Reaqtor: Reliable Rx at Scale for Event Processing

22nd June 2021 · 74 min watch

By Carmel Eve Software Engineer II

By Ian Griffiths Technical Fellow I

Discover Reaqtor, an open-source, scalable event processing service based on Rx, used in Microsoft's Cortana & Office 365. Learn about its unique features.

About this talk

.NET Oxford

The Reactive Extensions for .NET (Rx) is one of the most influential technologies to have emerged from the .NET ecosystem. (Its influence on other platforms has been so pervasive that its origins in .NET are sometimes forgotten.)

The team that created Rx did not rest on their laurels: they used Rx as the basis for developing a distributed, reliable, and extremely scalable event processing service. Reactor, as it was then called, has been integral to some of Microsoft's most widely used services for many years, including Cortana and Office 365, but although Microsoft has talked in public about it a few times, it has never been available for use outside of Microsoft—until now.

On May 18th 2021, Bart de Smet, made Reaqtor (its new name) open source, as a .NET-Foundation-sponsored project.

This talk will explain what makes Reaqtor different from other high-scale event processing systems. It will also show some of the foundational components that have been released as part of this, most notably 'Bonsai', a mechanism for serializing computations based on .NET's expression tree system, and which is central to how Reaqtor works.

About the presenters

Carmel Eve

Carmel is a software engineer and LinkedIn Learning instructor. She worked at endjin from 2016 to 2021, focused on delivering cloud-first solutions to a variety of problems. These included highly performant serverless architectures, web applications, reporting and insight pipelines, and data analytics engines. After a three-year career break spent travelling around the world, she rejoined endjin in 2024.

Carmel has written many blog posts covering a huge range of topics, including deconstructing Rx operators, agile estimation and planning and mental well-being and managing remote working.

Carmel has released two courses on LinkedIn Learning - one on the Az-204 exam (developing solutions for Microsoft Azure) and one on Azure Data Lake. She has also spoken at NDC, APISpecs, and SQLBits, covering a range of topics from reactive big-data processing to secure Azure architectures.

She is passionate about diversity and inclusivity in tech. She spent two years as a STEM ambassador in her local community and taking part in a local mentorship scheme. Through this work she hopes to be a part of positive change in the industry.

Carmel won "Apprentice Engineer of the Year" at the Computing Rising Star Awards 2019.

Ian Griffiths

Ian has worked across an extraordinary breadth of computing - from embedded real-time systems and broadcast television to medical imaging and cloud-scale architectures. As Technical Fellow at endjin, he brings this deep cross-domain experience to bear on the hardest technical problems.

A 17-time Microsoft MVP in Developer Technologies, Ian is the author of O'Reilly's Programming C# 12.0 and one of the foremost authorities on the C# language and high-performance .NET development. He's a maintainer of Reactive Extensions for .NET, Reaqtor, and endjin's 50+ open source projects.

Ian has created Pluralsight courses on WPF fundamentals, WPF advanced topics, WPF v4, and the TPL, and has given over 20 talks at conferences worldwide. Technology brings him joy.