Designing a Spark Streaming application
Building a real-time application differs from batch processing in terms of architecture and components involved. While the latter can easily be built bottom-up, where programmers add functionalities and components when needed, the former usually needs to be built top-down with a solid architecture in place. In fact, due to the constraints of volume and velocity (or veracity in a streaming context), an inadequate architecture will prevent programmers from adding new functionalities. One always needs a clear understanding of how streams of data are interconnected, how and where they are processed, cached, and retrieved.
A tale of two architectures
In terms of stream processing using Apache Spark, there are two ...