In the latest update 6.0.1.7+ outsystems improved web service reference, which now allows for nulliable datetime. (See below)
However it does not allow for nullable datetime for web service providers, that means
nulldate in a SOAP web service response will return
1900-01-01T00:00:00. rather than an empty element.
Please fix the web service provider null date time issue with the standard nulliable date behaviour (ie Have an option not to include the nulldate as 1900-01-01T00:00:00 but rather an empty element)
"XML Schema: Structures introduces a mechanism for signaling that an element should be accepted as ·valid· when it has no content despite a content type which does not require or even necessarily allow empty content. An element may be ·valid· without content if it has the attribute xsi:nil with the value true. An element so labeled must be empty, but can carry attributes if permitted by the corresponding complex type."
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Service Studio 6.0.1.7 (2011-11-19)
? What's new in 6.0.1.7
o Web Reference enhancements:
? Support for Null and Nillable parameters and attributes (#253956)
This can be seen in the image below
REF: http://www.outsystems.com/help/servicestudio/6.0/Designing_Actions/Input_Parameter_Properties.htm