraph(Graph g)` Set the default graph.
`long`	`size()` Get the size (number of named graphs) - may be -1 for unknown
`boolean`	`supportsTransactionAbort()` Declare whether `Transactional.abort()` is supported.
`boolean`	`supportsTransactions()` A `DatasetGraph` supports transactions if it provides `Transactional.begin()`/ `Transactional.commit()`/`Transactional.end()`.
`ReadWrite`	`transactionMode()` Return the current mode of the transaction - "read" or "write".
`TxnType`	`transactionType()` Return the transaction type used in `begin(TxnType)`.

Methods inherited from class org.apache.jena.sparql.core.DatasetGraphCollection
add, clear, delete

Methods inherited from class org.apache.jena.sparql.core.DatasetGraphBaseFind
find, findInUnionGraph, findNG, findQuadsInUnionGraph

Methods inherited from class org.apache.jena.sparql.core.DatasetGraphBase
add, contains, contains, delete, deleteAny, deleteAny, find, find, getContext, getLock, getUnionGraph, isEmpty, toString

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

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

- Constructor Detail
  - DatasetGraphMapLink
```
public DatasetGraphMapLink(Graph dftGraph)
```
    A DatasetGraph that uses the given graph for the default graph and create in-memory graphs for named graphs as needed
- Method Detail
  - cloneStructure
```
public static DatasetGraph cloneStructure(DatasetGraph dsg)
```
    Create a new DatasetGraph that copies the dataset structure of default graph and named graph and links to the graphs of the original DatasetGraph. Any new graphs needed are separate from the original dataset and created in-memory.
  - cloneStructure
```
public static DatasetGraph cloneStructure(DatasetGraph dsg,
                                          DatasetGraphFactory.GraphMaker graphMaker)
```
    Create a new DatasetGraph that copies the dataset structure of default graph and named graph and links to the graphs of the original DatasetGraph Any new graphs needed are separate from the original dataset and created according to the DatasetGraphFactory.GraphMaker.
  - commit
```
public void commit()
```
    Description copied from interface: Transactional
    
    Commit a transaction - finish the transaction and make any changes permanent (if a "write" transaction)
  - 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.
  - 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.
  - begin
```
public void begin(ReadWrite mode)
```
    Description copied from interface: Transactional
    
    Start either a READ or WRITE transaction.
  - 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.
  - abort
```
public void abort()
```
    Description copied from interface: Transactional
    
    Abort a transaction - finish the transaction and undo any changes (if a "write" transaction)
  - isInTransaction
```
public boolean isInTransaction()
```
    Description copied from interface: Transactional
    
    Say whether inside a transaction.
  - end
```
public void end()
```
    Description copied from interface: Transactional
    
    Finish the transaction - if a write transaction and commit() has not been called, then abort
  - 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.
  - 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.
  - supportsTransactions
```
public boolean supportsTransactions()
```
    Description copied from interface: DatasetGraph
    
    A DatasetGraph supports transactions if it provides Transactional.begin()/ Transactional.commit()/Transactional.end(). The core storage DatasetGraphs provide fully serialized transactions. A DatasetGraph that provides functionality across independent systems can not provide such strong guarantees. For example, it may use MRSW locking and some isolation control. Specifically, it would not necessarily provide Transactional.abort().
    See DatasetGraph.supportsTransactionAbort() for Transactional.abort(). In addition, check details of a specific implementation.
  - supportsTransactionAbort
```
public boolean supportsTransactionAbort()
```
    Description copied from interface: DatasetGraph
    
    Declare whether Transactional.abort() is supported. This goes along with clearing up after exceptions inside application transaction code.
  - containsGraph
```
public boolean containsGraph(Node graphNode)
```
    Description copied from interface: DatasetGraph
    
    Does the DatasetGraph contain a specific named graph? Whether a dataset contains a graph if there are no triples is not defined - see the specific implementation. Some datasets are "open" - they have all graphs even if no triples and this returns true always.
    
    Specified by:
    
    containsGraph in interface DatasetGraph
    
    Overrides:
    
    containsGraph in class DatasetGraphBase
    
    Returns:
    
    boolean
  - getDefaultGraph
```
public Graph getDefaultGraph()
```
    Description copied from interface: DatasetGraph
    
    Get the default graph as a Jena Graph
    
    Specified by:
    
    getDefaultGraph in interface DatasetGraph
    
    Specified by:
    
    getDefaultGraph in class DatasetGraphBase
  - getGraph
```
public Graph getGraph(Node graphNode)
```
    Description copied from interface: DatasetGraph
    
    Get the graph named by graphNode : returns null when there is no such graph. NB Whether a dataset contains a graph if there are no triples is not defined - see the specific implementation. Some datasets are "open" - they have all graphs even if no triples.
    
    Specified by:
    
    getGraph in interface DatasetGraph
    
    Specified by:
    
    getGraph in class DatasetGraphBase
  - addGraph
```
public void addGraph(Node graphName,
                     Graph graph)
```
    Description copied from interface: DatasetGraph
    
    Add the given graph to the dataset. Replaces any existing data for the named graph; to add data, get the graph and add triples to it, or add quads to the dataset. Do not assume that the same Java object is returned by DatasetGraph.getGraph(org.apache.jena.graph.Node)
    
    Specified by:
    
    addGraph in interface DatasetGraph
    
    Specified by:
    
    addGraph in class DatasetGraphBase
  - removeGraph
```
public void removeGraph(Node graphName)
```
    Description copied from interface: DatasetGraph
    
    Remove all data associated with the named graph. This will include prefixes associated with the graph.
    
    Specified by:
    
    removeGraph in interface DatasetGraph
    
    Specified by:
    
    removeGraph in class DatasetGraphBase
  - setDefaultGraph
```
public void setDefaultGraph(Graph g)
```
    Description copied from interface: DatasetGraph
    
    Set the default graph. Set the active graph if it was null. This replaces the contents default graph, not merge data into it. Do not assume that the same object is returned by DatasetGraph.getDefaultGraph()
    
    Specified by:
    
    setDefaultGraph in interface DatasetGraph
    
    Overrides:
    
    setDefaultGraph in class DatasetGraphBase
  - listGraphNodes
```
public Iterator<Node> listGraphNodes()
```
    Description copied from interface: DatasetGraph
    
    Iterate over all names of named graphs
    
    Specified by:
    
    listGraphNodes in interface DatasetGraph
    
    Specified by:
    
    listGraphNodes in class DatasetGraphCollection
  - size
```
public long size()
```
    Description copied from interface: DatasetGraph
    
    Get the size (number of named graphs) - may be -1 for unknown
    
    Specified by:
    
    size in interface DatasetGraph
    
    Overrides:
    
    size in class DatasetGraphBase
  - close
```
public void close()
```
    Description copied from interface: DatasetGraph
    
    Close the dataset
    
    Specified by:
    
    close in interface org.apache.jena.atlas.lib.Closeable
    
    Specified by:
    
    close in interface DatasetGraph
    
    Overrides:
    
    close in class DatasetGraphBase

Class DatasetGraphMapLink

Nested Class Summary

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

Constructor Summary

Method Summary

Methods inherited from class org.apache.jena.sparql.core.DatasetGraphCollection

Methods inherited from class org.apache.jena.sparql.core.DatasetGraphBaseFind

Methods inherited from class org.apache.jena.sparql.core.DatasetGraphBase

Methods inherited from class java.lang.Object

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

Constructor Detail

DatasetGraphMapLink

Method Detail

cloneStructure

cloneStructure

commit

begin

begin

begin

promote

abort

isInTransaction

end

transactionMode

transactionType

supportsTransactions

supportsTransactionAbort

containsGraph

getDefaultGraph

getGraph

addGraph

removeGraph

setDefaultGraph

listGraphNodes

size

close