Class RowsTargetBase<TDerived, TInput, TError>

An abstract dataflow worker which repeatedly executes the OnInputRowsAsync() method when there are input rows available on the Input port. The library user must inherit this class and override OnInputRowsAsync to provide custom functionality. It also has an ErrorOutput port.

This class allows the developer to write synchronous or asynchronous code as needed, without having to check for availability of input rows (which simplifies the implementation), as long as more no rows than are available are taken (typically by taking multiple rows at a time, e.g. via TakeBufferAsync(TInput[])).

The derived class can additionally override RunAsync() to add logic that runs before and after all processing of rows, in which case the base class base.RunAsync() must be called. The derived class (or its user) can also use worker callbacks to add logic.

Use RowsTargetBase<TDerived, TInput> instead if an ErrorOutput port is not needed. Also see the RowsTargetBase example.

Note: The input port uses the Default policy. Consider whether this is appropriate, or should be changed, see BufferingMode for further details.

Inheritance
Object
WorkerParent
WorkerBase
WorkerBase<TDerived>
RowsTargetBase<TDerived, TInput>
RowsTargetBase<TDerived, TInput, TError>
Implements
Inherited Members
Namespace: actionETL
Assembly: actionETL.dll
Syntax
public abstract class RowsTargetBase<TDerived, TInput, TError> : RowsTargetBase<TDerived, TInput>, IDisposeOnFinished where TDerived : RowsTargetBase<TDerived, TInput, TError> where TInput : class where TError : class
Type Parameters
Name Description
TDerived

The type of the derived worker. Class definition example:

public class MyTarget<TInput,TError>
    : RowsTargetBase<MyTarget<TInput,TError>,TInput,TError>
    where TInput : class
    where TError : class
{ 
    // ...
}
TInput

The type of each Input row.
TError

The type of each ErrorOutput row, often the same type as TInput.

Constructors

RowsTargetBase(in DownstreamFactory<TInput>, String)

Initializes a new instance of the RowsTargetBase<TDerived, TInput, TError> abstract dataflow worker, which repeatedly executes the OnInputRowsAsync method when there are input rows available on the Input port.

Declaration
protected RowsTargetBase(in DownstreamFactory<TInput> downstreamFactory, string workerName)
Parameters
Type Name Description
DownstreamFactory<TInput> downstreamFactory

The downstream factory, which specifies the parent worker and (optionally) the upstream port to link the "first" input port of this dataflow worker to.

Get it from Link when the upstream port is known ahead of time (which is usually the case). Otherwise get it from GetDownstreamFactory<TInput>(), and link the transform or target explicitly using LinkTo(InputPort<TOutput>) or LinkFrom(OutputPortBase<TInput>).

String workerName

Name of the worker.

Set to a prefix plus a trailing "/" (e.g. "MyPrefix-/") to generate a unique name from the prefix plus an increasing number starting at 1.

While less useful, set to null, whitespace or "/" to generate a unique name from the worker type plus an increasing number starting at 1.

The name cannot otherwise contain "/", and cannot start with double underscore "__".

Exceptions
Type Condition
ArgumentException

workerName:

  • Workers with the same parent must have unique names.
  • Worker and worker system names cannot contain '/' or start with double underscore '__'.
ArgumentNullException

workerParent - All workers must have a parent. The top level workers have the worker system as parent.
InvalidOperationException
  • Cannot add child worker to parent which has completed. Are you adding it to the correct parent?
  • Cannot add worker to parent, since its children have been started. Are you adding it to the correct parent?

Properties

ErrorOutput

Gets the error output port for sending error rows to logging and an optional downstream worker.

Declaration
public ErrorOutputPort<TError> ErrorOutput { get; }
Property Value
Type Description
ErrorOutputPort<TError>

Implements