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In .Net, value-typed variables are not allowed to have null values, but chances are you would need to assign null values to such variables in your code, although it is not sensible to do so (why on earth would you want an integer to be null in the first place? It would have corrupted your program at some point of execution).

One example where we need nullable type is when we use strongly-typed DataSets. When we associate a stored procedure (or a Sql command text) to the TableAdapter that comes with the DataSet, the input parameter may somehow need to be null.

The workaround we had last time (in .Net 1.1 or earlier) was to set such input parameter to either empty string or -1.

Now, in .Net 2.0, the nullable type has been introduced and all value-typed objects can be assigned to a nullable type by simply:

Nullable<int> iSomeValue = null;

or

?int iSomeValue = null;


This worked perfectly fine, till Remoting kicks in.

Nullable types are not supported in the SOAP serializer, and thus could not be passed as a parameter through the Remoting interface!

Well, looks like we can only use nullable types within the data access layer, and continue to use value types across the Remoting interface.

Here is the confirmation where nullable types are not SOAP serializer-supported:
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=147645&SiteID=1