Java-side HL7 telemetry (waveform-reader) #176

Definition of Done / Acceptance Criteria

• For the HL7 feed, we can see what variables are coming into which beds, in real time
• Do not do this by scanning the disk for hl7 bz2 files as was suggested in Monitoring for errors waveform-controller#49. This will hit the disk and CPU too hard, and is completely unnecessary when we have this data in memory when it comes in as HL7.
• Add a "time since last incoming TCP connection" gauge, to distinguish between the upstream feed having gone dead, vs simply having no data in it (which the "time since most recent hl7 file" gauge already catches)

Testing

No response

Documentation

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Dependencies

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Details and Comments

Although you can currently see this in streamlit, it's kind of clunky for this use case. And it relies on the waveform data coming into Emap-Star itself, which I think is not a dependency we would wish to maintain.

Implementation requires telemetry to be added to the waveform-reader. Ie. using Otel in Java/Spring. We haven't done that before so it would be an extra step to work out how.

Suggest using an Otel counter, increase it by the number of data points, with attrs of the source bed ID and the variable ID. Similar to what we do in the waveform-controller, but further up in the pipeline.