The sample workflow is bound to a list named Customers. After the user enters a value for CustomerID, they can manually run the workflow. The workflow uses the CustomerID to search for the customer using the public Northwind sample OData service (http://services.odata.org/Northwind/Northwind.svc/).
When it finds the customer, it adds the details it retrieves from the service to the list item and then concludes. The part of the workflow that calls the web service and extracts the details from the response is contained within a custom activity.
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