Major Description
A need with stream processing is to want to re-process prior messages at some later date. An example of this is having a stream processing job that is classifying messages in some way using a machine learning algorithm. At some point, the algorithm will be updated with a more accurate vector of weights. When this happens, usually you wish to re-process past messages to get more accurate results. Usually this is solved by running a parallel pipeline from Hadoop.
We have thought extensively about this use case, and should document how to use Samza in a re-processing use case.