comments on sensor API draft (2nd set)

Passing on comments from others on sensor API draft 10 November 2011 version, http://dev.w3.org/2009/dap/system-info/Sensors.html



1.      Section 6.1.1 lists for Attribute status: “disconnected” – this state is not used. I suggest to remove it or define its use.
2.      Section 6.1.2 functions endWatch, read and startWatch refer to ILLEGAL_STATE exceptions, which are not defined. In my opinion, this should probably be INVALID_STATE_ERR (http://www.w3.org/TR/DOM-Level-3-Core/core.html#DOMException-INVALID_STATE_ERR<http://www.w3.org/TR/DOM-Level-3-Core/core.html> )
3.      Section 8.1 Sensor Error defines the PERMISSION_DENIED error code to be a negative -100 value even though the type is unsigned short.
4.      Important:
Section 6.1.2 [Constructor(SensorOptions options)]:
This paragraph describes the algorithm for sensor lookup at construction time of the object.
From an implementer’s perspective, this requires a DOM implementation to wrap a potentially asynchronous operation (cmp. findSensors()) into a synchronous constructor.
I think this should be rewritten to queue a sensor lookup task and always return a SensorConncetion object in state new. When the lookup task completes, state transitions should occur which are signaled through “onstatuschange” or “onerror”. In  the case of a successful lookup, the state should change to open. In the case of failure, it should transition to error. As mentioned: Both signaled through the corresponding status change handlers.
5.      In the implementation it has been useful to add a return code NO_SENSOR_FOUND = 101 to section 8.1 in cases where a lookup didn’t come back with any sensor result but no unforeseen error occurred.