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Crate subscriber

Crate subscriber 

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Diagnostic subscriber that writes live NATS LabJack samples to CSV files.

The streamer publishes each channel’s scans as FlatBuffer sampler::Scan messages on NATS, and the archiver normally turns them into Parquet. This binary is for inspecting that live stream without running the archiver. It makes a plain (non-JetStream) core NATS subscription to the live subject wildcard from subjects::live_labjack_stream_subject, decodes each scan, and appends one CSV file per asset and channel. It only sees messages published while it is running.

Each CSV file is named labjack_<asset>_<channel>.csv (for example labjack_001_ch03.csv) and has the header sequence,timestamp,raw_value. The asset is taken from the subject for legacy subjects and from ASSET_NUMBER otherwise. Every sample becomes one row: the scan’s sequence number, the sample time as RFC 3339 UTC, and the value as published.

§Configuration

  • NATS_SUBJECT - Subject root. Default: avenabox.
  • ASSET_NUMBER - Asset number used in CSV file names for structured subjects, and as the source when neither SOURCE_ID nor LABJACK_NAME is set. Unparseable values fall back to the default. Default: 1.
  • SITE_ID - Site ID for the structured subject layout.
  • BOX_ID - Box ID for the structured subject layout.
  • LABJACK_NAME - LabJack name, used as the source when SOURCE_ID is unset.
  • SOURCE_TYPE - Read and passed on, but does not affect the subject.
  • SOURCE_ID - Source ID for the structured subject layout.
  • OUTPUT_DIR - Directory for the CSV files, created if missing. Default: outputs.
  • NATS_SERVERS - Comma-separated NATS server URLs. Default: nats://127.0.0.1:4222.
  • NATS_CREDS_FILE - NATS credentials file. Default: apt.creds.

With the defaults the subscription is the legacy wildcard avenabox.*.data.*, which matches every asset; each file is named after the asset in its subject. Setting any of SITE_ID, BOX_ID or SOURCE_ID, or NATS_SUBJECT=avenars, switches to <root>.<site>.<box>.<source>.live.*.

Modules§

nats_config 🔒
Shared NATS server-list and JetStream context helpers.
sample_data_generated 🔒
subjects 🔒
NATS subject builders for LabJack live data and archive exports.

Functions§

asset_for_subject 🔒
Finds the asset number a message belongs to.
csv_file_name 🔒
Builds the CSV file name for one asset and channel.
extract_channel_token 🔒
Extracts the final subject token, which is expected to be the channel name.
main 🔒
Starts the live NATS subscriber and appends decoded samples to CSV.
open_csv_for_channel 🔒
Opens or creates the per-channel CSV file and writes its header if needed.
timestamp_unix_ns_to_rfc3339 🔒
Converts a Unix nanosecond timestamp into RFC 3339 text in UTC.