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Adding Custom Startup Parameters

Before we move on to a more interesting workflow example, allow me to address how to define

application-wide parameters. If you examine the signature of the designer-generated methods

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used by our Code activities (ShowInstructions() and NameNotValid() specifically), you may have

noticed that they are called via WF events that are making use of the System.EventHandler delegate

(given the incoming parameters of type object and System.EventArgs).

Because this .NET delegate demands the registered event handler and takes System.Object and

System.EventArgs as arguments, you may wonder how to pass in custom parameters to be used by a

Code activity. In fact, you may be wondering how to define custom arguments that can be used by

any activity within the current workflow instance.

As it turns out, the WF engine supports the use of custom parameters using a generic

Dictionary type. The name/value pairs added to the Dictionary object must then

be associated to (identically named) properties on your workflow instance. Once you’ve done this,

you can pass these arguments into the WF runtime engine when you start your workflow instance.

Using this approach, you are able to get and set custom parameters throughout a particular work-

flow instance.