Command handlers are services If we start from the command redux post by Ayende. In actual shopping scenarios we need to deal with not a clear script of actions that can be executed in a sequential manner. Instead we have a unidirectional wizard-style flow where the customer is redirected from the shopping site to payment provider and back. Let us ignore these complexities and look at the following: var placeOrderCommand = new CompositeCommand( new RegisterOrderCommand(), new ReserveStockComman[...]