PuduLangMediator.Open

type: module path: "@root/src/PuduLangMediator/Open.pudu" fidelity: Active grammar: "[[grammar/pudu]]" depth_score: 0.6 depth_status: MEDIUM tags: [module, seam] aliases: [PuduLangMediator.Open]

Purpose

Components that apply to every kind: open behaviors, pre-processors, post-processors, exception actions, notification handlers, and stream behaviors, each a trait whose one member is generic over the message types.

Interface

Signatures

export trait Behavior {
  fn handleRequest[Q, R, E](self: &Self, request: &Q, info: &Message.Info, context: Context.Context, next: Request.Next[R, E]) -> Messaging.Outcome[R, E]
}

export trait PreProcessor {
  fn beforeRequest[Q, E](self: &Self, request: &Q, info: &Message.Info, context: Context.Context) -> Messaging.Outcome[(), E]
}

export trait PostProcessor {
  fn afterRequest[Q, R, E](self: &Self, request: &Q, response: &R, info: &Message.Info, context: Context.Context) -> Messaging.Outcome[(), E]
}

export trait ExceptionAction {
  fn onFailure[Q, E](self: &Self, request: &Q, failure: &Messaging.Failure[E], info: &Message.Info, context: Context.Context) -> ()
}

export trait NotificationHandler {
  fn handleNotification[N, E](self: &Self, notification: &N, info: &Message.Info, context: Context.Context) -> Messaging.Outcome[(), E]
}

export trait StreamBehavior {
  fn handleStream[Q, T, E](self: &Self, request: &Q, info: &Message.Info, context: Context.Context, sink: Stream.Sink[T], next: Stream.Next[T, E]) -> Messaging.Outcome[(), E]
}

export type Listener = { name: Str, handler: dynamic NotificationHandler }

Linkage

• Requires: [[src/PuduLangMediator]], [[src/PuduLangMediator/Context]], [[src/PuduLangMediator/Message]], [[src/PuduLangMediator/Request]], [[src/PuduLangMediator/Stream]].
• Consumed by: [[src/PuduLangMediator/Behaviors/Logging]], [[src/PuduLangMediator/Catalog]], [[src/PuduLangMediator/Compose]], [[src/PuduLangMediator/Registration]].

Algorithm

1. A program implements a trait for its own type and registers a value of it; the mediator holds it as dynamic and calls it for every kind in its layer.
2. Each trait's member has its own name, so one type may implement every trait.

Negative Logic (Prohibited Paths)

• An open component cannot build a value of R or an error E; it runs next, answers what next answered, or refuses.

Edge Cases

• An open component reads the kind's Info and tags to decide whether to act.

Depth

DEPTH 0.6 (MEDIUM). Tested by the suite mirroring this module under test/.

Grill Log

• Q: Why traits with generic members instead of closures? A: A closure value has one type; a component that applies to every kind must be generic in the request, response, and error types, which only a trait member can be. _Rejected:_ closures over an erased view (every component would unpack and repack values).
• Q: Why distinct member names across the traits? A: One type implementing two traits with the same member name is ambiguous where it is widened; distinct names let one recorder log requests, streams, and notifications. _Rejected:_ one handle member per trait.

Referenced by

[[CHANGELOG]] · [[seams/Open]] · [[src/PuduLangMediator]] · [[src/PuduLangMediator/Behaviors/Logging]] · [[src/PuduLangMediator/Catalog]] · [[src/PuduLangMediator/Compose]] · [[src/PuduLangMediator/Context]] · [[src/PuduLangMediator/Message]] · [[src/PuduLangMediator/Registration]] · [[src/PuduLangMediator/Request]] · [[src/PuduLangMediator/Stream]] · [[src/PuduLangMediator/_MOC]]