# Context-Aware Systems Architecture in Industry 4.0: A Systematic Literature Review
## 2 Background
### Industry 4.0  
I4.0 refers to the Fourth Industrial Revolution, characterised by the integration of information and communications technology (ICT) into industrial processes [14; 15; 16], and government entities and industries have acted to take advantage of the benefits that this new wave of innovation represents [17]. The presentation of the I4.0 concept occurred during the Hannover Fair in 2011 as a German strategic initiative to take on a pioneering role in manufacturing industries [18]. Now, many countries have public programs devoted to I4.0 [19], which refers to a set of technologies applied to the industrial sector, such as Internet of Things (IoT), cyber-physical computing (CPS), artificial intelligence (AI), cloud computing, and big data, among others.  
Among the technologies presented above, according to [PERSON] et al. [20], CPS and the Industrial Internet of Things (IIoT) concept play an essential role in the emergence of the I4.0 paradigm, and researchers are exploring it to accompany the digital transformation in the industrial sector. In recent years, the trend towards customer-oriented production has driven the evolution towards cyber-physical production systems (CPPS) based on CPS. This includes autonomous, cooperative, and interconnected actors at all production levels and adopts an open and loosely coupled architecture, rather than following the traditional ISA-95 automation pyramid [21]. In addition, the digital twin (DT) concept, one of the leading technologies for the implementation of CPS [22], requires the creation of a virtual and exact copy of a physical object or system, including its properties and its environment [23], and constantly synchronises with its physical system through continuous data transfer [24].  
The focus of I4.0, according to [PERSON] et al. [18], lies in achieving horizontal, vertical, and end-to-end integration in an ecosystem where physical and virtual actors, humans, and machines live. The horizontal integration of these actors promotes collaboration and integration between different entities within the value chain, enabling continuous communication and coordination while providing a complete solution to departments. End-to-end integration refers to systems, processes, and data integration throughout the value chain or production system, which integrates the different stakeholders.  
Later, in 2019, automation, interoperability, and sustainability were introduced as strategic fields presented by the Platform for I4.0 in the document \"2030 Vision for Industrie 4.0\" [25], which describes this new global and digital ecosystem that is more dynamic, collaborative, and focused on data. Other works have discussed the concepts, characteristics, and principles that effectively materialise innovations in global industry. [PERSON] et al. [26], [PERSON] et al. [27], and [PERSON] [28] listed five main characteristics associated with achieving the objectives of I4.0: the digitisation and personalisation of production; automation and adaptation; human-machine interaction; value-added services and businesses; and interoperability. In addition, [PERSON] et al. [29] identified four design principles: interconnection, information transparency, decentralised decisions, and technical assistance. Finally, [PERSON] [28] stated that the principles of I4.0 are interoperability, virtualisation, decentralisation, real-time updating, service orientation, and modularity.  
The popularity of the I4.0 paradigm has grown in recent years, creating the conditions for its implementation [30]. Although I4.0 was introduced a decade ago, there are many barriers, like new employee skills, data security and privacy, system standardisation, and high investments, mainly in medium-sized enterprises (SMEs) [31], and a lack of understanding of the benefits of I4.0 [32]. Consequently, according to [PERSON] and [PERSON] [33], in the majority of manufacturing companies, particularly those in developing economies, I4.0 remains more of an aspiration than a reality.