Matrix is an open protocol and open network for decentralised real-time communication; shifting control over communication from the big proprietary silos back to the general population of the Internet. In 2016 we added E2E Encryption based on the Double Ratchet, and since then have been working away on getting the encryption so polished that we can transparently turn it on by default everywhere. In this talk, we'll show how we have finally done this, what...

Kubernetes is complex, and extremely vulnerable. In 2019 we explored the complexity of the Kubernetes codebase, and the antipatterns therein. This year we want to look at understanding how we observe our cluster at runtime. Let's live code some C and C++ and explore the libraries that bring Wireshark, Falco, and Sysdig to life. We concretely demonstrate how we are able to audit a Kubernetes system, by taking advantage of auditing the kernel's syscall information...

Upgrading big components in Linux distributions is hard. But integrating them while minimizing regressions (for stable distributions) and not slowing down release pace (for rolling releases) requires a lot of process and tooling. Let's deep dive in those. Over the previous months, openSUSE and SUSE teams have worked together on integrating latest GNOME release (3.34) in their various distributions, while minimizing duplicated work and sharing as much code as possible. We'll describe how it was...

A bespoke OSHW HDMI video capture solution is being developed for use at FOSDEM and other open source conferences. This talk will explain the what, why, how and hopefully when. FOSDEM is unique in that it has 750+ talks on two days, with more than 28 parallel tracks. All are captured and streamed out live, and a sanitised version of each talk is re-encoded for separate viewing after the event. For each track, there are...

Using Terraform is often simple, extending it to do what YOU want, can be challenging (or “impossible”). Want to manage unsupported resources? Maintain lots of resources? Integrate non-integrable? The talk is an advanced guide about HOW to extend, integrate and execute Terraform to get things DONE. If you’ve been using Terraform just by following the official documentation, you are not getting all from it. As soon as one cloud provider announces a new service or...

Node.js is now over a decade old. With Node.js 12 just entering into long-term support, and Node.js 13 being released, let us take a look at the new features, breaking changes, and what is next. Node.js is an open-source, cross-platform, JavaScript runtime environment that executes JavaScript code outside of a browser. Corporate users of Node.js software include Groupon, IBM, LinkedIn, Microsoft, Netflix, PayPal, SAP, Walmart, and Yahoo!.

Liouville conformal field theory (LCFT hereafter), introduced by Polyakov in his 1981 seminal work "Quantum geometry of bosonic strings", can be seen as a random version of the theory of Riemann surfaces. LCFT appears in Polyakov's work as a 2d version of the Feynman path integral with an exponential interaction term. Since then, LCFT has emerged in a wide variety of contexts in the physics literature and in particular recently in relation with 4d supersymmetric...

Früher enthielt das Umsatzsteuergesetz (§ 2 Abs. 3 UStG a.F.) eine Regelung über den „Betrieb gewerblicher Art“. Der Begriff wurde aus dem Gesetz entfernt. Die Auswirkungen für die Steuerpflicht von Bibliotheken sind oft noch unbekannt.

Nasreddin will auf dem Markt einen Truthahn verkaufen und stellt sich neben den Besitzer eines Papageis, der für sein Tier zehn Pfund verlangt. Der erste Interessent schreit: „Bist du wahnsinnig? Der Papagei dort kann sprechen und kostet zehn Pfund, und du verlangst zwanzig?“ „Mein Truthahn kann mehr als sprechen,“ erwidert Nasreddin. „Er kann zuhören.“ Und ist also mehr wert - so die Moral der Geschichte. Die Fähigkeit zuzuhören wird hier in einfacher und anschaulicher Weise...

Vita is a high-performance IPsec VPN gateway designed with medium and large network operators in mind. It is written in a high-level language (Lua) using the Snabb networking toolkit and achieves high performance via networking in userspace, i.e. bypassing the kernel network stack. This talk will discuss Vita and how it was developed using Snabb. Topics include: fast software networking using a dynamic, high-level language; cryptographic ciphers implemented in software software accelerated by x86 extensions;...

Have you ever needed to get some additional write throughput from MySQL ? If yes, you probably found that setting sync_binlog to 0 (and trx_commit to 2) gives you an extra performance boost. As all such easy optimisation, it comes at a cost. This talk explains how this tuning works, presents its consequences and makes recommendations to avoid them. This will bring us to the details of how MySQL commits transactions and how those are...

Mgmt is a real-time automation tool that is fast and safe. One goal of the tool is to allow users to model and manage infrastructure that was previously very difficult or impossible to do so previously. The tool has two main parts: the engine, and the language. This presentation will have a large number of demos of the language. To showcase this future, we'll show some exciting real-time demos that include scheduling, distributed state machines,...

The Mainz Acoustic Levitator (M-AL) is an experimental setup placed in the walk-in cold chamber of the Vertical Wind Tunnel Laboratory of the Johannes Gutenberg University of Mainz. In the M-AL immersion freezing of water droplets containing different types of ice nucleating particles (INP) was investigated at sub-zero temperatures down to -23 °C. This video shows an example of the freezing of a supercooled droplet in M-AL.

This lecture offers detailed analysis of the Lorentz transformations which relate the coordinates of an event in two frames in relative motion. It is shown how length, time and simultaneity are relative. 00:00 - Chapter 1. Describing an Event with Two Observers 33:58 - Chapter 2. The Relativity of Simultaneity 41:57 - Chapter 3. Time Dilation 53:41 - Chapter 4. The Twin Paradox 01:00:02 - Chapter 5. Length Contraction

The four-vector is introduced that unifies space-time coordinates x, y, z and t into a single entity whose components get mixed up under Lorentz transformations. The length of this four-vector, called the space-time interval, is shown to be invariant (the same for all observers). Likewise energy and momentum are unified into the energy-momentum four-vector. 00:00 - Chapter 1. Recap—Consequences of the Lorentz Transformations 06:25 - Chapter 2. Causality Paradoxes: "Killing the Grandmother" 15:22 - Chapter...

This lecture continues the topic of harmonic motions. Problems are introduced and solved to explore various aspects of oscillation. The second half of the lecture is an introduction to the nature and behavior of waves. Both longitudinal and transverse waves are defined and explained. 00:00 - Chapter 1. Free Vibration: Oscillation Under F=0 08:20 - Chapter 2. Initial Conditions at Start of Oscillation 18:52 - Chapter 3. Solution to Harmonic Equation under Driving Force 30:01...

The focus of the lecture is on fluid dynamics and statics. Different properties are discussed, such as density and pressure. Archimedes' Principle is introduced and demonstrated through a number of problems. The final topic of the lecture is Bernoulli's Equation. 00:00 - Chapter 1. Introduction to Fluid Dynamics and Statics — The Notion of Pressure 04:14 - Chapter 2. Fluid Pressure as a Function of Height 20:49 - Chapter 3. The Hydraulic Press 26:32 -...

This is the first of a series of lectures on thermodynamics. The discussion begins with understanding "temperature." Zeroth's law is introduced and explained. Concepts such as "absolute zero" and "triple point of water" are defined. Measuring temperature through a number of instruments is addressed as well as the different scales of measurement. The second half of the lecture is devoted to heat and heat transfer. Concepts such as "convection" and "conduction" are explained thoroughly. 00:00...

This lecture continues the topic of thermodynamics, exploring in greater detail what heat is, and how it is generated and measured. The Boltzmann Constant is introduced. The microscopic meaning of temperature is explained. The First Law of Thermodynamics is presented. 00:00 - Chapter 1. Recap of Heat Theory 11:54 - Chapter 2. The Boltzman Constant and Avogadro's Number 18:50 - Chapter 3. A Microscopic Definition of Temperature 30:15 - Chapter 4. Molecular Mechanics of Phase...