# SignalRs

Custom binary SignalR protocol, client infrastructure, message tagging, and serialization helpers.

> **Architecture:** For full dispatch flow, tag system, and tech debt documentation see `AyCode.Services/docs/SIGNALR.md`.
> **Binary protocol:** For wire format, zero-copy pipeline, and dual BWO pattern see `AyCode.Services/docs/SIGNALR_BINARY_PROTOCOL.md`.

## Key Files

### Protocol
- **`AcBinaryHubProtocol.cs`** — Unsealed base `IHubProtocol` replacing JSON+Base64 with `AcBinarySerializer`. Handles all 9 SignalR message types. Uses `BufferWriterBinaryOutput` standalone mode for zero-copy writes. `byte[]`/`SignalData` fast-path bypasses serializer. `CreateByteArrayResult` virtual hook for derived protocols. Inner `SpanReader` ref struct for zero-alloc parsing.
- **`AyCodeBinaryHubProtocol.cs`** — Derived protocol. Overrides `CreateByteArrayResult` to rent from `ArrayPool` when `targetType == typeof(SignalData)`. Register this instead of `AcBinaryHubProtocol`.
- **`SignalData.cs`** — `IDisposable` wrapper for `byte[]` with optional `ArrayPool` lifecycle. `Span` for zero-copy access, `Dispose()` returns rented buffer. Created by `AyCodeBinaryHubProtocol` (pooled) or directly from `byte[]` (server send).

### Client
- **`AcSignalRClientBase.cs`** — Abstract SignalR client managing `HubConnection`, request/response tracking via pooled `SignalRRequestModel`. Methods: `SendMessageToServerAsync<TResponse>()`, CRUD helpers (Post, Get, GetAll, GetAllInto). Configurable timeouts.
- **`IAcSignalRHubClient.cs`** — Client interface + `SignalResponseDataMessage` (sealed, `ResponseData` is `SignalData?`, supports JSON/Binary with GZip, caching, diagnostics, `Dispose()` returns buffers to ArrayPool).
- **`IAcSignalRHubBase.cs`** — Base hub interface: `OnReceiveMessage(int messageTag, int? requestId, SignalParams signalParams, SignalData data)`.
- **`ISignalParams.cs`** — `ISignalParams` base interface + `SignalParams` (Status, DataSerializerType, Parameters `byte[]?`). Metadata travels as separate hub argument (AcBinary serialized), payload `SignalData` uses protocol fast-path (ArrayPool-backed). Parameters and data are independent — both nullable in any direction.

### Message Tagging
- **`SignalMessageTagAttribute.cs`** — Three attributes: `TagAttribute` (base, int messageTag), `SignalRAttribute` (server method routing + client notification), `SignalRSendToClientAttribute` (client-side receive).
- **`AcSignalRTags.cs`** — Static constants: `None`, `PingTag`, `EchoTag`.
- **`SignalRCrudTags.cs`** — Sealed class bundling 5 independent CRUD tag integers. `GetMessageTagByTrackingState()` maps `TrackingState` -> tag. See `AyCode.Services.Server/docs/SIGNALR_DATASOURCE.md`.
- **`SendToClientType.cs`** — Enum: None, Others, Caller, All.

### Serialization & Pooling
- **`SignalRSerializationHelper.cs`** — Static helpers: `SerializeToBinary()`, `DeserializeFromBinary()`, compressed JSON variants, `CreateResponseData()`.
- **`SignalRRequestModel.cs`** — Poolable (`IResettable`) request tracking model with `ObjectPool` for reuse.