Idilia Batchkova DEVELOPMENT OF MANUFACTURING EXECUTION SYSTEMS USING FORMAL APPROACHES Manufacturing Execution Systems are complex reactive real time systems, which exhibit various behavioural aspects such as communications between components, state transformation inside components, and real-time constraints on the communications and state changes. <...> Their development on the base of traditional development processes, including manual coding and follow-up testing and simulation may lead to costly errors, lower quality, delayed delivery and high overall development costs. <...> The paper analyses the currently state of the art in the development of MES and the methods for formal specification and verification of real time software systems. <...> Some approaches for integrated application of different kind of semiformal and formal methods are presented and discussed. 1. <...> INTRODUCTION The rapid changes in the market demands require manufacturing systems to be sufficiently agile in order to allow rapid adjustments in product and volume mix and this way to promote competitive and sustainable growth. <...> Most of the currently used enterprise and control systems are disconnected and this way lacks the support for interoperability and collaboration, needed for an enterprise-wide integration. <...> The Manufacturing Execution Systems (MES) are the core framework in overcoming these disadvantages and enabling real time enterprises. <...> An analysis of the currently state of the art in development and applying MES shows that most of presently used MES systems are based on a traditional technology and are inflexible, with monolithic architecture and limited scope. <...> Until now the core research topics in the domain of MES ware in defining the main functionalities of MES, the adoption of standardized software interfaces with enterprise systems through using a widely accepted MES Reference architecture and determining the relationships between their components. <...> Section 2 of the paper gives a more detailed overview of MES including definition, basic functions and currently state of the art in the MES development life cycle. <...> The main difficulties in MES development and application are summarized. <...> In order to overcome the difficulties in MES development life cycle, new approaches are needed. <...> The new challenges in this direction are to raise the level of abstraction further to the model level by using formal methods and rely on automatic and semi-automatic code generation in order to produce code in traditional programming language. <...> Using formal <...>