Semantic conventions

Feature bits

Every record belongs to exactly one feature, and is only collected while that feature is both switched on by configuration (options.Features) and granted by the user. The numbers are the same in C# (BelemetryFeatures) and in the script (Features), and they are what BitBelemetry.setConsent takes.

Browser records

Events are log records with an eventName, the way the OpenTelemetry Events API models them. Spans use the OTLP span kinds (1 internal, 2 server, 3 client) and status codes (0 unset, 1 ok, 2 error), and log severities use the OTLP SeverityNumber. Times are milliseconds since the Unix epoch, from performance.timeOrigin + performance.now().

.NET records

Resource attributes

The resource describes the producer rather than the event, and travels once per batch. The first eight are common to both sides; the rest say which side the record came from.

options.ResourceAttributes adds your own, and outside the browser OTEL_RESOURCE_ATTRIBUTES is merged in first, so explicit options win.

Browser storage keys

Belemetry sets no cookies. These are the only keys it writes, and each one is gated by the feature it serves.

Revoking a feature clears its key: Persistence removes the queue, Sessions the stored session, and UserTracking the pseudo id and the user id.

Browser configuration

<BelemetryScript /> writes this object into <script type="application/json" id="bit-belemetry-config">, built from the server's BelemetryOptions, and the module starts from it on load. <BelemetryInitializer /> passes the same object to start(config), which is idempotent. Without .NET, pass it to BitBelemetry.start yourself - every field is optional.

{
  "service": { "name": "MyApp", "version": "1.0.0", "namespace": null, "instanceId": null, "environment": "Production" },
  "resource": { "any.attribute": "value" },             // extra resource attributes
  "sdkVersion": "10.6.2",
  "transport": "direct",                                 // "direct" (JS exports itself) | "relay" (JS hands records to .NET)
  "exporters": [
    { "type": "otlp", "endpoint": "http://localhost:4318", "tracesEndpoint": null, "logsEndpoint": null,
      "protocol": "http/protobuf", "headers": { "x-api-key": "..." }, "compression": "none", "signals": 3 },   // protocol: http/protobuf | http/json ; compression: none | gzip
    { "type": "azureMonitor", "connectionString": "InstrumentationKey=...;IngestionEndpoint=https://...", "maskIp": true,
      "compression": "none", "signals": 3 },
    { "type": "console" }
  ],
  "features": 4095,                                      // instrumentations switched on by configuration
  "consent": { "default": 0, "persist": true, "honorGlobalPrivacyControl": true, "pendingLimit": 500 },
  "pageViews": { "trackHashChanges": false },
  "interactions": { "events": ["click"], "captureText": false, "maxTextLength": 64 },
  "performance": { "webVitals": true, "documentLoad": true, "resources": false, "longTasks": false },
  "dependencies": { "fetch": true, "xhr": true, "propagateTraceContextTo": ["same-origin"], "ignoreUrls": ["/_framework/", "/_blazor", "/_content/"] },
  "errors": { "ignoreMessages": ["ResizeObserver loop"] },
  "logs": { "captureConsole": false, "consoleLevels": ["error", "warn"] },
  "privacy": { "redactQueryParameters": ["token","code","password","pwd","secret","key","apikey","api_key","auth","authorization","session","sid","sig","signature","email","access_token","id_token","refresh_token"],
               "stripQueryString": false, "stripFragment": true, "scrubPatterns": true, "collectUserAgent": true, "blockedAttributes": [] },
  "session": { "inactivityTimeoutMinutes": 30, "maxDurationMinutes": 1440 },
  "sampling": { "sessionRatio": 1.0 },
  "batch": { "maxQueueSize": 1024, "maxBatchSize": 100, "flushIntervalMs": 5000 },
  "persistence": { "enabled": true, "maxBytes": 1048576, "maxAgeHours": 48, "retryIntervalMs": 60000 },
  "debug": false
}

• propagateTraceContextTo entries are "same-origin", "*", or a regex source matched against the absolute URL.
• ignoreUrls and ignoreMessages are regex sources.

The constants

BelemetrySemanticConventions holds every attribute and event name above as a const string, for processors and custom exporters that read or write them - so a typo is a compile error rather than an attribute nobody queries.