Feign 11 Proposed Roadmap

Roadmap

Making API clients easier

Response Caching
- Support caching of api responses. Allow for user's to define under what conditions a response is eligible for caching and what type of caching mechanism should be used.
- Support in-memory caching and external cache implementations (EhCache, Google, Spring, etc...)
Complete URI Template expression support
- Support level 1 through level 4 URI template expressions.
- Use URI Templates TCK to verify compliance.
Logger API refactor
- Refactor the Logger API to adhere closer to frameworks like SLF4J providing a common mental model for logging within Feign. This model will be used by Feign itself throughout and provide clearer direction on how the Logger will be used.
Retry API refactor
- Refactor the Retry API to support user-supplied conditions and better control over back-off policies.

Metric API
- Provide a first-class Metrics API that user's can tap into to gain insight into the request/response lifecycle. Possibly provide better OpenTracing support.
Async execution support via CompletableFuture
- Allow for Future chaining and executor management for the request/response lifecycle. Implementation will likely require non-backward-compatible breaking changes. However this feature is required before Reactive execution can be considered.
Reactive execution support via Reactive Streams
- For JDK 9+, consider a native implementation that uses java.util.concurrent.Flow.
- Support for Project Reactor and RxJava 2+ implementations on JDK 8.

Additional Circuit Breaker Support.
- Support additional Circuit Breaker implementations like Resilience4J and Spring Circuit Breaker