# Test Infrastructure: LmxFakeProxy

## Overview

LmxFakeProxy is a .NET gRPC server that implements the `scada.ScadaService` proto (full parity with the real LmxProxy server) but bridges to the OPC UA test server instead of System Platform MXAccess. This enables end-to-end testing of `RealLmxProxyClient` and the LmxProxy DCL adapter.

## Image & Ports

- **Image**: Custom build (`infra/lmxfakeproxy/Dockerfile`)
- **gRPC endpoint**: `localhost:50051`

## Configuration

| Environment Variable | Default | Description |
|---------------------|---------|-------------|
| `PORT` | `50051` | gRPC listen port |
| `OPC_ENDPOINT` | `opc.tcp://localhost:50000` | Backend OPC UA server |
| `OPC_PREFIX` | `ns=3;s=` | Prefix prepended to LMX tags to form OPC UA NodeIds |
| `API_KEY` | *(none)* | If set, enforces API key on all gRPC calls |

## Tag Address Mapping

LMX-style flat addresses are mapped to OPC UA NodeIds by prepending the configured prefix:

| LMX Tag | OPC UA NodeId |
|---------|--------------|
| `Motor.Speed` | `ns=3;s=Motor.Speed` |
| `Pump.FlowRate` | `ns=3;s=Pump.FlowRate` |
| `Tank.Level` | `ns=3;s=Tank.Level` |

## Supported RPCs

Full parity with the `scada.ScadaService` proto:

- **Connect / Disconnect / GetConnectionState** — Session management
- **Read / ReadBatch** — Read tag values via OPC UA
- **Write / WriteBatch / WriteBatchAndWait** — Write values via OPC UA
- **Subscribe** — Server-streaming subscriptions via OPC UA MonitoredItems
- **CheckApiKey** — API key validation

## Verification

1. Ensure the OPC UA test server is running:
```bash
docker ps --filter name=scadalink-opcua
```

2. Start the fake proxy:
```bash
docker compose up -d lmxfakeproxy
```

3. Check logs:
```bash
docker logs scadalink-lmxfakeproxy
```

4. Test with the ScadaLink CLI or a gRPC client.

## Running Standalone (without Docker)

```bash
cd infra/lmxfakeproxy
dotnet run -- --opc-endpoint opc.tcp://localhost:50000 --opc-prefix "ns=3;s="
```

With API key enforcement:
```bash
dotnet run -- --api-key my-secret-key
```

## Relevance to ScadaLink Components

- **Data Connection Layer** — Test `RealLmxProxyClient` and `LmxProxyDataConnection` against real OPC UA data
- **Site Runtime** — Deploy instances with LmxProxy data connections pointing at this server
- **Integration Tests** — End-to-end tests of the LmxProxy protocol path