com.denodo.vdb.engine.customwrapper

Interface CustomWrapper

All Known Implementing Classes:

AbstractCustomWrapper

public interface CustomWrapper

All VDP Custom Wrappers must implement this interface. A default implementation is provided (AbstractCustomWrapper). For convenience, the user is encouraged to extend AbstractCustomWrapper instead of implementing CustomWrapper directly.

Method Summary

Modifier and Type	Method and Description
void	commit() Defines how this Custom Wrappers performs a commit operation in its data source in the context of a distributed transaction.
int	delete(CustomWrapperConditionHolder condition, Map<String,String> inputValues) Defines how this Custom Wrapper deletes data from the data source.
CustomWrapperConfiguration	getConfiguration() Defines this Custom Wrapper's configuration based on several configurable properties provided by the CustomWrapperConfiguration class.
CustomWrapperInputParameter[]	getDataSourceInputParameters() Defines what input parameters supports the Data Source associated to the wrapper.
CustomWrapperInputParameter[]	getInputParameters() Defines what input parameters supports this Custom Wrapper.
CustomWrapperSchemaParameter[]	getSchemaParameters(Map<String,String> inputValues) Defines the schema of this Custom Wrapper.
int	insert(Map<CustomWrapperFieldExpression,Object> insertValues, Map<String,String> inputValues) Defines how this Custom Wrapper inserts values into the data source.
void	prepare() Defines how this Custom Wrapper performs a prepare operation in its data source in the context of a distributed transaction.
void	rollback() Defines how this Custom Wrapper performs a rollback operation in its data source in the context of a distributed transaction.
void	run(CustomWrapperConditionHolder condition, List<CustomWrapperFieldExpression> projectedFields, CustomWrapperResult result, Map<String,String> inputValues) Defines how this Custom Wrapper acts when being queried.
boolean	stop() Stops the execution of this Custom Wrapper.
int	update(Map<CustomWrapperFieldExpression,Object> updateValues, CustomWrapperConditionHolder condition, Map<String,String> inputValues) Defines how this Custom Wrapper updates data in the data source.

Method Detail

getDataSourceInputParameters

CustomWrapperInputParameter[] getDataSourceInputParameters()

Defines what input parameters supports the Data Source associated to the wrapper.

Returns:

an array of CustomWrapperInputParameter

See Also:

CustomWrapperInputParameter

getInputParameters

CustomWrapperInputParameter[] getInputParameters()

Defines what input parameters supports this Custom Wrapper.

Returns:

an array of CustomWrapperInputParameter

See Also:

CustomWrapperInputParameter

getSchemaParameters

CustomWrapperSchemaParameter[] getSchemaParameters(Map<String,String> inputValues)
                                            throws CustomWrapperException

Defines the schema of this Custom Wrapper.

Parameters:

inputValues - a Map<String, String> which associates this Custom Wrapper's input parameters' names (as defined in getInputParameters()) with their current values.

Returns:

an array of CustomWrapperSchemaParameter that defines the schema of this Custom Wrapper.

Throws:

CustomWrapperException - Throw this exception if there is any error during the process of obtaining the schema of the wrapper based on these parameters. The execution engine will capture this exception and will interrupt the execution of this custom wrapper, interrupt the query and return the error message of this exception to the client application.

See Also:

CustomWrapperSchemaParameter

run

void run(CustomWrapperConditionHolder condition,
         List<CustomWrapperFieldExpression> projectedFields,
         CustomWrapperResult result,
         Map<String,String> inputValues)
  throws CustomWrapperException

Defines how this Custom Wrapper acts when being queried. Typically, this will involve analyzing the passed condition and inputValues, constructing a query taking into account the passed projectedFields, retrieving data from this Custom Wrapper data source and finally inserting such data in the passed result object.

Parameters:

condition - the query's condition (akin to the WHERE clause in a SQL query).

projectedFields - the query's projected fields (akin to the SELECT clause in a SQL query).

result - an object which receives the data retrieved by this Custom Wrapper.

inputValues - a Map<String, String> which associates this Custom Wrapper's input parameters' names (as defined in getInputParameters()) with their current values.

Throws:

CustomWrapperException - Throw this exception if there is an error during the execution of this wrapper. The execution engine will capture this exception and will interrupt the execution of this custom wrapper, interrupt the query and return the error message of this exception to the client application.

See Also:

CustomWrapperConditionHolder, CustomWrapperFieldExpression, CustomWrapperResult

stop

boolean stop()

Stops the execution of this Custom Wrapper.

Returns:

true if this Custom Wrapper can stop its execution, false otherwise.

insert

int insert(Map<CustomWrapperFieldExpression,Object> insertValues,
           Map<String,String> inputValues)
    throws CustomWrapperException

Defines how this Custom Wrapper inserts values into the data source. Typically, this will involve analyzing the passed insertValues and then accessing the data source to perform the required insertion.

Parameters:

insertValues - a Map<CustomWrapperFieldExpression, Object> which associates fields with values, in similar fashion to the INSERT statement in SQL.

inputValues - a Map<String, String> which associates this Custom Wrapper's input parameters' names (as defined in getInputParameters()) with their current values.

Returns:

the number of successfully inserted values.

Throws:

CustomWrapperException - Throw this exception from your code if there is an error inserting a row in the underlying data source. The execution engine will capture this exception and will interrupt the execution of this custom wrapper, interrupt the query and return the error message of this exception to the client application.

See Also:

CustomWrapperFieldExpression

delete

int delete(CustomWrapperConditionHolder condition,
           Map<String,String> inputValues)
    throws CustomWrapperException

Defines how this Custom Wrapper deletes data from the data source. Typically, this will involve analyzing the passed condition and then accessing the data source to perform the required deletions.

Parameters:

condition - the deletion condition (akin to the WHERE clause in a SQL DELETE statement).

inputValues - a Map<String, String> which associates this Custom Wrapper's input parameters' names (as defined in getInputParameters()) with their current values.

Returns:

the number of successfully deleted values.

Throws:

CustomWrapperException - Throw this exception from your code if there is an error deleting a row in the underlying data source. The execution engine will capture this exception and will interrupt the execution of this custom wrapper, interrupt the query and return the error message of this exception to the client application.

See Also:

CustomWrapperConditionHolder

update

int update(Map<CustomWrapperFieldExpression,Object> updateValues,
           CustomWrapperConditionHolder condition,
           Map<String,String> inputValues)
    throws CustomWrapperException

Defines how this Custom Wrapper updates data in the data source. Typically, this will involve analyzing the passed updateValues and condition, and then accessing the data source to perform the required updates.

Parameters:

updateValues - a Map<CustomWrapperFieldExpression, Object> which associates fields with values, in similar fashion to the UPDATE statement in SQL. The value can be a literal expressed as a Java object or a field expressed as a CustomWrapperFieldExpression

condition - the insert condition (akin to the WHERE clause in a SQL UPDATE statement).

inputValues - a Map<String, String> which associates this Custom Wrapper's input parameters' names (as defined in getInputParameters()) with their current values.

Returns:

the number of successfully updated values.

Throws:

CustomWrapperException - Throw this exception if there is an error updating a row in the underlying data source. The execution engine will capture this exception and will interrupt the execution of this custom wrapper, interrupt the query and return the error message of this exception to the client application.

See Also:

CustomWrapperFieldExpression, CustomWrapperConditionHolder

commit

void commit()

Defines how this Custom Wrappers performs a commit operation in its data source in the context of a distributed transaction.

rollback

void rollback()

Defines how this Custom Wrapper performs a rollback operation in its data source in the context of a distributed transaction.

prepare

void prepare()

Defines how this Custom Wrapper performs a prepare operation in its data source in the context of a distributed transaction.

getConfiguration

CustomWrapperConfiguration getConfiguration()

Defines this Custom Wrapper's configuration based on several configurable properties provided by the CustomWrapperConfiguration class.

Returns:

a CustomWrapperConfiguration instance defining this Custom Wrapper configuration parameters.