io.cdap.wrangler.api

Interface Executor<I,O>

Type Parameters:

I - type of input object

O - type of output object

All Superinterfaces:

Serializable

All Known Subinterfaces:

Directive

@PublicEvolving
public interface Executor<I,O>
extends Serializable

A interface defining the wrangle Executor in the wrangling RecipePipeline.

Method Summary

Modifier and Type	Method and Description
void	destroy() This method provides a way for the directive to de-initialize or destroy the resources that were acquired during the initialization phase.
O	execute(I rows, ExecutorContext context) Executes a wrangle step on single Row and return an array of wrangled Row.
void	initialize(Arguments args) This method provides a way for the custom directive writer the ability to access the arguments passed by the users.

Method Detail

initialize

void initialize(Arguments args)
         throws DirectiveParseException

This method provides a way for the custom directive writer the ability to access the arguments passed by the users.

This method is invoked only once during the initialization phase of the Executor object. The arguments are constructed based on the definition as provided by the user in the method above define.

Following is an example of how initialize could be used to accept the arguments that are tokenized and parsed by the framework. public void initialize(Arguments args) throws DirectiveParseException { ColumnName column = args.value("column"); if (args.contains("number") { Numeric number = args.value("number"); } Text text = args.value("text"); Bool bool = args.value("boolean"); Expression expression = args.value("expression"); }

Parameters:

args - Tokenized and parsed arguments.

Throws:

DirectiveParseException - thrown by the user in case of any issues with validation or ensuring the argument values are as expected.

execute

O execute(I rows,
          ExecutorContext context)
   throws DirectiveExecutionException,
          ErrorRowException,
          ReportErrorAndProceed

Executes a wrangle step on single Row and return an array of wrangled Row.

Parameters:

rows - List of input Row to be wrangled by this step.

context - ExecutorContext passed to each step.

Returns:

Wrangled List of Row.

Throws:

DirectiveExecutionException

ErrorRowException

ReportErrorAndProceed

destroy

void destroy()

This method provides a way for the directive to de-initialize or destroy the resources that were acquired during the initialization phase. This method is called from the Transform#destroy() when the directive is invoked within a plugin or when during Service#destroy() when invoked in the service. This method is specifically designed not to thrown any exceptions. So, if the the user code is throws any exception, the system will be unable to react or correct at this phase of invocation.