nonblocking is a SIDL method attribute. A nonblocking method is split into two parts. The invocation, method_send(), makes the call and immediately returns a sidl.rmi.Ticket. Later, the Ticket can be used to check if the method has returned, and retrieve the out arguments if it has with method_recv(). Nonblocking methods are really only useful with RMI where it allows the client to mix computation and communication more freely.