Class SourceBase<TDerived, TOutput, TError>

An abstract dataflow worker with one Output port and one ErrorOutput port, which can be used to create a dataflow source.

When starting a worker, the library calls RunAsync() during the worker Running phase. A derived class must override this abstract method, and call methods on the Output and ErrorOutput ports to pass data rows to the downstream worker.

Note that the worker Running phase also includes additional places where logic can optionally be inserted via callbacks, to e.g. customize the initialization, cleanup, and error handling of existing workers. This is mostly used when customizing workers that are not designed to be derived from (i.e. without a "Base" suffix). See Worker Life-cycle for details.

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

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

The type of the derived worker. Class definition example:

public class MySource<TOutput,TError>
    : SourceBase<MySource<TOutput,TError>,TOutput,TError>
    where TOutput : class, new()
    where TError : class
{ 
    // ...
}
TOutput

The type of each Output row.
TError

The type of each ErrorOutput row.

Constructors

SourceBase(WorkerParent, String, Func<Boolean>)

Initializes a new instance of the SourceBase<TDerived, TOutput, TError> abstract dataflow worker, with one Output port and one ErrorOutput port. It can be used to create a dataflow source.

Declaration
protected SourceBase(WorkerParent workerParent, string workerName, Func<bool> isStartableFunc)
Parameters
Type Name Description
WorkerParent workerParent

The parent worker or worker system that the new child worker will be added to. Cannot be null.
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 "__".

Func<Boolean> isStartableFunc

Function to calculate the worker start constraint; it should return true for startable and false for not startable. Defaults to startable if null.
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>

Output

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

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

Implements