The present invention is directed to facilitating communications and interoperability between/among applications and services. Such applications and services may be running on or associated with disparate platforms. The apparatus of the present invention provides for a message set that can be used by services to advertise available services, and by applications to identify desired services. According to certain embodiments, applications may subscribe to available services. In a further aspect of some embodiments, applications executable on and services available from disparate platforms are not required by themselves to support communications between/among the platforms. Instead, such support may be obtained from facilities that are provided as part of the platform itself.