1. A system for communicating with a first network processor having a first operating environment and a second network processor having a second operating environment different from the first operating environment, comprising: a destination management service (DMS) for registering (a) an application programming interface (API) call and recording an associated operating environment supporting the API call, (b) a unicast address for each of the network processors and the operating environment for the network processor at each unicast address, and (c) a multicast address including the unicast addresses for the network processors; and a network processor application service, responsive to the API call identifying one or more network processors using a call address, for passing an identifier for the API call and the call address to the destination management service and for receiving a set of messaging methods from the DMS for issuing the API call in appropriate form for the network processors addressed by the call address.