Test, understand, document library behaviour on query exceptions and other error scenarios

[hartmut-co-uk]

I want to know how the library / kstreams app behaves throughout the entire lifecycle when interaction with cassandra fails (Exception thrown, ...). Data loss through events being missed/skipped should be avoided. Data inconsistency (retries of non-idempotent processing logic) issues should be understood & documented. Also patterns on how to handle exceptions as part of the application code should be defined + documented.

Initial brainstorming of possible scenarios:

• query exception/error for writes
• query exception/error for reads
• cluster unavailable
• write blocked, cluster consistency cannot be fulfilled
• writing data fails (no MODIFY permission)
• creating tables fails (no CREATE permission)

### Tasks

• manual test, debugging, analysis
• write unit tests
• write documentation
• task out further / create follow-up issues