org.eclipse.rdf4j.sail.helpers

## Class SailConnectionWrapper

- java.lang.Object
- - org.eclipse.rdf4j.sail.helpers.SailConnectionWrapper

- All Implemented Interfaces:
    AutoCloseable, FederatedServiceResolverClient, SailConnection
  Direct Known Subclasses:
    NotifyingSailConnectionWrapper, VerySimpleRdfsBackwardsChainingConnection

      public class SailConnectionWrapper
      extends Object
      implements SailConnection, FederatedServiceResolverClient

  An implementation of the SailConnection interface that wraps another SailConnection object and forwards any method calls to the wrapped connection.
  Author:
    Jeen Broekstra

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `SailConnectionWrapper(SailConnection wrappedCon)` Creates a new TransactionWrapper object that wraps the supplied connection.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addStatement(Resource subj, IRI pred, Value obj, Resource... contexts)` Adds a statement to the store.
    `void` | `addStatement(UpdateContext modify, Resource subj, IRI pred, Value obj, Resource... contexts)` Adds a statement to the store.
    `void` | `begin()` Begins a transaction requiring `SailConnection.commit()` or `SailConnection.rollback()` to be called to close the transaction.
    `void` | `begin(IsolationLevel level)` Begins a transaction with the specified `IsolationLevel` level, requiring `SailConnection.commit()` or `SailConnection.rollback()` to be called to close the transaction.
    `void` | `clear(Resource... contexts)` Removes all statements from the specified/all contexts.
    `void` | `clearNamespaces()` Removes all namespace declarations from the repository.
    `void` | `close()` Closes the connection.
    `void` | `commit()` Commits any updates that have been performed since the last time `SailConnection.commit()` or `SailConnection.rollback()` was called.
    `void` | `endUpdate(UpdateContext modify)` Indicates that the given `op` will not be used in any call again.
    `CloseableIteration<? extends BindingSet,QueryEvaluationException>` | `evaluate(TupleExpr tupleExpr, Dataset dataset, BindingSet bindings, boolean includeInferred)` Evaluates the supplied TupleExpr on the data contained in this Sail object, using the (optional) dataset and supplied bindings as input parameters.
    `Explanation` | `explain(Explanation.Level level, TupleExpr tupleExpr, Dataset dataset, BindingSet bindings, boolean includeInferred, int timeoutSeconds)` Explain how the TupleExpr will be (or has been) executed/evaluated by returning a TupleExpr (which may or may not be the provided TupleExpr) that has gone through zero or more of the stages prior to and also including execution as specified by the provided level.
    `void` | `flush()` Flushes any pending updates and notify changes to listeners as appropriate.
    `CloseableIteration<? extends Resource,SailException>` | `getContextIDs()` Returns the set of all unique context identifiers that are used to store statements.
    `String` | `getNamespace(String prefix)` Gets the namespace that is associated with the specified prefix, if any.
    `CloseableIteration<? extends Namespace,SailException>` | `getNamespaces()` Gets the namespaces relevant to the data contained in this Sail object.
    `CloseableIteration<? extends Statement,SailException>` | `getStatements(Resource subj, IRI pred, Value obj, boolean includeInferred, Resource... contexts)` Gets all statements from the specified contexts that have a specific subject, predicate and/or object.
    `SailConnection` | `getWrappedConnection()` Gets the connection that is wrapped by this object.
    `boolean` | `hasStatement(Resource subj, IRI pred, Value obj, boolean includeInferred, Resource... contexts)` Determines if the store contains any statements from the specified contexts that have a specific subject, predicate and/or object.
    `boolean` | `isActive()` Indicates if a transaction is currently active on the connection.
    `boolean` | `isOpen()` Checks whether this SailConnection is open.
    `boolean` | `pendingRemovals()` Indicates if the Sail has any statement removal operations pending (not yet `flushed`) for the current transaction.
    `void` | `prepare()` Checks for an error state in the active transaction that would force the transaction to be rolled back.
    `Optional<TupleExpr>` | `prepareQuery(QueryLanguage ql, Query.QueryType type, String query, String baseURI)` Allows the SailConnection to bypass the standard query parser and provide its own internal `TupleExpr` implementation.
    `void` | `removeNamespace(String prefix)` Removes a namespace declaration by removing the association between a prefix and a namespace name.
    `void` | `removeStatement(UpdateContext modify, Resource subj, IRI pred, Value obj, Resource... contexts)` Removes all statements matching the specified subject, predicate and object from the repository.
    `void` | `removeStatements(Resource subj, IRI pred, Value obj, Resource... contexts)` Removes all statements matching the specified subject, predicate and object from the repository.
    `void` | `rollback()` Rolls back the transaction, discarding any uncommitted changes that have been made in this SailConnection.
    `void` | `setFederatedServiceResolver(FederatedServiceResolver resolver)` Sets the `FederatedServiceResolver` to use for this client.
    `void` | `setNamespace(String prefix, String name)` Sets the prefix for a namespace.
    `void` | `setTransactionSettings(TransactionSetting... settings)` Pass any transaction-specific settings to the SailConnection.
    `long` | `size(Resource... contexts)` Returns the number of (explicit) statements in the store, or in specific contexts.
    `long` | `size(Resource context)`
    `void` | `startUpdate(UpdateContext modify)` Signals the start of an update operation.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

    - ### Methods inherited from interface org.eclipse.rdf4j.sail.SailConnection

      `addStatement, addStatement, getStatements, removeStatement, removeStatements`

- - ### Constructor Detail

    - #### SailConnectionWrapper

          public SailConnectionWrapper(SailConnection wrappedCon)

      Creates a new TransactionWrapper object that wraps the supplied connection.

  - ### Method Detail

    - #### getWrappedConnection

          public SailConnection getWrappedConnection()

      Gets the connection that is wrapped by this object.
      Returns:
        The SailConnection object that was supplied to the constructor of this class.

    - #### setFederatedServiceResolver

          public void setFederatedServiceResolver(FederatedServiceResolver resolver)

      Description copied from interface: `FederatedServiceResolverClient`
      Sets the `FederatedServiceResolver` to use for this client.
      Specified by:
        `setFederatedServiceResolver` in interface `FederatedServiceResolverClient`
      Parameters:
        `resolver` - The resolver to use.

    - #### isOpen

          public boolean isOpen()
                         throws SailException

      Description copied from interface: `SailConnection`
      Checks whether this SailConnection is open. A SailConnection is open from the moment it is created until it is closed.
      Specified by:
        `isOpen` in interface `SailConnection`
      Throws:
        `SailException`
      See Also:
        `SailConnection.close()`

    - #### close

          public void close()
                     throws SailException

      Description copied from interface: `SailConnection`
      Closes the connection. Any updates that haven't been committed yet will be rolled back. The connection can no longer be used once it is closed.
      Specified by:
        `close` in interface `AutoCloseable`
      Specified by:
        `close` in interface `SailConnection`
      Throws:
        `SailException`

    - #### prepareQuery

          public Optional<TupleExpr> prepareQuery(QueryLanguage ql,
                                                  Query.QueryType type,
                                                  String query,
                                                  String baseURI)

      Description copied from interface: `SailConnection`
      Allows the SailConnection to bypass the standard query parser and provide its own internal `TupleExpr` implementation. By default this method returns an empty result, signaling that it will rely on the RDF4J query parser.
      Specified by:
        `prepareQuery` in interface `SailConnection`
      Parameters:
        `ql` - the query language.
        `type` - indicates if the supplied query is a graph, tuple, or boolean query
        `query` - the unparsed query string
        `baseURI` - the provided base URI. May be null or empty.
      Returns:
        an optional TupleExpr that represents a sail-specific version of the query, which `SailConnection.evaluate(org.eclipse.rdf4j.query.algebra.TupleExpr, org.eclipse.rdf4j.query.Dataset, org.eclipse.rdf4j.query.BindingSet, boolean)` can process. Returns `Optional.empty()` if the Sail does not provide its own query processing.

    - #### evaluate

          public CloseableIteration<? extends BindingSet,QueryEvaluationException> evaluate(TupleExpr tupleExpr,
                                                                                            Dataset dataset,
                                                                                            BindingSet bindings,
                                                                                            boolean includeInferred)
                                                                                     throws SailException

      Description copied from interface: `SailConnection`
      Evaluates the supplied TupleExpr on the data contained in this Sail object, using the (optional) dataset and supplied bindings as input parameters.
      Specified by:
        `evaluate` in interface `SailConnection`
      Parameters:
        `tupleExpr` - The tuple expression to evaluate.
        `dataset` - The dataset to use for evaluating the query, `null` to use the Sail's default dataset.
        `bindings` - A set of input parameters for the query evaluation. The keys reference variable names that should be bound to the value they map to.
        `includeInferred` - Indicates whether inferred triples are to be considered in the query result. If false, no inferred statements are returned; if true, inferred statements are returned if available
      Returns:
        The TupleQueryResult.
      Throws:
        `SailException` - If the Sail object encountered an error or unexpected situation internally.

    - #### getContextIDs

          public CloseableIteration<? extends Resource,SailException> getContextIDs()
                                                                             throws SailException

      Description copied from interface: `SailConnection`
      Returns the set of all unique context identifiers that are used to store statements.
      Specified by:
        `getContextIDs` in interface `SailConnection`
      Returns:
        An iterator over the context identifiers, should not contain any duplicates.
      Throws:
        `SailException`

    - #### getStatements

          public CloseableIteration<? extends Statement,SailException> getStatements(Resource subj,
                                                                                     IRI pred,
                                                                                     Value obj,
                                                                                     boolean includeInferred,
                                                                                     Resource... contexts)
                                                                              throws SailException

      Description copied from interface: `SailConnection`
      Gets all statements from the specified contexts that have a specific subject, predicate and/or object. All three parameters may be null to indicate wildcards. The `includeInferred` parameter can be used to control which statements are fetched: all statements or only the statements that have been added explicitly.
      Specified by:
        `getStatements` in interface `SailConnection`
      Parameters:
        `subj` - A Resource specifying the subject, or `null` for a wildcard.
        `pred` - A URI specifying the predicate, or `null` for a wildcard.
        `obj` - A Value specifying the object, or `null` for a wildcard.
        `includeInferred` - if false, no inferred statements are returned; if true, inferred statements are returned if available
        `contexts` - The context(s) to get the data from. Note that this parameter is a vararg and as such is optional. If no contexts are specified the method operates on the entire repository. A `null` value can be used to match context-less statements.
      Returns:
        The statements matching the specified pattern.
      Throws:
        `SailException` - If the Sail object encountered an error or unexpected situation internally.

    - #### hasStatement

          public boolean hasStatement(Resource subj,
                                      IRI pred,
                                      Value obj,
                                      boolean includeInferred,
                                      Resource... contexts)
                               throws SailException

      Description copied from interface: `SailConnection`
      Determines if the store contains any statements from the specified contexts that have a specific subject, predicate and/or object. All three parameters may be null to indicate wildcards. The `includeInferred` parameter can be used to control which statements are checked: all statements or only the statements that have been added explicitly.
      Specified by:
        `hasStatement` in interface `SailConnection`
      Parameters:
        `subj` - A Resource specifying the subject, or `null` for a wildcard.
        `pred` - An IRI specifying the predicate, or `null` for a wildcard.
        `obj` - A Value specifying the object, or `null` for a wildcard.
        `includeInferred` - if false, no inferred statements are returned; if true, inferred statements are returned if available
        `contexts` - The context(s) to get the data from. Note that this parameter is a vararg and as such is optional. If no contexts are specified the method operates on the entire repository. A `null` value can be used to match context-less statements.
      Returns:
        `true` iff the store contains any statements matching the supplied criteria, `false` otherwise.
      Throws:
        `SailException` - If the Sail object encountered an error or unexpected situation internally.

    - #### size

          public long size(Resource... contexts)
                    throws SailException

      Description copied from interface: `SailConnection`
      Returns the number of (explicit) statements in the store, or in specific contexts.
      Specified by:
        `size` in interface `SailConnection`
      Parameters:
        `contexts` - The context(s) to determine the size of. Note that this parameter is a vararg and as such is optional. If no contexts are specified the method operates on the entire repository. A `null` value can be used to match context-less statements.
      Returns:
        The number of explicit statements in this store, or in the specified context(s).
      Throws:
        `SailException`

    - #### size

          public long size(Resource context)
                    throws SailException

      Throws:
        `SailException`

    - #### commit

          public void commit()
                      throws SailException

      Description copied from interface: `SailConnection`
      Commits any updates that have been performed since the last time `SailConnection.commit()` or `SailConnection.rollback()` was called.
      Specified by:
        `commit` in interface `SailConnection`
      Throws:
        `UnknownSailTransactionStateException` - If the transaction state can not be determined (this can happen for instance when communication between client and server fails or times-out). It does not indicate a problem with the integrity of the store.
        `SailException` - If the SailConnection could not be committed.

    - #### rollback

          public void rollback()
                        throws SailException

      Description copied from interface: `SailConnection`
      Rolls back the transaction, discarding any uncommitted changes that have been made in this SailConnection.
      Specified by:
        `rollback` in interface `SailConnection`
      Throws:
        `UnknownSailTransactionStateException` - If the transaction state can not be determined (this can happen for instance when communication between client and server fails or times-out). It does not indicate a problem with the integrity of the store.
        `SailException` - If the SailConnection could not be rolled back.

    - #### addStatement

          public void addStatement(Resource subj,
                                   IRI pred,
                                   Value obj,
                                   Resource... contexts)
                            throws SailException

      Description copied from interface: `SailConnection`
      Adds a statement to the store.
      Specified by:
        `addStatement` in interface `SailConnection`
      Parameters:
        `subj` - The subject of the statement to add.
        `pred` - The predicate of the statement to add.
        `obj` - The object of the statement to add.
        `contexts` - The context(s) to add the statement to. Note that this parameter is a vararg and as such is optional. If no contexts are specified, a context-less statement will be added.
      Throws:
        `SailException` - If the statement could not be added, for example because no transaction is active.

    - #### removeStatements

          public void removeStatements(Resource subj,
                                       IRI pred,
                                       Value obj,
                                       Resource... contexts)
                                throws SailException

      Description copied from interface: `SailConnection`
      Removes all statements matching the specified subject, predicate and object from the repository. All three parameters may be null to indicate wildcards.
      Specified by:
        `removeStatements` in interface `SailConnection`
      Parameters:
        `subj` - The subject of the statement that should be removed, or `null` to indicate a wildcard.
        `pred` - The predicate of the statement that should be removed, or `null` to indicate a wildcard.
        `obj` - The object of the statement that should be removed , or `null` to indicate a wildcard. *
        `contexts` - The context(s) from which to remove the statement. Note that this parameter is a vararg and as such is optional. If no contexts are specified the method operates on the entire repository. A `null` value can be used to match context-less statements.
      Throws:
        `SailException` - If the statement could not be removed, for example because no transaction is active.

    - #### startUpdate

          public void startUpdate(UpdateContext modify)
                           throws SailException

      Description copied from interface: `SailConnection`
      Signals the start of an update operation. The given `op` maybe passed to subsequent `SailConnection.addStatement(UpdateContext, Resource, IRI, Value, Resource...)` or `SailConnection.removeStatement(UpdateContext, Resource, IRI, Value, Resource...)` calls before `SailConnection.endUpdate(UpdateContext)` is called.
      Specified by:
        `startUpdate` in interface `SailConnection`
      Throws:
        `SailException`

    - #### addStatement

          public void addStatement(UpdateContext modify,
                                   Resource subj,
                                   IRI pred,
                                   Value obj,
                                   Resource... contexts)
                            throws SailException

      Description copied from interface: `SailConnection`
      Adds a statement to the store. Called when adding statements through a `UpdateExpr` operation.
      Specified by:
        `addStatement` in interface `SailConnection`
      Parameters:
        `modify` - operation properties of the `UpdateExpr` operation producing these statements.
        `subj` - The subject of the statement to add.
        `pred` - The predicate of the statement to add.
        `obj` - The object of the statement to add.
        `contexts` - The context(s) to add the statement to. Note that this parameter is a vararg and as such is optional. If no contexts are specified, a context-less statement will be added.
      Throws:
        `SailException` - If the statement could not be added, for example because no transaction is active.

    - #### removeStatement

          public void removeStatement(UpdateContext modify,
                                      Resource subj,
                                      IRI pred,
                                      Value obj,
                                      Resource... contexts)
                               throws SailException

      Description copied from interface: `SailConnection`
      Removes all statements matching the specified subject, predicate and object from the repository. All three parameters may be null to indicate wildcards. Called when removing statements through a `UpdateExpr` operation.
      Specified by:
        `removeStatement` in interface `SailConnection`
      Parameters:
        `modify` - operation properties of the `UpdateExpr` operation removing these statements.
        `subj` - The subject of the statement that should be removed.
        `pred` - The predicate of the statement that should be removed.
        `obj` - The object of the statement that should be removed.
        `contexts` - The context(s) from which to remove the statement. Note that this parameter is a vararg and as such is optional. If no contexts are specified the method operates on the entire repository. A `null` value can be used to match context-less statements.
      Throws:
        `SailException` - If the statement could not be removed, for example because no transaction is active.

    - #### endUpdate

          public void endUpdate(UpdateContext modify)
                         throws SailException

      Description copied from interface: `SailConnection`
      Indicates that the given `op` will not be used in any call again. Implementations should use this to flush of any temporary operation states that may have occurred.
      Specified by:
        `endUpdate` in interface `SailConnection`
      Throws:
        `SailException`

    - #### clear

          public void clear(Resource... contexts)
                     throws SailException

      Description copied from interface: `SailConnection`
      Removes all statements from the specified/all contexts. If no contexts are specified the method operates on the entire repository.
      Specified by:
        `clear` in interface `SailConnection`
      Parameters:
        `contexts` - The context(s) from which to remove the statements. Note that this parameter is a vararg and as such is optional. If no contexts are specified the method operates on the entire repository. A `null` value can be used to match context-less statements.
      Throws:
        `SailException` - If the statements could not be removed.

    - #### getNamespaces

          public CloseableIteration<? extends Namespace,SailException> getNamespaces()
                                                                              throws SailException

      Description copied from interface: `SailConnection`
      Gets the namespaces relevant to the data contained in this Sail object.
      Specified by:
        `getNamespaces` in interface `SailConnection`
      Returns:
        An iterator over the relevant namespaces, should not contain any duplicates.
      Throws:
        `SailException` - If the Sail object encountered an error or unexpected situation internally.

    - #### getNamespace

          public String getNamespace(String prefix)
                              throws SailException

      Description copied from interface: `SailConnection`
      Gets the namespace that is associated with the specified prefix, if any.
      Specified by:
        `getNamespace` in interface `SailConnection`
      Parameters:
        `prefix` - A namespace prefix, or an empty string in case of the default namespace.
      Returns:
        The namespace name that is associated with the specified prefix, or `null` if there is no such namespace.
      Throws:
        `SailException` - If the Sail object encountered an error or unexpected situation internally.

    - #### setNamespace

          public void setNamespace(String prefix,
                                   String name)
                            throws SailException

      Description copied from interface: `SailConnection`
      Sets the prefix for a namespace.
      Specified by:
        `setNamespace` in interface `SailConnection`
      Parameters:
        `prefix` - The new prefix, or an empty string in case of the default namespace.
        `name` - The namespace name that the prefix maps to.
      Throws:
        `SailException` - If the Sail object encountered an error or unexpected situation internally.

    - #### removeNamespace

          public void removeNamespace(String prefix)
                               throws SailException

      Description copied from interface: `SailConnection`
      Removes a namespace declaration by removing the association between a prefix and a namespace name.
      Specified by:
        `removeNamespace` in interface `SailConnection`
      Parameters:
        `prefix` - The namespace prefix, or an empty string in case of the default namespace.
      Throws:
        `SailException` - If the Sail object encountered an error or unexpected situation internally.

    - #### clearNamespaces

          public void clearNamespaces()
                               throws SailException

      Description copied from interface: `SailConnection`
      Removes all namespace declarations from the repository.
      Specified by:
        `clearNamespaces` in interface `SailConnection`
      Throws:
        `SailException` - If the Sail object encountered an error or unexpected situation internally.

    - #### pendingRemovals

          public boolean pendingRemovals()

      Description copied from interface: `SailConnection`
      Indicates if the Sail has any statement removal operations pending (not yet `flushed`) for the current transaction.
      Specified by:
        `pendingRemovals` in interface `SailConnection`
      Returns:
        true if any statement removal operations have not yet been flushed, false otherwise.
      See Also:
        `SailConnection.flush()`

    - #### explain

          public Explanation explain(Explanation.Level level,
                                     TupleExpr tupleExpr,
                                     Dataset dataset,
                                     BindingSet bindings,
                                     boolean includeInferred,
                                     int timeoutSeconds)

      Description copied from interface: `SailConnection`

      Explain how the TupleExpr will be (or has been) executed/evaluated by returning a TupleExpr (which may or may not be the provided TupleExpr) that has gone through zero or more of the stages prior to and also including execution as specified by the provided level.

      This method is used by the Query interface.

      WARNING: This method is experimental and is subject to change or removal without warning. There is currently only partial support for this method in RDF4J and and UnsupportedOperationException where support is lacking.

      Specified by:
        `explain` in interface `SailConnection`
      Parameters:
        `level` - the explanation level, eg. OPTIMIZED
        `tupleExpr` - The tuple expression to evaluate. Mutable.
        `dataset` - The dataset to use for evaluating the query, `null` to use the Sail's default dataset.
        `bindings` - A set of input parameters for the query evaluation. The keys reference variable names that should be bound to the value they map to.
        `includeInferred` - Indicates whether inferred triples are to be considered in the query result. If false, no inferred statements are returned; if true, inferred statements are returned if available
        `timeoutSeconds` - for explanations that require execution a timeout can be provided in seconds
      Returns:
        The resulting tuple expression after being run through the specified level

    - #### begin

          public void begin()
                     throws SailException

      Description copied from interface: `SailConnection`
      Begins a transaction requiring `SailConnection.commit()` or `SailConnection.rollback()` to be called to close the transaction. The transaction will use the default `IsolationLevel` level for the SAIL, as returned by `Sail.getDefaultIsolationLevel()`.
      Specified by:
        `begin` in interface `SailConnection`
      Throws:
        `SailException` - If the connection could not start a transaction or if a transaction is already active on this connection.

    - #### begin

          public void begin(IsolationLevel level)
                     throws SailException

      Description copied from interface: `SailConnection`
      Begins a transaction with the specified `IsolationLevel` level, requiring `SailConnection.commit()` or `SailConnection.rollback()` to be called to close the transaction.
      Specified by:
        `begin` in interface `SailConnection`
      Parameters:
        `level` - the transaction isolation level on which this transaction operates.
      Throws:
        `UnknownSailTransactionStateException` - If the IsolationLevel is not supported by this implementation
        `SailException` - If the connection could not start a transaction, if the supplied transaction isolation level is not supported, or if a transaction is already active on this connection.

    - #### setTransactionSettings

          public void setTransactionSettings(TransactionSetting... settings)

      Description copied from interface: `SailConnection`
      Pass any transaction-specific settings to the SailConnection. This method needs to be called before the transaction is `started` .

      Sail implementations can override this method to receive the transaction settings (to inspect and/or pass them along to any wrapped sail objects). Remember to call `super.setTransactionSettings(settings)` if you override this method.

      Specified by:
        `setTransactionSettings` in interface `SailConnection`
      Parameters:
        `settings` - the transaction settings on which the next transaction operates. It may or may not contain the isolation level.

    - #### flush

          public void flush()
                     throws SailException

      Description copied from interface: `SailConnection`
      Flushes any pending updates and notify changes to listeners as appropriate. This is an optional call; calling or not calling this method should have no effect on the outcome of other calls. This method exists to give the caller more control over the efficiency when calling `SailConnection.prepare()`. This method may be called multiple times within the same transaction.
      Specified by:
        `flush` in interface `SailConnection`
      Throws:
        `SailException` - If the updates could not be processed, for example because no transaction is active.

    - #### prepare

          public void prepare()
                       throws SailException

      Description copied from interface: `SailConnection`
      Checks for an error state in the active transaction that would force the transaction to be rolled back. This is an optional call; calling or not calling this method should have no effect on the outcome of `SailConnection.commit()` or `SailConnection.rollback()`. A call to this method must be followed by (in the same thread) with a call to `SailConnection.prepare()` , `SailConnection.commit()`, `SailConnection.rollback()`, or `SailConnection.close()` . This method may be called multiple times within the same transaction by the same thread. If this method returns normally, the caller can reasonably expect that a subsequent call to `SailConnection.commit()` will also return normally. If this method returns with an exception the caller should treat the exception as if it came from a call to `SailConnection.commit()`.
      Specified by:
        `prepare` in interface `SailConnection`
      Throws:
        `UnknownSailTransactionStateException` - If the transaction state can not be determined (this can happen for instance when communication between client and server fails or times-out). It does not indicate a problem with the integrity of the store.
        `SailException` - If there is an active transaction and it cannot be committed.

    - #### isActive

          public boolean isActive()
                           throws UnknownSailTransactionStateException

      Description copied from interface: `SailConnection`
      Indicates if a transaction is currently active on the connection. A transaction is active if `SailConnection.begin()` has been called, and becomes inactive after `SailConnection.commit()` or `SailConnection.rollback()` has been called.
      Specified by:
        `isActive` in interface `SailConnection`
      Returns:
        `true` iff a transaction is active, `false` iff no transaction is active.
      Throws:
        `UnknownSailTransactionStateException` - if the transaction state can not be determined (this can happen for instance when communication between client and server fails or times out).

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