Streaming apps tend to grow in complexity. Streaming computations don't run in isolation; they interact with storage systems, batch applications, and machine learning libraries. Therefore, the notion of continuous applications--in contrast to batch processing--emerged, and basically means the composite of batch processing and real-time stream processing with a clear focus of the streaming part being the main driver of the application, and just accessing the data created or processed by batch processes for further augmentation. Continuous applications never stop and continuously produce data as new data arrives.