1. A method for registering a service or resource offered by a virtual machine, the method comprising: monitoring, by a registry in cooperation with a virtual machine manager associated with the virtual machine, an event indicating change of operational state of the virtual machine; and updating, by the registry, a registration of the service or resource offered by the virtual machine with the registry, in response to the monitored event indicating change of operational state of the virtual machine; wherein the registry includes registration information of the service or resource offered by the virtual machine, the registry is searchable for the service or resource, and the service or resource is advertised by the virtual machine to one or more other virtual machines through the registry.