Trigger Hikvision NVR Recording Via HTTP API?

Does anybody know if it's possible to trigger recording on a Hikvision NVR via an HTTP API?

I have reviewed and experimented with their published ISAPI HTTP API, but this only appears to support configuration of the NVR, not activation of triggers or start/stop recording.

The use case is as follows:

• Wireless PIR notifies an open source home automation app when triggered
• Home automation app can send any HTTP command when wireless PIR is triggered
• I want to have the wireless PIR trigger a channel on the Hikvision NVR to start recording when the PIR trips

I would expect to be able to perform a HTTP GET/PUT request with something like <nvr-ip>/Channels/1/record or <nvr-ip>/Triggers/1 to inject a trigger from a third party source.

I am used to integrating against PC-based NVR software (Milestone, Genetec, etc...) where this kind of function is commonplace. Maybe my expectations are too high for these little Hikvision boxes?

Thanks in advance for any insight.