More and more data sources today provide a constant data stream, from Internet of Things devices to Social Media streams. It is one thing to collect these events in the velocity they arrive, without losing any single message. An Event Hub and a data flow engine can help here. It’s another thing to do some (complex) analytics on the data. There is always the option to first store them in a data sink of choice, such as a data lake implemented with HDFS/object store, or in a database such as a NoSQL or even an RDBMS, if the volume of events is not too high. Storing a high-volume event stream is feasible and not such a challenge anymore. But doing it adds to the end-to-end latency and it’s a matter of minutes or hours until you can present some results of your analytics. If you need to react fast, you simply can't afford to first store the data and doing the analysis/analytics later. You have to be able to include part of your analytics directly on the data stream. This is called Stream Processing or Stream Analytics. In this talk I will present the important concepts, a Stream Processing solution should support and then dive into some of the most popular frameworks available on the market and how they compare.