This book constitutes the refereed proceedings of the 16th IFIP WG 2.13 International Conference on Open Source Systems, OSS 2020, held in Innopolis, Russia, in May 2020.* The 12 revised full papers and 8 short papers presented were carefully reviewed and selected from 42 submissions. The papers cover a wide range of topics in the field of free/libre open source software (FLOSS) and discuss theories, practices, experiences, and tools on development and applications of OSS systems, with a specific focus on two aspects:(a) the development of open source systems and the underlying technical, social, and economic issue, (b) the adoption of OSS solutions and the implications of such adoption both in the public and in the private sector. *Due to the COVID-19 pandemic, the conference was held virtually.

This open access book provides information how to choose and collect the appropriate metrics for a software project in an organization. There are several kinds of metrics, based on the analysis of source code and developed for different programming paradigms such as structured programming and object-oriented programming (OOP). This way, the book follows three main objectives: (i) to identify existing and easily-collectible measures, if possible in the early phases of software development, for predicting and modeling both the traditional attributes of software systems and attributes specifically related to their efficient use of resources, and to create new metrics for such purposes; (ii) to describe ways to collect these measures during the entire lifecycle of a system, using minimally-invasive monitoring of design-time processes, and consolidate them into conceptual frameworks able to support model building by using a variety of approaches, including statistics, data mining and computational intelligence; and (iii) to present models and tools to support design time evolution of systems based on design-time measures and to empirically validate them. The book provides researchers and advanced professionals with methods for understanding the full implications of alternative choices and their relative attractiveness in terms of enhancing system resilience. It also explores the simultaneous use of multiple models that reflect different system interpretations or stakeholder perspectives.

This volume constitutes selected papers presented at the First International Conference on Frontiers in Software Engineering, ICFSE 2021, hekd in Innopolis, Russia, in June 2021. The 13 presented full papers were thoroughly reviewed and selected from 37 submissions. The papers present discussion on such topics as software engineering tools and environments; empirical software engineering; model-driven and domain-specific engineering, human factors and social aspects of software engineering, cooperative, distributed, and global software engineering, component-based software engineering, software metrics, and software engineering for green and sustainable technologies.