1. A method for controlling a manufacturing process of a plant via a MES system, which comprises the steps of: a) providing the MES system with a product definition model containing MES entities of different types for defining an exchange of information among the MES entities, wherein the MES entities contain at least one product-related entity; b) providing to the MES entities, associating methods for working with a given product definition of a given final material modeled according to the product definition model; c) within the product definition model, defining for the product-related entity a set of product-related entities referencing the product-related entity and each other via a nested structure, the product-related entity is hereinafter referred as a parent product-related entity and the set of product-related entities is hereinafter referred as a set of nested product-related entities; d) within the product definition model, defining for the product-related entity a set of product-related parameters to define information that may be sent to the MES system to control a plant manufacturing process of the given final material; e) within the product definition model, defining an additional entity called parameter exchange definition for providing a tool for defining how data of product-related parameters of the set of nested product-related entities and of the parent product related entity are to be exchanged among each other at run-time by the MES system; f) at engineering time, building a given product definition of the given final material by inserting the entities of steps c), d), e) and by specifying how the set of product-related parameters are exchanged; g) at run time, instantiating the entities of step f) into run-time production requests objects obtained by the given product definition; and h) at run time, controlling the plant manufacturing process by executing the production requests of step g).