Title: The ∆QSD Paradigm: Designing Systems with Predictable Performance at High Load

Abstract: The ∆Q Systems Development paradigm (∆QSD) is a novel industrially-derived systems development methodology for developing complex real-world distributed systems that directly employs statistical performance metrics from the outset of the system design process and throughout the entire software production life cycle. It uses a stochastic approach to specify system behaviour, using cumulative distribution functions to model both delay and failure together. Experience shows that this is a ‘sweet spot’ that gives good results with little computation requirements. Predictions are accurate when the system model correctly captures both independent and dependent parts. This paradigm has been developed by the Welsh company PNSol over a period of 20+ years, in collaboration with IOG (formerly IOHK), BT, Vodafone, Boeing, Space and Defence, as well as other major companies who focus on the development of reliable high-quality, high integrity, distributed software systems, with strong real-time requirements.In this tutorial, we will present the ΔQSD paradigm, highlighting results from a number of large-scale industrial use cases, and providing hands-on introduction to how to use the process in real-world settings. The tutorial is targeted at researchers, software developers, and managers.