This invention pertains to a brewing head assembly of a coffee machine that enables easy insertion and removal of the filter as well as locking of the filter and the filter holder into the brewing head to form a water-tight seal under pressure. The plurality of virtual machine instances can be configured based on a predetermined set of configurations. Processes for producing the preparations are also described, including processes comprising extrusion of a melt impregnated with a physiologically acceptable volatile blowing agent. The data is then read from the front end schema node to the back end schema node via the front end data object and the back end data object according to the common interface and the common set of property types.