"C:\Program Files\Microsoft.NET\SDK\v1.1\Bin\wsdl" /l:Borland.Delphi.DelphiCodeProvider, DelphiProvider, Version=9.0.1761.24408, Culture=neutral, PublicKeyToken=91d62ebb5b0d1b1b http://webservices.amazon.com/AWSECommerceService/ AWSECommerceService.wsdl
Microsoft requires the complete "stuff" to be provided so that the wsdl executable can locate the code provider to load.
In 2017, with the release of Delphi 10.2 Tokyo, Embarcadero introduced a specialized implementation of the Observer pattern into the System.Classes unit. While it has been in the wild for 9 years, it remains a "hidden" architecture for many, primarily because it serves as the invisible engine behind LiveBindings. Other than live bindings, you can also use the Observer pattern as a way to update component settings to the Windows registry, an .ini file, or persist it elsewhere.
System.Classes