Source PR: #420 · docs/rfcs/0027-capability-detection.md · @ryanleecode
Description
system.feature_supported answers a Method { id } query, so a product can check whether the host has a handler for a wire discriminant. Unregistered discriminants get an UNSUPPORTED_METHOD reply instead of being dropped.
Motivation
Products update continuously while native hosts update on app-release cycles, so new products routinely run against old hosts. An unknown wire ID is dropped silently today and the pending call hangs forever.
Requirements
HostFeatureSupportedRequest::Method { id }; older hosts fail to decode it and return MalformedFrame, which is the age signal.supported is computed from the dispatcher's own wire table, never a static list.- Dispatch fall-through replies
UNSUPPORTED_METHOD echoing request_id; the client rejects with CallError::Unsupported.
- Codegen exposes a
supportsMethod("<method>") helper.
Tasks
Note: RFC number 0027 is also claimed by #468.
Source PR: #420 ·
docs/rfcs/0027-capability-detection.md· @ryanleecodeDescription
system.feature_supportedanswers aMethod { id }query, so a product can check whether the host has a handler for a wire discriminant. Unregistered discriminants get anUNSUPPORTED_METHODreply instead of being dropped.Motivation
Products update continuously while native hosts update on app-release cycles, so new products routinely run against old hosts. An unknown wire ID is dropped silently today and the pending call hangs forever.
Requirements
HostFeatureSupportedRequest::Method { id }; older hosts fail to decode it and returnMalformedFrame, which is the age signal.supportedis computed from the dispatcher's own wire table, never a static list.UNSUPPORTED_METHODechoingrequest_id; the client rejects withCallError::Unsupported.supportsMethod("<method>")helper.Tasks
Note: RFC number 0027 is also claimed by #468.