Wrapping activity inputs and outputs

The implementation of the Workflow Runtime uses mechanisms to internally stay agnostic of used APIs. To achieve this, all non-builtin types in the output of an activity should get wrapped in a WrapperBase:

public Task<IDictionary<string, object>> Execute(IDictionary<string, object> inputs, IActivityContext context)
{
    // activity work, e.g. creating a feature

    IDictionary<string, object> outputs = new Dictionary<string, object>();

    outputs.Add("feature", new CustomActivityWrapper(createdFeature));

    return Task.FromResult(outputs);
}

where an implementation of a WrapperBase at least offers a Unwrap method:

private class CustomActivityWrapper : WrapperBase
{
    //internals of the wrapper

    public override object Unwrap()
    {
        return _actualObject;
    }
}

Unwrapping inputs

Thus all inputs in an activity should get unwrapped before working with it. On Studio Desktop you may cast the input either to WrapperBase or IServiceProvider - both methods are equivalent:

public Task<IDictionary<string, object>> Execute(IDictionary<string, object> inputs, IActivityContext context)
{
   // Variant 1 IServiceProvider:
   IServiceProvider provider = inputs["feature"] as IServiceProvider;
   Row actualObject = (Row)provider.GetService(typeof(Row));

   // Variant 2 WrapperBase:
   WrapperBase wrapper = inputs["feature"] as WrapperBase;
   Row actualObject2 = (Row)wrapper.Unwrap();
}