Note: This question was asked at a time when C# did not yet support optional parameters (i.e. before C# 4).
We\'re building a web API tha
The typical way this is handled in C# as stephen mentioned is to overload the method. By creating multiple versions of the method with different parameters you effectively create optional parameters. In the forms with fewer parameters you would typically call the form of the method with all of the parameters setting your default values in the call to that method.