UPnP Control (Windows Embedded CE 6.0)
1/6/2010
After a control point has learned of a device and its services, it can use these services to invoke actions and query for state variable values.
To invoke a specific action:
- A control point sends a POST control message containing SOAP-formatted content to the device's service. A control message contains vendor-specific information, action names, argument names, and variables that are defined by the UPnP Forum.
- The service replies with an HTTP response that notifies the control point of the status of the request. If the request can be completed within 30 seconds, including expected transmission time, the response contains the results of the request. If the request takes longer than 30 seconds, the device returns a response without complete data and later sends an event when the request is complete.
The control point can also query a device's service for state variables. The communication between control point and device in this case is the same as it is with action invocation, except that the contents of the SOAP request and reply use the predefined QueryStateVariable name rather than a particular action name defined by the service.