Statement Nicolas Schiper

Cloud-based applications are everywhere around us. They range from performance sensitive services such as web search, e-commerce, and social networking to mission-critical applications such as air-traffic control and the power grid. These applications tend to be complex, involve a large number of computers, and must face all sorts of failures ranging from power outages and software bugs to malicious attackers. My research interests are centered around making these applications reliable, trustworthy, and scalable. Designing protocols that meet all these requirements is not only a science but also an art and it is a very exciting topic. As such, I design, build, and evaluate protocols to make these services fault-tolerant and scalable, and I use formal methods to provide bug-free code for critical components. As fault-tolerant storage systems have become pervasive in today’s data centers, I have also started investigating the issue of energy-efficient cloud storage. In this line of research, I strive to maximize the performance obtained per Watt by adapting the replication protocol to the workload. My approach to research consists in identifying a problem, precisely stating what properties the solution should guarantee, and exploring the space of solutions. I carry out this exploration both at a theoretical level to distinguish what can be done from what cannot, and at a practical level by building the complete system for it to be extensively evaluated. As a theoretical model cannot fully encompass the complexity of a real system, the initial formal model and algorithms may have to be adapted. This can take the form of refining the fault-model, e.g., in a single tenant cloud hardware and software failures may be more common than malicious attacks; or it may mean trading off some performance for the sake of simplicity. Empirical evaluations often reveal protocol behaviors not foreseen in the design process and are thus essential. To date, I have successfully applied this approach to several projects, various of which I will describe below.