New Sample showing Multiple Readers from different reader groups

[elizabethbain]

This sample is meant to show the behavior of Pravega when there are multiple readers on the same stream where the readers are from different reader groups. This is to be contrasted with the sample showing multiple readers on the same stream from the same reader group. In this case, the readers are reading the same segments. Current samples we have show only one writer and one reader to a stream. This sample and sample 2 is to illustrate the simple interactions and behavior of Pravega when there are multiple readers of the same data.
Scenario

1. A writer is writing to a given stream (“concurrentstream”) with specific events.
2. Two reader groups are created with one reader assigned to each.
3. Two readers (Reader A and Reader B) are started for reading from the “concurrentstream” stream.
4. Each reader writes the data to stdout with its id appended to it to identify which reader put out the data.
5. The output should demonstrate that each event is seen by both ReaderA and ReaderB. It also shows that the ordering of the data is the same across both of the readers