glm-5.2
398e3d512d
The 'WebTransport proxy' concept was conflating two distinct things; this pass separates them: 1. In-process ALPN-stream-proxy (ADR-040, in alknet-http): the h3 handler hands a WebTransport stream to another ALPN handler (SshAdapter, GitAdapter, etc.) as a Connection, so a browser with a WASM parser can reach any ALPN service via WebTransport. Path-based routing (the CONNECT path declares the target: /alknet/ssh -> SshAdapter). HttpAdapter gains Arc<HandlerRegistry> for the lookup. The browser's WASM parser implements BiStream (ADR-007) over the WebTransport stream. SSH-over-WebTransport is HTTPS-shaped at the network layer (anti-censorship: the 'VPN-like without being a VPN' use case on a clean foundation). russh-sftp demonstrates WASM targeting is feasible; SSH is the next target. 2. Standalone relay service (OQ-38, future alknet-relay crate): a full relay - fork of iroh-relay - with WebTransport proxy fallback for NAT traversal. This is infrastructure, not a mode of the h3 handler. OQ-38 reframed to be the standalone-relay scope question (distinct from the in-process proxy now resolved by ADR-040). webtransport.md updated: three stream destinations (call protocol, ALPN-handler proxy, other sub-protocols) with path-based routing; new 'ALPN-stream-proxy' section covering the WASM client side, auth model (bearer token gates the session; protocol's own auth gates the protocol session), and the HandlerRegistry reference. README/overview ADR tables and OQ summaries updated for ADR-040.
244 lines
13 KiB
Markdown
244 lines
13 KiB
Markdown
---
|
|
status: draft
|
|
last_updated: 2026-06-29
|
|
---
|
|
|
|
# alknet-http — Overview
|
|
|
|
The HTTP interface crate: serves inbound HTTP on standard ALPNs and hosts
|
|
the HTTP-backed call-protocol adapters. This document covers the crate's
|
|
two roles, its dependency edges, and the adapter location map. Component
|
|
details are in the sibling documents.
|
|
|
|
## What
|
|
|
|
`alknet-http` is the HTTP protocol handler for the ALPN-as-service
|
|
architecture. It serves two roles in one crate:
|
|
|
|
1. **HTTP server** — a `ProtocolHandler` (`HttpAdapter`) that accepts
|
|
HTTP/2, HTTP/1.1, and HTTP/3 (WebTransport) connections on the
|
|
standard IANA ALPNs (`h2`, `http/1.1`, `h3`). It serves REST APIs, the
|
|
`to_openapi`/`to_mcp` projections of local call-protocol operations,
|
|
the `/healthz` operational endpoint, and the decoy surface for
|
|
stealth mode.
|
|
2. **HTTP client host** — the home of the HTTP-transport-backed call
|
|
adapters: `from_openapi` (import external HTTP APIs as call
|
|
operations, using `reqwest` for outbound calls) and `from_mcp` (import
|
|
remote MCP tools over streamable HTTP, using `reqwest`). The reverse
|
|
projections `to_openapi` (generate an OpenAPI doc from the local
|
|
registry's `External` operations) and `to_mcp` (expose local ops as
|
|
MCP tools over streamable HTTP, using `axum`) also live here.
|
|
|
|
Both directions share the same HTTP dependencies (`axum` for serving,
|
|
`reqwest` for calling out), which is why they live in one crate rather
|
|
than being split into a server crate and a client crate. See
|
|
[ADR-039](../../decisions/039-http-server-and-client-host-colocated.md)
|
|
for the full rationale.
|
|
|
|
## Why
|
|
|
|
The crate's purpose is to be the HTTP interface library for downstream
|
|
crates that need to expose an HTTP interface. A downstream consumer (the
|
|
CLI binary, a hub deployment, a browser-facing service) wires
|
|
`HttpAdapter` into the `HandlerRegistry` for the standard HTTP ALPNs and
|
|
gets a full HTTP surface: REST projection of the call protocol, OpenAPI
|
|
discovery, MCP tool exposure, and WebTransport for browsers.
|
|
|
|
The key architectural insight that shapes the crate: **HTTP is both a
|
|
server surface and a client transport for adapters.** The server side
|
|
serves HTTP to external clients (browsers, curl, axios); the client side
|
|
makes outbound HTTP calls to external APIs (OpenAI, Anthropic, vast.ai)
|
|
through the `from_openapi`/`from_mcp` forwarding handlers. Both
|
|
directions share HTTP dependencies and HTTP-specific concerns (TLS,
|
|
headers, streaming, SSE), so they belong in one crate. See
|
|
[ADR-039](../../decisions/039-http-server-and-client-host-colocated.md)
|
|
for the colocation decision.
|
|
|
|
## Dependencies
|
|
|
|
```
|
|
alknet-http
|
|
├── alknet-core (ProtocolHandler, Connection, AuthContext, IdentityProvider, Capabilities)
|
|
├── alknet-call (OperationAdapter, OperationSpec, Handler, HandlerRegistration,
|
|
│ OperationRegistry, AdapterError, OperationProvenance)
|
|
├── axum (HTTP server — Router, extractors, middleware)
|
|
├── reqwest (HTTP client — from_openapi/from_mcp forwarding)
|
|
├── hyper (HTTP/1.1 + HTTP/2 framing; axum is built on hyper)
|
|
├── wtransport (HTTP/3 + WebTransport — feature-gated behind `h3`)
|
|
└── rmcp (MCP streamable HTTP — feature-gated behind `mcp`)
|
|
```
|
|
|
|
### The `alknet-call` dependency (ADR-003 Amendment 1)
|
|
|
|
`alknet-http` depends on `alknet-call`. ADR-003's rule is "no handler
|
|
crate depends on another handler crate," but `alknet-call` is both a
|
|
handler (it implements `ProtocolHandler` on `alknet/call`) *and* the
|
|
protocol-foundation crate that `alknet-agent`, `alknet-napi`, and now
|
|
`alknet-http` consume. `alknet-http` depending on `alknet-call` is
|
|
"HTTP uses the call protocol types" (`OperationSpec`, `Handler`,
|
|
`HandlerRegistration`, `OperationAdapter`), not "HTTP depends on SSH."
|
|
See [ADR-003 Amendment 1](../../decisions/003-crate-decomposition.md).
|
|
|
|
`alknet-call` stays lean — it has no `reqwest`, no `axum`, no HTTP
|
|
dependencies. The `from_openapi`/`from_mcp` forwarding handlers are
|
|
opaque `Arc<dyn Handler>` from the registry's perspective: constructed by
|
|
`alknet_http::from_openapi()` at registration time, stored in
|
|
`HandlerRegistration`, dispatched by the `CallAdapter` which doesn't
|
|
know `reqwest` is involved.
|
|
|
|
## ALPNs
|
|
|
|
| ALPN | Handler | Transport | Browser? |
|
|
|------|---------|-----------|----------|
|
|
| `http/1.1` | `HttpAdapter` | HTTP/1.1 over QUIC stream | No |
|
|
| `h2` | `HttpAdapter` | HTTP/2 over QUIC stream | No |
|
|
| `h3` | `HttpAdapter` | HTTP/3 / WebTransport | Yes (X.509 required) |
|
|
|
|
These are standard IANA ALPN strings, not `alknet/`-prefixed. Any HTTP
|
|
client connects without knowing about alknet — the TLS handshake
|
|
negotiates `h2` or `http/1.1` normally, and the `HttpAdapter` serves
|
|
HTTP. This is the stealth mapping (ADR-010): clients that don't offer
|
|
alknet ALPNs get the HTTP handler, just like port scanners in stealth
|
|
mode.
|
|
|
|
The `HttpAdapter` registers for all three ALPNs (when the corresponding
|
|
features are enabled). The endpoint's `HandlerRegistry` maps each ALPN to
|
|
the same `HttpAdapter` instance; the handler branches on
|
|
`connection.remote_alpn()` to pick the right framing.
|
|
|
|
## Adapter Location Map
|
|
|
|
The decomposition principle (settled in
|
|
[client-and-adapters.md](../call/client-and-adapters.md)): the adapter
|
|
trait lives where the types live (`alknet-call`); the adapter
|
|
implementations live where their transport dependencies live.
|
|
|
|
```
|
|
alknet-call (lean — no HTTP client, no HTTP server)
|
|
├── OperationAdapter trait (the contract — async, ADR-017 §5)
|
|
├── from_call (QUIC — discovers remote ops via call protocol)
|
|
├── from_jsonschema (pure parse — caller fetches the doc, passes it in)
|
|
└── CallClient (outbound connection opener)
|
|
|
|
alknet-http (owns HTTP server + HTTP client)
|
|
├── HttpAdapter (axum server — inbound HTTP on h2/http1.1/h3)
|
|
├── from_openapi (parse OpenAPI doc + reqwest forwarding handler)
|
|
├── to_openapi (generate OpenAPI doc from local registry)
|
|
├── from_mcp (feature-gated) (import remote MCP tools over streamable HTTP — reqwest)
|
|
└── to_mcp (feature-gated) (expose local ops as MCP tools over streamable HTTP — axum)
|
|
```
|
|
|
|
`alknet-call` never sees the HTTP client. The `from_openapi`/`from_mcp`
|
|
forwarding handlers are opaque `Arc<dyn Handler>` from the registry's
|
|
perspective. `alknet-call` stays lean; `alknet-http` owns both HTTP
|
|
directions.
|
|
|
|
## Feature Gates
|
|
|
|
```toml
|
|
[features]
|
|
default = ["h2", "http1"] # the non-browser HTTP surface
|
|
h3 = ["dep:wtransport"] # HTTP/3 + WebTransport (browser path; X.509 required)
|
|
mcp = ["dep:rmcp"] # from_mcp / to_mcp (streamable HTTP only — ADR-037)
|
|
```
|
|
|
|
- `h2` + `http1` (default): the `axum` + `hyper` HTTP/1.1 + HTTP/2
|
|
server. This is the surface non-browser clients use.
|
|
- `h3`: the `wtransport` (or quinn HTTP/3 extension) dependency. Adds
|
|
the `h3` ALPN handler and the WebTransport streaming path. See
|
|
[webtransport.md](webtransport.md) and
|
|
[ADR-038](../../decisions/038-http3-and-webtransport-as-first-class.md).
|
|
- `mcp`: the `rmcp` dependency with streamable HTTP transport features
|
|
only. Adds `from_mcp`/`to_mcp`. See [http-mcp.md](http-mcp.md) and
|
|
[ADR-037](../../decisions/037-mcp-stdio-transport-exclusion.md).
|
|
|
|
A deployment that only needs the REST surface (no browsers, no MCP) uses
|
|
the default features. A browser-facing hub enables `h3`. A deployment
|
|
that wants MCP tool import/export enables `mcp`.
|
|
|
|
## The No-Env-Vars Invariant
|
|
|
|
The `from_openapi`/`from_mcp` forwarding handlers are the **credential
|
|
injection point** for the no-env-vars architecture. The path (from the
|
|
gap analysis):
|
|
|
|
```
|
|
vault → assembly layer → Capabilities → HandlerRegistration.capabilities
|
|
→ OperationContext.capabilities → from_openapi handler reads
|
|
context.capabilities.get("openai") → injects into HTTP Authorization
|
|
header → reqwest request goes out with vault-derived credential
|
|
```
|
|
|
|
This makes aisdk's `std::env::var("OPENAI_API_KEY")` reads unreachable —
|
|
the assembly layer never calls `Default::default()` on a provider; it
|
|
constructs them with vault-derived credentials, or routes HTTP calls
|
|
through `from_openapi` operations that carry the credential in
|
|
`Capabilities`.
|
|
|
|
**This is a spec-level invariant**: no handler reads outbound
|
|
credentials from any source other than `OperationContext.capabilities`.
|
|
The `from_openapi`/`from_mcp` implementations in `alknet-http` are
|
|
verified against this invariant. See ADR-014 and
|
|
[client-and-adapters.md](../call/client-and-adapters.md).
|
|
|
|
## Architecture (component pointers)
|
|
|
|
- **[http-server.md](http-server.md)** — the `HttpAdapter` for `h2`/
|
|
`http/1.1`: how axum is run over a QUIC bidirectional stream, Bearer
|
|
auth resolution, the `/healthz` raw route, stealth decoy, and the
|
|
HTTP-to-call dispatch (ADR-036).
|
|
- **[http-adapters.md](http-adapters.md)** — `from_openapi` (parse
|
|
OpenAPI, build forwarding handlers with `reqwest`) and `to_openapi`
|
|
(generate an OpenAPI doc from the registry's `External` operations).
|
|
Error fidelity per ADR-023.
|
|
- **[http-mcp.md](http-mcp.md)** — `from_mcp`/`to_mcp` (feature-gated),
|
|
streamable HTTP only (ADR-037), the rmcp integration.
|
|
- **[webtransport.md](webtransport.md)** — the `h3` ALPN handler,
|
|
WebTransport session/stream handling, the browser streaming path
|
|
(ADR-038).
|
|
|
|
## Design Decisions
|
|
|
|
| Decision | ADR | Summary |
|
|
|----------|-----|---------|
|
|
| HTTP-to-call operation mapping | [ADR-036](../../decisions/036-http-to-call-operation-mapping.md) | Direct path mapping; `to_openapi` is projection, not router |
|
|
| MCP stdio transport exclusion | [ADR-037](../../decisions/037-mcp-stdio-transport-exclusion.md) | Streamable HTTP only; stdio is not built (RCE vector) |
|
|
| HTTP/3 + WebTransport first-class | [ADR-038](../../decisions/038-http3-and-webtransport-as-first-class.md) | `h3` in scope, not deferred; browser streaming uses QUIC streams |
|
|
| HTTP server + client host colocated | [ADR-039](../../decisions/039-http-server-and-client-host-colocated.md) | One crate for server + adapters (shared HTTP deps, shared mapping) |
|
|
| WebTransport ALPN-stream-proxy | [ADR-040](../../decisions/040-webtransport-alpn-stream-proxy.md) | Browser → WebTransport stream → any ALPN handler (SSH, git, SFTP) via WASM parser |
|
|
| `alknet-call` is protocol-foundation | [ADR-003](../../decisions/003-crate-decomposition.md) Am. 1 | `alknet-http` depends on `alknet-call` (types, not peer handler) |
|
|
| Bearer auth via `resolve_from_token` | [ADR-004](../../decisions/004-auth-as-shared-core.md) | HTTP handler credential source + resolution (settled) |
|
|
| Stealth mode = HTTP handler on standard ALPNs | [ADR-010](../../decisions/010-alpn-router-and-endpoint.md) | Decoy for unknown paths (settled) |
|
|
| Adapter-registered ops are `Internal` | [ADR-015](../../decisions/015-privilege-model-and-authority-context.md) | `from_openapi`/`from_mcp` produce `Internal` leaves (settled) |
|
|
| `OperationAdapter` trait is async | [ADR-017](../../decisions/017-call-protocol-client-and-adapter-contract.md) | HTTP adapters implement the async trait (settled) |
|
|
| `to_*` adapters are projections | [ADR-017](../../decisions/017-call-protocol-client-and-adapter-contract.md) | `to_openapi`/`to_mcp` consume the registry, don't produce entries (settled) |
|
|
| Error schema fidelity | [ADR-023](../../decisions/023-operation-error-schemas.md) | `from_openapi` maps HTTP status → `HTTP_<status>` codes; `to_openapi` projects back (settled) |
|
|
| Browsers require X.509 | [ADR-027](../../decisions/027-tls-identity-redesign-acme-rawkey-decoupling.md) | `h3`/WebTransport needs X.509 (settled) |
|
|
| Browsers are not alknet peers | [ADR-034](../../decisions/034-outgoing-only-x509-and-three-peer-roles.md) | Browser over WebTransport/HTTPS = bearer token, no `PeerId` (settled) |
|
|
|
|
## Open Questions
|
|
|
|
See [open-questions.md](../../open-questions.md) for full details.
|
|
|
|
- **OQ-13** (resolved): Operation path format `/{service}/{op}` — the
|
|
HTTP path.
|
|
- **OQ-26** (resolved): `AdapterError` variants — reused by HTTP
|
|
adapters; `#[non_exhaustive]` allows extension.
|
|
- **OQ-37** (resolved): Browsers are not peers; `h3` hub is a
|
|
mixed-fingerprint `PeerEntry`.
|
|
- **OQ-38** (open, scope): WebTransport relay-as-proxy — does the proxy
|
|
live in `alknet-http` or a separate relay crate?
|
|
- **OQ-39** (open): `to_openapi` published-spec versioning — versioning
|
|
strategy for generated OpenAPI specs.
|
|
- **OQ-40** (open): reqwest client config and connection pooling —
|
|
two-way-door config shape.
|
|
|
|
## References
|
|
|
|
- `docs/research/alknet-http/phase-0-findings.md` — Phase 0 research
|
|
- `docs/research/alknet-call-completion/gap-analysis.md` — adapter
|
|
location map, no-env-vars invariant
|
|
- `/workspace/@alkdev/operations/src/from_openapi.ts`,
|
|
`/workspace/@alkdev/operations/src/from_mcp.ts` — TypeScript prior art
|
|
- `/workspace/rust-sdk/` — MCP Rust SDK (rmcp); streamable HTTP examples
|
|
- `/workspace/wtransport/` — pure-Rust WebTransport reference |