You can read the properties of a datapoint using the IzoT Server datapoints resource. The properties include the value, and several attributes, like the name of the datapoint, and timestamp of when it was last updated. See Getting a List of Datapoints for a description of the properties and additional examples.
Get datapoint 2:
http://[hostname]/api/datapoints/2/
Get datapoints with a value equal to on:
http://[hostname]/api/datapoints/?value=on
Get datapoints with "on" in any property, not just the value:
http://[hostname]/api/datapoints/?search=on