# Digital Manufacturing Platforms in the Industry 4.0 from Private and Public Perspectives
## 2 Literature Review  
The current concept of a digital manufacturing platform has had an evolution since its roots in the sixties when the concept of manufacturing systems came up with advances in computing capability. Since then, it has attracted the attention of researchers who reported their findings in the literature from different perspectives and viewpoints in the past years. This section will review this evolution covering the different terms, names, and features related with digital manufacturing platforms. [PERSON] et al. [17] describe the scope of digital manufacturing and show the evolution of information technology systems in manufacturing, outlining their characteristics and future trends. Digital manufacturing and digital factory concepts in the pre-industry 4.0 era focus mainly on PLM (Product Lifecycle Management) technologies as computer-aided design, engineering, process, product data and life-cycle management, simulation and virtual reality, process control, shop floor scheduling, decision support, decision making, manufacturing resource planning, enterprise resource planning, logistics, supply chain management, and e-commerce systems. As results of digitization advancement, manufacturing system controls have to deal with materials and machines and integration issues that started to come up in manufacturing, as machines and devices in a manufacturing process were no longer isolated but parts of a system, where all the components could be effectively coordinated. To handle integration issues, computer-integrated manufacturing system (CIMS) are starting to be widely adopted by companies. In this context [PERSON] et al. [18] study the perspectives and enablers of integrated and intelligent manufacturing. Increasing opportunities were opened by Internet of Things (IoT) and CPS technologies, which enabled integration to be made wider and more open, comprising three levels of integration in manufacturing--vertical integration, horizontal integration, and end-to-end integration [5]. According to [PERSON] et al. [18] intelligent manufacturing platforms are the enablers to implement intelligent manufacturing technologies. The point of view of industries that are preparing to develop cloud computing platforms based on IoT motivated by business is explained. Predix [19], ThingWorx [20], and Siemens [21] software platforms are described as the main references by the authors. In addition, the authors remark that \"digital twins\" are a significant feature of all such platforms to allow for the prediction of future conditions of productive assets. [PERSON] et al. [22] show an approach of Industry 4.0 for manufacturing systems based on the Smart Factory concept. There is a clear focus on enabling technologies for Smart Factory, such as IoT, IoS, systems integration, and the Cyber-Physical Production System (CPPS). The presented Smart Factory concept relies heavily on distributed computing as a core concept of Industry 4.0, as opposed to the most common manufacturing environments that are centralized. Authors explain the connection between technologies and standards with the role of RAMI 4.0 and its importance in leading the growth of CPPS [23]. [PERSON] et al. [24] present a review of intelligent manufacturing in the context of Industry 4.0. The authors present the major advances in manufacturing technologies as intelligent manufacturing, IoT enabled manufacturing, and cloud manufacturing. They define intelligent manufacturing (also known as smart manufacturing) as a broad concept of manufacturing, with the purpose of optimizing production and product transactions by making full use of advanced information and manufacturing technologies [25]. Intelligent manufacturing system (IMS) are considered to be the next-generation manufacturing system by adopting new models, new forms, and new methodologies to transform the traditional manufacturing system into a smart system.