Workflow is a key technology for eScience. It enables scientific tools to be composed and the resulting workflows to be managed. Workflow and most other computing tools typically distinguish batch from interactive operation. This distinction is ill-suited to scientific experimentation which typically starts interactively and then may progress to batch operation for larger or repeated runs of experiments. In this paper we present a scientific workflow model which unifies batch and interactive operation. This supports seamless experimentation by scientists. The model is implemented in a web based environment through the Microsoft Windows Workflow system and features a novel model for workflow components.