A lot of educational tools about application streaming are concentrated on examples of code. How to use some library or framework? But the working application is not just a code, but such questions are where to get data and put it, how long to store, how to update application and data. We will talk about these things and what you need to know in order to successfully operate a streaming application in production. This talk is based on Plumbr architecture which processes billions of messages each month for several years.