REST client message metadata that can be intercepted in ClientRequestFilter

[lmartella1]

Hello,
In my Quarkus application, which exposes REST APIs and makes various client calls to external APIs as part of processing incoming requests, I need to pass metadata programmatically on each message sent via either REST or SOAP clients.

These clients can be of different types:

• Blocking REST client calls using quarkus-rest-client
• Non-blocking REST client calls using quarkus-rest-client with either Mutiny or CompletionStage
• Blocking or non-blocking SOAP client calls using quarkus-cxf

This metadata will be intercepted by a ClientRequestFilter to properly populate an HTTP header with the injected value.

Can you suggest the best technical solution to properly implement this use case, considering the mix of REST client types we need to handle?

We have already evaluated the following solutions:

• ThreadLocals, which we found unsuitable for reactive operations.
• ContextLocals, which, unlike ThreadLocals, ensure that data created within one context does not interfere with the handling of other requests. Our approach, in that case, involves storing per-client metadata in a ContextLocals before performing the client call. A ClientRequestFilter will then retrieve the metadata from the ContextLocals, remove it, and populate the outgoing header value accordingly.

Our concern with using ContextLocals is whether asynchronous clients might interfere with others executing in the same context as part of the same request processing. Do you have any precious comment to share in that front? Do you have any other options to suggest to implement this use case?

Thank you in advance.

[quarkus-bot[bot]]

/cc @cescoffier (rest-client), @geoand (rest-client)

[geoand]

ContextLocal is the way to go - Quarkus uses them extensively in its codebase