Microsoft® Windows® Workflow Foundation Step by Step

Creating and Using Custom External Data Service Activities

Looking back, we just wrote more code than we’ve written in the entire book so far. The reason for this is WF can’t know beforehand what information our workflows will trade with our host applications, so some work is clearly necessary to fill in that gap.

However, WF knows all about workflow activities, and happily there is a tool we can use to interpret our data-transfer interface, marked with the ExternalDataExchange attribute, and automatically generate WF activities.

The application we’re building in this chapter sends data from the workflow to the host application, which is to say the data transfer is unidirectional. I did this intentionally because there is more to learn before we ...