NewDataForward creates a source data forwarder.

WithCallbackUploader sets the callback uploader for the vertex.

WithLogger is used to return logger information.

WithReadBatchSize sets the read batch size.

WithRetryInterval sets the retry interval.

WithTransformer sets the transformer to be applied.

WithTransformerConcurrency sets concurrency for source transformer processing.

DataForward reads data from source and forwards to inter-step buffers.

Shutdown tracks and enforces the shutdown activity.