Any system built on event sourcing principles needs to deal with event versioning soon after it goes into production. Systems that handle long lasting processes or contain long living entities may face additional challenges: how to optimize building states from large number of events? Should event streams be kept short? And what is the best approach to the design of systems where entities live for years, outliving technologies and development teams?

Come to my talk, and I will share the experience and views of our team where we are developing and maintaining applications for a large media company. Our choices are opinionated, but we have spent years on the design and implementation of our services, and we are modelling entities that live for decades.