965e430f48
Provides technical documentation covering OPC UA server, address space, Galaxy repository, MXAccess bridge, data types, read/write, subscriptions, alarms, historian, incremental sync, configuration, dashboard, service hosting, and CLI tool. Updates README with component documentation table. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
91 lines
4.7 KiB
Markdown
91 lines
4.7 KiB
Markdown
# OPC UA Server
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The OPC UA server component hosts the Galaxy-backed namespace on a configurable TCP endpoint and exposes deployed System Platform objects and attributes to OPC UA clients.
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## Configuration
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`OpcUaConfiguration` defines the server endpoint and session settings. All properties have sensible defaults:
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| Property | Default | Description |
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|----------|---------|-------------|
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| `Port` | `4840` | TCP port the server listens on |
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| `EndpointPath` | `/LmxOpcUa` | URI path appended to the base address |
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| `ServerName` | `LmxOpcUa` | Application name presented to clients |
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| `GalaxyName` | `ZB` | Galaxy name used in the namespace URI |
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| `MaxSessions` | `100` | Maximum concurrent client sessions |
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| `SessionTimeoutMinutes` | `30` | Idle session timeout |
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| `AlarmTrackingEnabled` | `false` | Enables `AlarmConditionState` nodes for alarm attributes |
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The resulting endpoint URL is `opc.tcp://0.0.0.0:{Port}{EndpointPath}`, e.g., `opc.tcp://0.0.0.0:4840/LmxOpcUa`.
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The namespace URI follows the pattern `urn:{GalaxyName}:LmxOpcUa` and serves as both the `ApplicationUri` and `ProductUri`.
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## Programmatic ApplicationConfiguration
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`OpcUaServerHost` builds the entire `ApplicationConfiguration` in code. There are no XML configuration files. This keeps deployment simple on factory floor machines where editing XML is error-prone.
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The configuration covers:
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- **ServerConfiguration** -- base address, session limits, security policies, and user token policies
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- **SecurityConfiguration** -- certificate store paths under `%LOCALAPPDATA%\OPC Foundation\pki\`, auto-accept enabled
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- **TransportQuotas** -- 4 MB max message/string/byte-string size, 120-second operation timeout, 1-hour security token lifetime
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- **TraceConfiguration** -- OPC Foundation SDK tracing is disabled (output path `null`, trace masks `0`); all logging goes through Serilog instead
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## Security Policy
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The server runs with `MessageSecurityMode.None` and `SecurityPolicies.None`. Only anonymous user tokens are accepted:
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```csharp
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SecurityPolicies = { new ServerSecurityPolicy
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{
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SecurityMode = MessageSecurityMode.None,
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SecurityPolicyUri = SecurityPolicies.None
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} },
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UserTokenPolicies = { new UserTokenPolicy(UserTokenType.Anonymous) }
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```
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This is intentional for plant-floor deployments where the server sits on an isolated OT network. Galaxy-level security classification controls write access per attribute rather than at the transport layer.
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## Certificate handling
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On startup, `OpcUaServerHost.StartAsync` calls `CheckApplicationInstanceCertificate(false, 2048)` to locate or create a 2048-bit self-signed certificate. The certificate subject follows the format `CN={ServerName}, O=ZB MOM, DC=localhost`. Certificate stores use the directory-based store type under `%LOCALAPPDATA%\OPC Foundation\pki\`:
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| Store | Path suffix |
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|-------|-------------|
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| Own | `pki/own` |
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| Trusted issuers | `pki/issuer` |
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| Trusted peers | `pki/trusted` |
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| Rejected | `pki/rejected` |
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`AutoAcceptUntrustedCertificates` is set to `true` so the server does not reject client certificates.
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## Server class hierarchy
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### LmxOpcUaServer extends StandardServer
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`LmxOpcUaServer` inherits from the OPC Foundation `StandardServer` base class and overrides two methods:
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- **`CreateMasterNodeManager`** -- Instantiates `LmxNodeManager` with the Galaxy namespace URI, the `IMxAccessClient` for runtime I/O, performance metrics, and an optional `HistorianDataSource`. The node manager is wrapped in a `MasterNodeManager` with no additional core node managers.
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- **`LoadServerProperties`** -- Returns server metadata: manufacturer `ZB MOM`, product `LmxOpcUa Server`, and the assembly version as the software version.
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### Session tracking
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`LmxOpcUaServer` exposes `ActiveSessionCount` by querying `ServerInternal.SessionManager.GetSessions().Count`. `OpcUaServerHost` surfaces this for status reporting.
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## Startup and Shutdown
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`OpcUaServerHost.StartAsync` performs the following sequence:
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1. Build `ApplicationConfiguration` programmatically
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2. Validate the configuration via `appConfig.Validate(ApplicationType.Server)`
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3. Create `ApplicationInstance` and check/create the application certificate
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4. Instantiate `LmxOpcUaServer` and start it via `ApplicationInstance.Start`
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`OpcUaServerHost.Stop` calls `_server.Stop()` and nulls both the server and application instance references. The class implements `IDisposable`, delegating to `Stop`.
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## Key source files
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- `src/ZB.MOM.WW.LmxOpcUa.Host/OpcUa/OpcUaServerHost.cs` -- Application lifecycle and programmatic configuration
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- `src/ZB.MOM.WW.LmxOpcUa.Host/OpcUa/LmxOpcUaServer.cs` -- StandardServer subclass and node manager creation
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- `src/ZB.MOM.WW.LmxOpcUa.Host/Configuration/OpcUaConfiguration.cs` -- Configuration POCO
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