1. A method for a client node to request services of an application identified by a logical identifier, the application executing at an application node that is identified by a physical identifier, the method comprising: receiving at the client node from a logical routing layer of a node other than the client node mappings of logical identifiers to physical identifiers, each mapping being registered with the logical routing layer by an application identified by the logical identifier of the mapping and for an application node identified by the physical identifier of the mapping, the application identified by a logical identifier being hosted on the application node identified by the mapped-to physical identifier; and after receiving the mappings, identifying at the client node the logical identifier of an application to which the client node is to send a request for service; identifying at the client node the physical identifier corresponding to the identified logical identifier using the received mappings; and sending by the client node to a physical routing layer the request for service, the request being addressed to the identified physical identifier wherein the physical routing layer of the client node determines a network identifier for the addressed physical identifier and routes the request for service to the network identifier for servicing of the request by the application identified by the logical identifier hosted on the application node identified by the mapped-to physical identifier at the determined network identifier.