[SAMZA-300] Track producers and consumers of streams

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Martin Kleppmann
• Created: 19/Jun/14 18:39
• Updated: 28/Mar/15 00:16

Description

Each Samza job runs independently, which has a lot of advantages. However, there are situations in which it would be valuable to have a global overview of the data flows between jobs. For example:

• It's important for correctness that only one job ever publishes to a given checkpoint or changelog stream — if several jobs publish to the same stream, the result is nonsensical. However, we currently have no way of enforcing that. It would be good if a job could take a "write lock" on a stream, and thus prevent others from writing to it.
• It would be awesome to have a dashboard/visualization that graphically shows the job graph, and visually highlights the health of a job (e.g. whether a job is fallen behind).
• The job graph would also be generally useful for tracking data provenance (finding consumers who would be affected by a schema change, finding the team that is responsible for producing a particular stream, etc)
• Potentially could include additional metadata about streams, e.g. owner, serialization format, schema, documentation of semantics of the data, etc. (HCatalog for streams?)

One possibility would be for Kafka to add some of this functionality, although it may also make sense to implement it in Samza (that way it would be available for non-Kafka systems as well, and could use knowledge about the job that Samza has, but Kafka hasn't).

This is just a vague description to start a discussion. Please comment with your ideas on how to best implement this.

Issue Links

• is related to: SAMZA-73 Add topologies to Samza