stella-ops.org/git.stella-ops.org
1
0
Fork 0
Code Issues Pull Requests Actions 16 Releases Wiki Activity
Files
6d049905c7673685b19a16b56b3635dd248a30a9
git.stella-ops.org/docs/router/implplan.md
master 0c9e8d5d18 router planning
2025-12-02 18:38:32 +02:00

10 KiB
Raw Blame History

Start by treating docs/router/specs.md as law. Nothing gets coded that contradicts it. The first sprint or two should be about wiring the skeleton and proving the core flows with the simplest possible transport, then layering in the real transports and migration paths.

I’d structure the work for your agents like this.

0. Read & freeze invariants

All agents:

  • Read docs/router/specs.md end to end.

  • Extract and pin the non-negotiables:

    • Method + Path identity.
    • Strict semver for versions.
    • Region from GatewayNodeConfig.Region (no host/header magic).
    • No HTTP transport for microservice communications.
    • Single connection carrying HELLO + HEARTBEAT + REQUEST/RESPONSE + CANCEL.
    • Router treats body as opaque bytes/streams.
    • RequiringClaims replaces any form of AllowedRoles.

Agree that these are invariants; any future idea that violates them needs an explicit spec change first.

1. Lay down the solution skeleton

“Skeleton” agent (or gateway core agent):

Create the basic project structure, no logic yet:

  • src/__Libraries/StellaOps.Router.Common
  • src/__Libraries/StellaOps.Router.Config
  • src/__Libraries/StellaOps.Microservice
  • src/StellaOps.Gateway.WebService
  • docs/router/ already has specs.md (add placeholders for the other docs).

Goal: everything builds, but most classes are empty or stubs.

2. Implement the shared core model (Common)

Common/core agent:

Implement only the data and interfaces, no behavior:

  • Enums:

    • TransportType, FrameType, InstanceHealthStatus.

  • Models:

    • ClaimRequirement
    • EndpointDescriptor
    • InstanceDescriptor
    • ConnectionState
    • RoutingContext, RoutingDecision
    • PayloadLimits

  • Interfaces:

    • IGlobalRoutingState
    • IRoutingPlugin
    • ITransportServer
    • ITransportClient

  • Frame struct/class:

    • FrameType, CorrelationId, Payload (byte[]).

Leave implementations of IGlobalRoutingState, IRoutingPlugin, transports, etc., for later steps.

Deliverable: a stable set of contracts that gateway + microservice SDK depend on.

3. Build a fake “in-memory” transport plugin

Transport agent:

Before UDP/TCP/Rabbit, build an in-process transport:

  • InMemoryTransportServer and InMemoryTransportClient.
  • They share a concurrent dictionary keyed by ConnectionId.
  • Frames are passed via channels/queues in memory.

Purpose:

  • Let you prove HELLO/HEARTBEAT/REQUEST/RESPONSE/CANCEL semantics and routing logic without dealing with sockets and Rabbit yet.
  • Let you unit and integration test the router and SDK quickly.

This plugin will never ship to production; it’s only for dev tests and CI.

4. Microservice SDK: minimal handshake & dispatch (with InMemory)

Microservice agent:

Initial focus: “connect and say HELLO, then handle a simple request.”

  1. Implement StellaMicroserviceOptions.

  2. Implement AddStellaMicroservice(...):

    • Bind options.
    • Register endpoint handlers and SDK internal services.

  3. Endpoint discovery:

    • Implement runtime reflection for [StellaEndpoint] + handler types.
    • Build in-memory EndpointDescriptor list (simple: no YAML yet).

  4. Connection:

    • Use InMemoryTransportClient to “connect” to a fake router.

    • On connect, send a HELLO frame with:

      • Identity.
      • Endpoint list and metadata (SupportsStreaming false for now, simple RequiringClaims empty).

  5. Request handling:

    • Implement IRawStellaEndpoint and adapter to it.

    • Implement RawRequestContext / RawResponse.

    • Implement a dispatcher that:

      • Receives Request frame.
      • Builds RawRequestContext.
      • Invokes the correct handler.
      • Sends Response frame.

Do not handle streaming or cancellation yet; just basic request/response with small bodies.

5. Gateway: minimal routing using InMemory plugin

Gateway agent:

Goal: HTTP → in-memory transport → microservice → HTTP response.

  1. Implement GatewayNodeConfig and bind it from config.

  2. Implement IGlobalRoutingState as a simple in-memory implementation that:

    • Holds ConnectionState objects.
    • Builds a map (Method, Path) → endpoint + connections.

  3. Implement a minimal IRoutingPlugin that:

    • For now, just picks any connection that has the endpoint (no region/ping logic yet).

  4. Implement minimal HTTP pipeline:

    • EndpointResolutionMiddleware:

      • (Method, Path) → EndpointDescriptor from IGlobalRoutingState.

    • Naive authorization middleware stub (only checks “needs authenticated user”; ignore real requiringClaims for now).

    • RoutingDecisionMiddleware:

      • Ask IRoutingPlugin for a RoutingDecision.

    • TransportDispatchMiddleware:

      • Build a Request frame.
      • Use InMemoryTransportClient to send and await Response.
      • Map response to HTTP.

  5. Implement HELLO handler on gateway side:

    • When InMemory “connection” from microservice appears and sends HELLO:

      • Construct ConnectionState.
      • Update IGlobalRoutingState with endpoint → connection mapping.

Once this works, you have end-to-end:

  • Example microservice.
  • Example gateway.
  • In-memory transport.
  • A couple of test endpoints returning simple JSON.

6. Add heartbeat, health, and basic routing rules

Common/core + gateway agent:

Now enforce liveness and basic routing:

  1. Heartbeat:

    • Microservice SDK sends HEARTBEAT frames on a timer.
    • Gateway updates LastHeartbeatUtc and Status.

  2. Health:

    • Add background job in gateway that:

      • Marks instances Unhealthy if heartbeat stale.

  3. Routing:

    • Enhance IRoutingPlugin to:

      • Filter out Unhealthy instances.
      • Prefer gateway region (using GatewayNodeConfig.Region).
      • Use simple AveragePingMs stub from request/response timings.

Still using InMemory transport; just building the selection logic.

7. Add cancellation semantics (with InMemory)

Microservice + gateway agents:

Wire up cancellation logic before touching real transports:

  1. Common:

    • Extend FrameType with Cancel.

  2. Gateway:

    • In TransportDispatchMiddleware:

      • Tie HttpContext.RequestAborted to a SendCancelAsync call.
      • On timeout, send CANCEL.

    • Ignore late Response/stream data for canceled correlation IDs.

  3. Microservice:

    • Maintain _inflight map of correlation → CancellationTokenSource.
    • When Cancel frame arrives, call cts.Cancel().
    • Ensure handlers receive and honor CancellationToken.

Prove via tests: if client disconnects, handler stops quickly.

8. Add streaming & payload limits (still InMemory)

Gateway + microservice agents:

  1. Streaming:

    • Extend InMemory transport to support RequestStreamData / ResponseStreamData frames.

    • On the gateway:

      • For SupportsStreaming endpoints, pipe HTTP body stream → frame stream.
      • For response, pipe frames → HTTP response stream.

    • On microservice:

      • Expose RawRequestContext.Body as a stream reading frames as they arrive.
      • Allow RawResponse.WriteBodyAsync to stream out.

  2. Payload limits:

    • Implement PayloadLimits enforcement at gateway:

      • Early reject large Content-Length.
      • Track counters in streaming; trigger cancellation when exceeding thresholds.

Demonstrate with a fake “upload” endpoint that uses IRawStellaEndpoint and streaming.

9. Implement real transport plugins one by one

Transport agent:

Now replace InMemory with real transports:

Order:

  1. TCP plugin (easiest baseline):

    • Length-prefixed frame protocol.
    • Connection per microservice instance (or multi-instance if needed later).
    • Implement HELLO/HEARTBEAT/REQUEST/RESPONSE/STREAM/CANCEL as per frame model.

  2. Certificate (TLS) plugin:

    • Wrap TCP plugin with TLS.
    • Add configuration for server & client certs.

  3. UDP plugin:

    • Single datagram = single frame; no streaming.
    • Enforce MaxRequestBytesPerCall.
    • Use for small, idempotent operations.

  4. RabbitMQ plugin:

    • Add exchanges/queues for HELLO/HEARTBEAT and REQUEST/RESPONSE.
    • Use CorrelationId properties for matching.
    • Guarantee at-most-once semantics where practical.

While each plugin is built, keep the core router and microservice SDK relying only on ITransportClient/ITransportServer abstractions.

10. Add Router.Config + Microservice YAML integration

Config agent:

  1. Implement __Libraries/StellaOps.Router.Config:

    • YAML → RouterConfig binding.
    • Services, endpoints, static instances, payload limits.
    • Hot-reload via IOptionsMonitor / file watcher.

  2. Implement microservice YAML:

    • Endpoint-level overrides only (timeouts, requiringClaims, SupportsStreaming).
    • Merge logic: code defaults → YAML override.

  3. Integrate:

    • Gateway uses RouterConfig for:

      • Defaults when no microservice registered yet.
      • Payload limits.

    • Microservice uses YAML to refine endpoint metadata before sending HELLO.

11. Build a reference example + migration skeleton

DX / migration agent:

  1. Build a StellaOps.Billing.Microservice example:

    • A couple of simple endpoints (GET/POST).
    • One streaming upload endpoint.
    • YAML for requiringClaims and timeouts.

  2. Build a StellaOps.Gateway.WebService example config around it.

  3. Document the full path:

    • How to run both locally.
    • How to add a new endpoint.
    • How cancellation behaves (killing the client, watching logs).
    • How payload limits work (try to upload too-large file).

  4. Outline migration steps from an imaginary StellaOps.Billing.WebService using the patterns in Migration of Webservices to Microservices.md.

12. Process guidance for your agents

  • Do not jump to UDP/TCP immediately. Prove the protocol (HELLO/HEARTBEAT/REQUEST/RESPONSE/STREAM/CANCEL), routing, and limits on the InMemory plugin first.

  • Guard the invariants. If someone proposes “just call HTTP between services” or “let’s derive region from host,” they’re violating spec and must update docs/router/specs.md before coding.

  • Keep Common stable. Changes to StellaOps.Router.Common must be rare and reviewed; everything else depends on it.

  • Document as you go. Every time a behavior settles (e.g. status mapping, frame layout), update the docs under docs/router/ so new agents always have a single source of truth.

If you want, next step I can convert this into a task board (epic → stories) per repo folder, so you can assign specific chunks to named agents.