1. A method in a computing device for exchanging context attributes through an application programming interface of a facility, the method comprising: with at least one processor: receiving an enumeration request through the application programming interface for an enumeration of context attribute types; in response to receiving the enumeration request, providing to a requesting attribute consumer a list of context attribute types available from the facility, each of the context attributes being identified by a respective name; receiving an invocation request to provide an attribute value, the invocation request being generated by the requesting attribute consumer, the invocation request identifying the type of the context attribute whose value is to be provided, the context attribute type being in the list and being identified in the invocation request by the respective name in the list; and in response to receiving the invocation request, providing a value for the identified attribute to the requesting attribute consumer.