19c7e6880f
Add connection lifecycle (fixed-interval auto-reconnect, immediate bad quality on disconnect, transparent re-subscribe), synchronous write failure errors to scripts, periodic tag path resolution retry, and enhanced health reporting with tag resolution counts. Update cross-references in Health Monitoring and Site Runtime.
63 lines
2.9 KiB
Markdown
63 lines
2.9 KiB
Markdown
# Component: Health Monitoring
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## Purpose
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The Health Monitoring component collects and reports operational health metrics from site clusters to the central cluster, providing engineers with visibility into the status of the distributed system.
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## Location
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Site clusters (metric collection and reporting). Central cluster (aggregation and display).
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## Responsibilities
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### Site Side
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- Collect health metrics from local subsystems.
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- Periodically report metrics to the central cluster via the Communication Layer.
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### Central Side
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- Receive and store health metrics from all sites.
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- Detect site connectivity status (online/offline) based on heartbeat presence.
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- Present health data in the Central UI dashboard.
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## Monitored Metrics
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| Metric | Source | Description |
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|--------|--------|-------------|
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| Site online/offline | Communication Layer | Whether the site is reachable (based on heartbeat) |
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| Active/standby node status | Cluster Infrastructure | Which node is active, which is standby |
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| Data connection health | Data Connection Layer | Connected/disconnected/reconnecting per data connection |
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| Tag resolution counts | Data Connection Layer | Per connection: total subscribed tags vs. successfully resolved tags |
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| Script error rates | Site Runtime (Script Actors) | Frequency of script failures |
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| Alarm evaluation error rates | Site Runtime (Alarm Actors) | Frequency of alarm evaluation failures |
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| Store-and-forward buffer depth | Store-and-Forward Engine | Pending messages by category (external, notification, DB write) |
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## Reporting Protocol
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- Sites send a **health report message** to central at a configurable interval (e.g., every 30 seconds).
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- Each report contains the current values of all monitored metrics.
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- If central does not receive a report within a timeout window, the site is marked as **offline**.
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## Central Storage
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- Health metrics are held **in memory** at the central cluster for display in the UI.
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- No historical health data is persisted — the dashboard shows current/latest status only.
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- Site connectivity history (online/offline transitions) may optionally be logged via the Audit Log or a separate mechanism if needed in the future.
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## No Alerting
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- Health monitoring is **display-only** for now — no automated notifications or alerts are triggered by health status changes.
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- This can be extended in the future.
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## Dependencies
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- **Communication Layer**: Transports health reports from sites to central.
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- **Data Connection Layer (site)**: Provides connection health metrics.
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- **Site Runtime (site)**: Provides script error rate and alarm evaluation error rate metrics.
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- **Store-and-Forward Engine (site)**: Provides buffer depth metrics.
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- **Cluster Infrastructure (site)**: Provides node role status.
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## Interactions
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- **Central UI**: Health Monitoring Dashboard displays aggregated metrics.
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- **Communication Layer**: Health reports flow as periodic messages.
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