Despite the importance of experiment-driven research in the distributed computing community, there has been little progress in helping researchers conduct their experiments. In most cases, they have to achieve tedious and time-consuming development and instrumentation activities to deal with the specifics of testbeds and the system under study. In order to relieve researchers of the burden of those efforts, we have developedEnosLib: a Python library that takes into account best experimentation practices and leverages modern toolkits on automatic deployment and configuration systems.EnosLibhelps researchers not only in the process of developing their experimental artifacts, but also in running them over different infrastructures. To demonstrate the relevance of our library, we discuss three experimental engines built on top ofEnosLib, and used to conduct empirical studies on complex software stacks between 2016 and 2019 (database systems, communication buses and OpenStack). By introducingEnosLib, our goal is to gather academic and industrial actors of our community around a library that aggregates everyday experiment-driven research operations. A library that has been already adopted by open-source projects and members of the scientific community thanks to its ease of use and extension.

By massively adopting OpenStack for operating small to large private and public clouds, the industry has made it one of the largest running software project, overgrowing the Linux kernel. However, with success comes increased complexity, facing technical and scientific challenges, developers are in great difficulty when testing the impact of individual changes on the performance of such a large codebase, which will likely slow down the evolution of OpenStack. Thus, we claim it is now time for the scientific community to join the effort and get involved in the development of OpenStack, like it has been once done for Linux. In this spirit, we developed Enos, an integrated framework that relies on container technologies for deploying and evaluating OpenStack on any testbed. Enos allows researchers to easily express different configurations, enabling fine-grained investigations of OpenStack services. Enos collects performance metrics at runtime and stores them for post-mortem analysis and sharing. The relevance of the Enos approach to reproducible research is illustrated by evaluating different OpenStack scenarios on the Grid'5000 testbed.

Accountability policies for the enforcement of the responsible stewardship of personal data have to support the gathering of information at all levels of the service stack and across different policy domains, for instance, for the retrospective enforcement of transparency and remediation properties. Existing approaches to accountability, however, often do not meet these requirements and corresponding implementation support is lacking. In this paper we show how expressive accountability policies can be defined in terms of policy domains, accessible data at all levels of the service stack, and preventive and retrospective mechanisms. Additionally, we present a notion of accountability schemes that support the constructive implementation of our accountability policies. Finally, we motivate and apply our approach in the context of real-world attacks to OAuth-based authorization and authentication protocols.

Existing approaches to the adaptation of workflows over Web services fall short in two respects. First, they only provide, if ever, limited means for taking into account the execution history of a workflow. Second, they do not support adaptations that require modifications not only at the service composition level but also at the levels of interceptors and service implementations. This is particular problematic for the enforcement of security properties over workflows: enforcing authorization properties, for instance, frequently requires execution contexts to be defined and modifications to be applied at all these abstraction levels of Web services. We present two main contributions in this context. First, we introduce workflow adaptation schemas (WAS), a new notion of generic protocol-based workflow adapters. WAS enable the declarative definition of adaptations involving complex service compositions and implementations. Second, we present two real-world security issues related to the use of OAuth 2.0, a recent and widely used framework for the authorization of resource accesses. As we motivate, these security issues require history-based adaptations over different abstraction levels of services. We then show how to resolve these issues using WAS.