Fabian Hueske and Aljoscha Krettek describe streaming versus batch processing in Apache Flink:
The Apache Flink project has followed the philosophy of taking a unified approach to batch and stream data processing, building on the core paradigm of “continuous processing of unbounded data streams” for a long time. If you think about it, carrying out offline processing of bounded data sets naturally fits the paradigm: these are just streams of recorded data that happen to end at some point in time.
Flink is not alone in this: there are other projects in the open source community that embrace “streaming first, with batch as a special case of streaming,” such as Apache Beam; and this philosophy has often been cited as a powerful way to greatly reduce the complexity of data infrastructures by building data applications that generalize across real-time and offline processing.
Check it out. At the end, the authors also describe Blink, a fork of Flink being (slowly) merged back in and which supports this paradigm.