Class TwoInputTransformBase<TDerived, TLeftInput, TRightInput, TOutput>

An abstract dataflow worker with two input ports and one Output port, which can be used to create a dataflow transform. The library user must inherit this class and override the RunAsync() method (which will get called once) to add custom functionality. This method should in turn call methods on the LeftInput and RightInput ports to consume rows from the upstream workers, and call methods on the Output port to send rows to the downstream worker.

Note that the two inputs by default provide Full buffering of incoming data, which potentially can consume a large amount of memory. Consider whether this is appropriate, or should be overridden, see BufferingMode for further details.

Note that all dataflow workers must adhere to the Row Ownership rules.

Consider using TransformBase<TDerived, TInput, TOutput> instead if two input ports are not needed. Also see the TransformBase example.

Inheritance
Object
WorkerParent
WorkerBase
WorkerBase<TDerived>
TwoInputTransformBase<TDerived, TLeftInput, TRightInput, TOutput>
Implements
Inherited Members
Namespace: actionETL
Assembly: actionETL.dll
Syntax
public abstract class TwoInputTransformBase<TDerived, TLeftInput, TRightInput, TOutput> : WorkerBase<TDerived>, IDisposeOnFinished where TDerived : TwoInputTransformBase<TDerived, TLeftInput, TRightInput, TOutput> where TLeftInput : class where TRightInput : class where TOutput : class
Type Parameters
Name Description
TDerived

The type of the derived worker. Class definition example:

public class MyTransform<TLeftInput,TRightInput,TOutput>
    : TwoInputTransformBase<MyTransform<TLeftInput,TRightInput,TOutput>,TLeftInput,TRightInput,TOutput>
    where TLeftInput : class
    where TRightInput : class
    where TOutput : class
{ 
    // ...
}
TLeftInput

The type of each LeftInput row.
TRightInput

The type of each RightInput row.
TOutput

The type of each Output row.
Remarks

Note: This class only has overloads for asynchronous callbacks, since using synchronous ones would require the callback to block a thread when there is no upstream rows or downstream demand available, which is not appropriate.

Constructors

TwoInputTransformBase(in DownstreamFactory<TLeftInput>, String, OutputPortBase<TRightInput>)

Initializes a new instance of the TwoInputTransformBase<TDerived, TLeftInput, TRightInput, TOutput> abstract dataflow worker. It executes an asynchronous action once, which consumes data from two upstream workers and sends data to one downstream worker.

Declaration
protected TwoInputTransformBase(in DownstreamFactory<TLeftInput> downstreamFactory, string workerName, OutputPortBase<TRightInput> rightInputFrom)
Parameters
Type Name Description
DownstreamFactory<TLeftInput> downstreamFactory

The downstream factory, which specifies the parent worker and (optionally) the upstream port to link the "first" LeftInput 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 "__".

OutputPortBase<TRightInput> rightInputFrom

The upstream output port to link the RightInput port to.
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

LeftInput

Gets the left input port for consuming rows from the left upstream worker.

Declaration
public InputPort<TLeftInput> LeftInput { get; }
Property Value
Type Description
InputPort<TLeftInput>

The left input port.

Output

Gets the output port for sending rows to the downstream worker.

Declaration
public OutputPort<TOutput> Output { get; }
Property Value
Type Description
OutputPort<TOutput>

The output port.

RightInput

Gets the right input port for consuming rows from the right upstream worker.

Declaration
public InputPort<TRightInput> RightInput { get; }
Property Value
Type Description
InputPort<TRightInput>

The right input port.

Implements