Mind Your Outcomes: The ∆QSD Paradigm for Quality-Centric Systems Development and Its Application to a Blockchain Case Study

This paper directly addresses a long-standing issue that affects the development of many complex distributed software systems: how to establish quickly, cheaply, and reliably whether they can deliver their intended performance before expending significant time, effort, and money on detailed design and implementation. We describe ΔQSD, a novel metrics-based and quality-centric paradigm that uses formalised outcome diagrams to explore the performance consequences of design decisions, as a performance blueprint of the system. The distinctive feature of outcome diagrams is that they capture the essential observational properties of the system, independent of the details of system structure and behaviour. The ΔQSD paradigm derives bounds on performance expressed as probability distributions encompassing all possible executions of the system. The ΔQSD paradigm is both effective and generic: it allows values from various sources to be combined in a rigorous way so that approximate results can be obtained quickly and subsequently refined. ΔQSD has been successfully used by a small team in Predictable Network Solutions for consultancy on large-scale applications in a number of industries, including telecommunications, avionics, and space and defence, resulting in cumulative savings worth billions of US dollars. The paper outlines the ΔQSD paradigm, describes its formal underpinnings, and illustrates its use via a topical real-world example taken from the blockchain/cryptocurrency domain. ΔQSD has supported the development of an industry-leading proof-of-stake blockchain implementation that reliably and consistently delivers blocks of up to 80 kB every 20 s on average across a globally distributed network of collaborating block-producing nodes operating on the public internet.publishedVersio

Service Futures, Proceedings of the fourth Service Design and Service Innovation Conference

ServDes2014 explores how Service Design is contributing to ‘Service Futures’ and how it is developing as a field of research and practice. We have witnessed how the concept and role of services in the economy and society have come a long way since its first definitions and studies. Services have moved from being a peripheral activity in a manufacturing - centred economy; to an engine for growth and society driven innovation. This transformation has been fully recognised with a flourishing of service innovation and service research studies aimed at deepening understanding; and at supporting the development of services both as a sector and as a concept. We suggest that Service Design is closely following this transformation. Starting from its initial focus on service interactions and experiences; Service Design research and practice have entered more strategic and transformational roles; dealing with issues of organisational change; system design; sustainability and social change; amongst others. Increasingly; Service Design is considering ways to integrate and collaborate with other service related disciplines. Also; questions are emerging on the future of this field; considering the growing areas of application and the expansion of the concept of service itself. ServDes2014 has brought these recent discussions and transformations to the fore and offered an ideal place to collectively reflect on and imagine that future. ServDes.2014 ran over three days: The first day was dedicated to practical explorations of Service Design with eight workshops led by both practitioners and academics; The second day was mostly focused on (long and short) papers presentations organised in three parallel sessions and two extra workshops; The third and final day was partly dedicated to papers presentation and came to an end with three parallel forums exploring the future of Service Design Research and Education and their relationship with Social Innovation. Working at the boundaries of Service Design; Digital and Social Innovation; the keynote speaker Dominic Campbell (Futuregov); projected novel spaces and responsibilities for Service Design in relation to complex societal transformational challenges; while Prof. Pelle Ehn (Malmö University); positioned it within a historical retrospective of Participatory Design in a constant search for more democratic (service) design practices. The conference was organised around five main themes which are reflected in the proceedings structure: Emerging Directions for Service Design; Design for Service Innovation and Transformation; Service Design and Implementation; Novel Service Design Frameworks and Tools; Service Design Across Organisations. Thanks to everyone who contributed and participated to this conference; and we look forward ServDes.2016 further developments and ideas