# System of Systems Lifecycle Management--A New Concept Based on Process Engineering Methodologies
## 9 Conclusions  
The main novelty of the paper is that it introduces a newly developed SoSLM approach. To understand the motivation, the related literature was discussed, highlighting the main gaps in existing lifecycle management models. We performed a comprehensive analysis of the most widely used process engineering methodologies and ITSM frameworks, and using the results, in the first step, we developed a generic PLM model according to the reinterpreted product definition and, in the second step, based on the created PLM model, a SoSLM model was defined to meet the identified SoS-related requirements. The resulting model was enhanced with the service-oriented approach. Hence, the paper presents qualitative and quantitative research artifacts as well. The PLM model yielded quantitative research, where the old PLM approaches were enhanced and product lifecycle phases were fine-tuned according to Industry 4.0 expectations. Still, the real novelty here is the appearance of a new core feature in the model, the information sharing capability that underlies Industry 4.0-compliant systems. Reflecting on this, a further important finding of the research work is the use of IoT-based digital frameworks and platforms for achieving new features and managing phases during the whole lifecycle. The SoSLM model can be considered a qualitative artifact, which is the paper's main topic, and solves the SoS-related lifecycle management problems. The SoSLM model, on the one hand, integrates SLM and PLM models, complemented by the ability of information sharing. On the other hand, it adds industry best practices to address the area-specific problems presented in gap analysis. The SoSLM model is verified by a presented use case; furthermore, operation of the developed system was also validated in real circumstances using the Arrowhead framework that addresses interoperability and integrability issues primarily for the IIoT domain. The model covers the needs of SOA and SLM, thanks to the ITIL terminology, but it is also extended by the main PLM lifecycle phases and processes, i.e., from researchthrough development, deployment, continuous management, and monitoring up to the information feedback. In general, the paper can help the research community as well as the system operators in several areas. On the one hand, it provides useful and comprehensive surveys on lifecycle management, process engineering, and ITSM frameworks; furthermore, it can serve as useful guidance for creating specific lifecycle management approaches. On the other hand, it includes an enhanced PLM model and a newly designed SoSLM model that can help operators in system management tasks of smart ecosystems, mainly in the SOA context. In addition to the benefits, the paper also covered the limitations of the SoSLM model. The SoSLM models the lifecycle from an architectural point of view; therefore, it does not handle, for example, the detailed description of coding techniques. The same is true for the flow of information. Due to the SoSLM model's nature, continuous information sharing can be provided, but the SoSLM does not formulate a specific methodology for that particular function. Thus, compared with the presented lifecycle models, it can be stated that both SoSLM and the newly developed PLM models can be applied to several levels in different areas. Still, in some cases, they do not answer the context-specific questions in detail. Regarding use, the model has been applied mostly on prototype or beta implementations. Thus, just as the current form of the model has evolved, one of the future works is still to apply and observe the model in more production environments, by which it can be further developed. Moreover, Industry 4.0 elements are still under standardization; therefore, the requirements for PLM and SoSLM could change in the future. The models must adapt to changing industrial trends and the actual relevance of the presented models needs further and continuous analysis and tests. Conceptualisation, D.K. ; methodology, D.K., P.V., F.L. ; software, D.K., F.L.