The manufacturing executive system is a main module of an enterprise information system. It is similar to ERP (enterprises resources planning) but it focuses more on shop floor operation and management. Langenwalter (2000) defined MES as “an
on-line, integrated, computerized system that is the accumulation of methods and tools used to accomplish production”. In our model, the MES comprises the MRP based production management, shop floor control, and facilities management (see Figure 2)