To solve such problem, the most clean way is to create an entirely different XML namespace to separate old commands and new commands, although they look pretty much alike in everyway. In WSDL, if specification 1.0 defines some XML element to be "mandatory", then it cannot be later changed to "optional" in 2.0, because doing so will violate the principle of backward compatibility. As to the real cause about why make such potentially incompatible XML namespace changes, we think it's because ONVIF is very prudent about specification definition. Other parts of ONVIF specification such as Media service do not suffer from similar issues because XML namespace is not changed. This changed XML namespace makes 1.0 and 2.0 two sets of entirely different commands. Among the changes, I/O related commands are moved to Device IO XML namespace in 2.0, while they are in Device Management during 1.0.
There are some structural changes of Device Management service during the transition from 1.0 to 2.0.This makes PTZ service 1.0 and 2.0 two sets of entirely different commands.
The XML namespace of the PTZ service has changed during the transition from 1.0 to 2.0.This makes Imaging service 1.0 and 2.0 two sets of entirely different commands. The XML namespace of the Imaging service has changed during the transition from 1.0 to 2.0.The commonly referred incompatibility issues among version 1.0, 1.1, 1.2, and 2.0 can be summarized to the following issues: The design principle of ONVIF is "backward compatible". What does ONVIF version 1.0, 1.1, 1.2, 2.0 generally means? Why version 1.0, 1.1, 1.2, 2.0 can be incompatible?
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