Full-surface integration suite (tests/full_surface.rs, mcp feature): - one HttpAdapter over real TCP (ProtocolHandler::handle path) serving gateway endpoints, /openapi.json, /mcp, and the WS channels session - gateway: search/schema/call/subscribe/batch/publish presence, envelope shapes, error fidelity end-to-end - from_openapi import -> Internal-by-default invisible from the wire -> External facade composes it via env.invoke -> upstream HTTP API called end-to-end (ADR-015 composition model exercised) - to_openapi 6-path doc validated against openapiv3 over the wire - to_mcp: MCP client connects to /mcp on the served adapter, lists the 4 gateway tools, search returns ACL-filtered ops (Sub excluded) Production fix: the WS upgrade route was reserved but never wired into HttpAdapter's router (the ws-upgrade-session tests built their own router). Now wired with ws_bearer_auth (401 without a resolvable token) around ws_upgrade_handler. Docs sync: all 28 'Port notes' sections/blockquotes stripped from ported ADRs/specs; OQ-01/OQ-02 statuses corrected to resolved in overview.md, websocket.md, and the README table (open-questions.md was already current). Publish prep: cargo publish --dry-run --allow-dirty succeeds; cargo doc --no-deps warning-free (ADR link targets fixed); feature combinations (default / test-support / mcp / wss / all) compile warning-free under clippy -D warnings. Verified: cargo test (182 lib default), --all-features (227 lib + 29 integration), clippy -D warnings x3 feature sets, fmt, doc, publish --dry-run.
71 lines
4.7 KiB
Markdown
71 lines
4.7 KiB
Markdown
# ADR-002: ProtocolHandler Trait
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*Ported from alknet ADR-002 (ProtocolHandler Trait); re-targeted to alkhttp.*
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## Status
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Accepted
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## Context
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The previous architecture had two separate interface traits: `StreamInterface` (for byte-stream protocols like SSH, raw TCP) and `MessageInterface` (for message-based protocols like DNS, HTTP). This split created complexity — each interface type needed its own listener configuration, its own dispatch path, and its own framing assumptions. The `ListenerConfig` enum had three variants. The server accept loop handled three different listener types.
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In practice, the distinction between "stream" and "message" protocols is artificial at the handler level. SSH starts as a byte stream but internally multiplexes channels and messages. DNS over QUIC is message-based but arrives as a stream of frames. HTTP/2 is both — bidirectional streams with message semantics. Every protocol can be modeled as "receive a byte stream, manage your own wire format."
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iroh's `ProtocolHandler` trait demonstrates this: it takes a bidirectional stream and the handler is responsible for its own protocol. One trait, one dispatch point.
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## Decision
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A single `ProtocolHandler` trait replaces both `StreamInterface` and `MessageInterface`:
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> **Note**: The signature below was revised by ADR-007. The `handle()` method
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> now receives a `Connection` (not a `BiStream`) — see ADR-007 for the
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> current authoritative signature (see the alkcall crate docs). The original
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> signature is retained here for historical context.
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```rust
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#[async_trait]
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pub trait ProtocolHandler: Send + Sync + 'static {
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/// The ALPN string this handler claims (e.g. b"alknet/ssh")
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fn alpn(&self) -> &'static [u8];
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/// Handle an incoming connection (revised by ADR-007 to receive
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/// `Connection` instead of `BiStream`)
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async fn handle(&self, connection: Connection, auth: &AuthContext) -> Result<(), HandlerError>;
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}
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```
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- `alpn()` returns a static byte string — the handler's ALPN identifier
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- `handle()` receives a `Connection` (revised by ADR-007 from the original
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`BiStream`) and an `AuthContext` carrying the authenticated identity, and
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returns `HandlerError` on failure
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- Every handler manages its own wire format — no shared framing, no StreamInterface/MessageInterface split
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- The `ListenerConfig` enum is eliminated — ALPN advertisement configuration replaces it
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**AuthContext resolution is hybrid** (see ADR-004, OQ-02 resolution): the endpoint resolves what it can before calling `handle()` (e.g., TLS client certificate fingerprint), and the handler resolves what it must inside `handle()` (e.g., AuthToken in the first frame of a call stream). The `AuthContext` passed to `handle()` may contain partial identity information — the handler is responsible for completing authentication if the endpoint didn't have enough information.
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In alkhttp, the `HttpAdapter` implements this trait on the standard HTTP ALPNs (`h2`, `http/1.1`): it accepts one bidirectional stream (BiStream) yielded by `Connection::accept_bi()`, serves the HTTP/1.1 + HTTP/2 surface over it, and extracts the Bearer credential for auth resolution.
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## Consequences
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**Positive:**
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- One trait, one dispatch point — eliminates the StreamInterface/MessageInterface split and ListenerConfig enum
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- Each handler owns its wire format — no shared framing assumptions that constrain protocol design
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- Adding a new protocol is implementing one trait with two methods
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- Testable in isolation — give a handler a mock BiStream and AuthContext
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- WASM-compatible in principle — handlers that don't need tokio runtime features compile to WASM
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**Negative:**
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- Every handler must implement its own framing — no shared "read a length-prefixed message" utility (mitigated: common utilities can live in `alkcall` without mandating their use)
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- Handlers that want message semantics must build them (mitigated: the call protocol provides this as a handler, not a mandatory layer)
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- AuthContext resolution is hybrid — the endpoint resolves what it can (TLS-level auth), but handlers that need protocol-level credential extraction must do so inside handle(). This means AuthContext may be partial when handle() is called. Handlers must not assume AuthContext is fully resolved.
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## References
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- Pivot proposal (alknet mono-repo): `docs/research/pivot/alpn-service-architecture.md`
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- [ADR-001](001-alpn-protocol-dispatch.md): ALPN-based protocol dispatch
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- [ADR-004](004-auth-as-shared-core.md): Auth as shared core (IdentityProvider)
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- ADR-007: BiStream type definition — revised this ADR's signature from BiStream to Connection (see the alkcall crate docs)
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- iroh ProtocolHandler pattern (alknet mono-repo): `docs/research/references/iroh/`
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- Replaces StreamInterface, MessageInterface, and ListenerConfig
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