Self-improving System Integration – Status and Challenges After Five Years of SISSY Kirstie Bellman ∗ , Jean Botev ‡ , Ada Diaconescu † , Lukas Esterle ¶ , Christian Gruhl § , Chris Landauer ∗ , Peter R. Lewis ¶ , Anthony Stein ∗∗ , Sven Tomforde §†† , and Rolf P. W¨ urtz ‖ ∗ Topcy House Consulting, US, Email: bellmanhome@yahoo.com, topcycal@gmail.com § Intelligent Embedded Systems, University of Kassel, Germany, Email: cgruhl@uni-kassel.de ‡ University of Luxembourg, Email: jean.botev@uni.lu † Telecom-Paris Tech, France, Email: ada.diaconescu@telecom-paristech.fr ¶ Aston University, Birmingham, UK, Email: p.lewis@aston.ac.uk, l.esterle@aston.ac.uk ‖ Ruhr Universit¨ at Bochum, Germany, Email: rolf.wuertz@ini.rub.de ∗∗ University of Augsburg, Germany, Email: anthony.stein@informatik.uni-augsburg.de †† University of Passau, Germany, Email: sven.tomforde@uni-passau.de Abstract—The self-improving system integration (SISSY) ini- tiative has emerged in recent years in response to a systems en- gineering trend towards the organisation of open, interconnected systems integrating a large set of heterogeneous and autonomous subsystems. Based on the idea to equip subsystems with capabil- ities to assess and maintain their own integration status within the overall system composition, a variety of concepts, techniques, and contributions have been proposed and fruitfully discussed at the particular events of the underlying workshop series. In this article, we summarise and categorise these research efforts and derive a roadmap towards full-scale SISSY systems. I. I NTRODUCTION Information and communication technology (ICT) pervades every aspect of our daily lives. This inclusion changes our communities and all of our human interactions. It also presents a significant set of challenges to correctly designing and integrating our resulting technical systems. For instance, the embedding of ICT functionality in more and more devices (such as household appliances or thermostats) leads to novel interconnections and a changing structure of the overall sys- tem. Not only technical systems are increasingly coupled, a variety of previously isolated natural and human systems have consolidated into a kind of overall system of systems – an interwoven system structure [1]. This change of structure is fundamental and affects the entire production cycle of technical systems – standard system integration and testing is not feasible any more because it does not cope with the dynamic changes in a relatively open system of goals, behaviours, relationships, and even partici- pating systems. Also, unlike many current complex systems, the integrating systems do not have any or little control or authority over each other, and indeed, there may be no central authority or control for most of the behaviours or goals of the system. There may be some standards, rules, or governing body for certain aspects of the system, but like the Internet, many goals and behaviours may be brought in an unregulated manner by participating users and systems. Furthermore, there may be limited or no knowledge of other participating systems available to other systems, as often is the case in the classical engineering of complex System of Systems (SoS). The increasingly complex challenges of developing the right type of modelling, analysis, and infrastructure for de- signing and maintaining ICT infrastructures has continued to motivate research in the self-organising systems, Autonomic and Organic Computing systems communities – resulting in the vision of self-improving system integration (SISSY). The goal of the SISSY initiative is to study novel approaches to system of system integration and testing by applying self-* principles; specifically, approaches are investigated that allow for a continual process of self-integration among components and systems that is self-improving and evolving over time towards an optimised and stable solution. Although research in self-organising systems – such as the Organic Computing (OC) [2] and Autonomic Comput- ing (AC) [3] initiatives – has seen an exciting decade of development with considerable success in building individ- ual systems, OC/AC is faced with the difficult challenge of integrating multiple self-organising systems, and integrating self-organising systems with traditionally engineered ones as well as naturally occurring human organisations. Meanwhile, although there has been important progress in system-of- systems methodologies (e.g. Service-oriented Architectures [4] and cloud technology [5]), many of these developments lack scalable methods for rapidly proving that new configurations of components/subsystems are correctly used or their changes verified or that these frameworks have pulled together the best possible context-sensitive configuration of resources for some purpose of a user or another system. This article summarises the research activities in the context of SISSY over the last five years and aims at consolidating them into a preliminary blueprint for SISSY systems. We therefore categorise the different contributions from the past events of the SISSY workshop – 2014 at IEEE International Conference on Self-Adaptive and Self-Organising Systems (SASO14) [1] in London, UK, 2015 at IEEE/ACM Interna- 160 2018 IEEE 3rd International Workshops on Foundations and Applications of Self* Systems 978-1-5386-5175-9/18/$31.00 ©2018 IEEE DOI 10.1109/FAS-W.2018.00042