NoSQL support

[smarie16]

NoSQL support (Single-Document Outbox pattern)

Currently, namastack-outbox provides excellent support for relational databases via the JPA and JDBC modules. However, in many modern distributed systems using NoSQL (like MongoDB, Opensearch, or DynamoDB), the implementation of the Transactional Outbox pattern differs significantly.

In a relational setup, we use a separate table for messages. In a NoSQL setup, to maintain atomicity without multi-document transactions, the outbox is typically implemented as a property or an array directly within the database record (document/item).

I would like to know if NoSQL support is on the project roadmap. Specifically, support for storing pending events as an attribute within the business document to ensure atomic writes.

I believe adding this would make namastack-outbox the go-to library for both SQL and NoSQL event-driven architectures in the Spring/Java ecosystem.

[rolandbeisel]

Thank you for opening this issue and for your interest in namastack-outbox!

You're absolutely right that NoSQL databases require a different approach to the Transactional Outbox pattern.
NoSQL support is not currently implemented, but it's a valuable addition worth considering for the project roadmap.

Each NoSQL database has different guarantees (MongoDB single-document atomicity, DynamoDB conditional writes, etc.). The current abstraction assumes a separate persistence store for outbox messages. Supporting embedded outbox properties would require a different persistence module interface. Embedded messages need different polling strategies compared to querying a dedicated table

Would likely need separate modules for each NoSQL database (e.g., namastack-outbox-mongodb, namastack-outbox-dynamodb)

This would indeed broaden namastack-outbox's applicability. We recognize the value this would bring to namastack-outbox and will think about how we could support this in future.

[smarie16]

Thank you the quality of the answer

Let me know if you're taking this on! I'm happy to jump in and help with the design or the build.