Generic Callouts

[ripienaar]

Proposed change

On the back of success with Auth Callouts we should look at a framework for generic callouts to be placed in various other scenarios:

• Place a gateway controller in-front of a subject space like $JS.API.> where the controller might pass requests through a policy engine or schema validation before passing them to JetStream
• Place a controller in the import/export point between accounts so that the exporter can asset that only well formed (those matching a schema) should pass over the export
• Selecting messages off streams as described in Expand Consumer Groups #6554

We may focus at first on request-reply scenarios as, in those scenarios, ordering guarantees are a bit relaxed. However to be clear in no case may we break the core promises of we already have around ordering.

Use case

Expansion of our security, schema and visibility initiatives. Feels to me like something to do after #6554

Contribution

No response

[RedShift1]

If I may add my 2 cents, if these callouts are developed, please make them more straightforward... I can barely wrap my head around the auth callout, the JWT inside a JWT and NKey stuff is making my WTF/minute counter explode. Perhaps also add the posibility of doing the callouts out-of-band (via HTTP for example) to make attacks on the callout infrastructure impossible.