Martino Ferrari
232 lines
6.4 KiB
Markdown
232 lines
6.4 KiB
Markdown
# StreamHub WebSocket API
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StreamHub exposes a single WebSocket server (default port **8090**, any URL path).
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Text frames carry JSON commands/events; binary frames carry data pushes and
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trigger captures. The Go reference hub (`Client/udpstreamer`) implements the
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identical protocol; both the browser SPA and the ImGui client work against either.
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For the upstream UDPS wire format (source → hub) see [Protocol.md](Protocol.md).
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All numbers in binary frames are **little-endian**. All timestamps are
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**Unix wall-clock seconds** (float64) — see *Time base* in
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[StreamHub-Developer.md](StreamHub-Developer.md).
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---
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## 1. Commands (client → hub, JSON text frames)
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Every command is a JSON object with a `type` field.
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### `ping`
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```json
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{"type":"ping"}
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```
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Reply (unicast): `{"type":"pong"}`.
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### `addSource`
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```json
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{"type":"addSource","label":"PSU","addr":"192.168.0.10:44500",
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"multicastGroup":"239.0.0.1","dataPort":44503}
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```
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- `addr` — `host:port` of the UDPStreamer control port.
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- `multicastGroup` / `dataPort` — optional; if present the hub joins the
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multicast group for DATA and keeps a TCP control connection for CONNECT/CONFIG.
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- The hub assigns ids `s1`, `s2`, … and broadcasts an updated `sources` event.
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### `removeSource`
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```json
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{"type":"removeSource","id":"s1"}
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```
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### `saveSources`
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```json
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{"type":"saveSources"}
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```
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Persists the current dynamically-added source list to the hub's `SourcesFile`
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(JSON array of `{label,addr,multicastGroup,dataPort}`); it is reloaded at startup.
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### `getSources` / `getConfig` / `getStats`
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```json
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{"type":"getSources"}
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{"type":"getConfig","sourceId":"s1"}
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{"type":"getStats"}
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```
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Force a broadcast of the corresponding event.
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### `setTrigger`
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```json
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{"type":"setTrigger","signal":"s1:Sine","edge":"rising","threshold":0.0,
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"windowSec":0.1,"prePercent":20,"mode":"normal"}
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```
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- `signal` — full key `src:sig`, or `src:sig[i]` to trigger on element *i* of a
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multi-element PACKET signal.
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- `edge` — `"rising"`, `"falling"` or `"both"`.
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- `windowSec` — total capture window (clamped to 1e-4 … 10 s).
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`preSec = windowSec * prePercent / 100`, `postSec = windowSec − preSec`.
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- `mode` — `"normal"` (auto-rearm ~200 ms after capture) or `"single"`
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(stays TRIGGERED until `rearm`).
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### `arm` / `disarm` / `rearm` / `trigStop`
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```json
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{"type":"arm"}
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{"type":"disarm"}
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{"type":"rearm"}
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{"type":"trigStop","stopped":true}
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```
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- `arm` — IDLE → ARMED.
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- `disarm` — any state → IDLE.
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- `rearm` — TRIGGERED → ARMED (single mode).
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- `trigStop` — sets the *stopped* flag suppressing auto-rearm in normal mode;
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omit `stopped` to toggle.
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Every transition is broadcast as a `triggerState` event.
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### `zoom`
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```json
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{"type":"zoom","reqId":17,"t0":1765370000.123,"t1":1765370000.223,
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"n":2400,"signals":"s1:Sine,s2:Wave[0]"}
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```
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- `reqId` — echoed in the reply; lets the client match request/response.
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- `t0`/`t1` — Unix seconds window.
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- `n` — target points per signal. Absent or `<10` → 2400; `n ≤ 0` → **no
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decimation** (raw ring contents).
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- `signals` — comma-separated full keys; absent → all signals of all sources.
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- The reply is **unicast** to the requesting client only.
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### `setMaxPoints`
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```json
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{"type":"setMaxPoints","maxPoints":50000}
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```
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Resizes all ring buffers (applied safely inside the push loop; push cursors are
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reset). Broadcasts `maxPointsUpdated`.
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---
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## 2. Events (hub → client, JSON text frames)
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### `sources`
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```json
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{"type":"sources","sources":[
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{"id":"s1","label":"PSU","addr":"192.168.0.10:44500","state":"streaming"}]}
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```
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Sent on client connect, after add/remove/getSources, and when a source first
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delivers its CONFIG.
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### `config`
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```json
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{"type":"config","sourceId":"s1","publishMode":0,"signals":[
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{"name":"Sine","typeCode":10,"quantType":0,"numDimensions":0,
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"numRows":1,"numCols":1,"rangeMin":-1.0,"rangeMax":1.0,
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"timeMode":0,"samplingRate":5000000.0,"timeSignalIdx":-1,"unit":"V"}]}
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```
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Field semantics follow the UDPS signal descriptor ([Protocol.md](Protocol.md)).
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`numElements = numRows × numCols`.
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### `stats`
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Sent at `StatsRate` Hz (default 1 Hz):
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```json
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{"type":"stats","sources":{"s1":{
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"state":"streaming","totalReceived":1234,"totalLost":0,
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"rateHz":100.1,"rateStdHz":0.3,
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"fragsPerCycle":3.0,"bytesPerCycle":4200.0,
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"cycleAvgMs":10.0,"cycleStdMs":0.1,"cycleMinMs":9.8,"cycleMaxMs":10.4,
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"cycleHistMin":9.8,"cycleHistMax":10.4,"cycleHist":[0,1,5,"…(20 bins)"]}}}
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```
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### `triggerState`
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```json
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{"type":"triggerState","state":"triggered","mode":"normal",
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"stopped":false,"trigTime":1765370000.1234567}
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```
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`state` ∈ `idle | armed | collecting | triggered`; `trigTime` present once a
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trigger has fired.
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### `zoom` (reply)
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```json
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{"type":"zoom","reqId":17,"signals":{
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"s1:Sine":{"t":[1765370000.1230000,"…"],"v":[0.123456789,"…"]}}}
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```
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`t` is serialised with `%.17g` (full float64 precision — required for
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µs windows at Unix-epoch magnitudes), `v` with `%.9g`.
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### `maxPointsUpdated`
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```json
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{"type":"maxPointsUpdated","maxPoints":50000}
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```
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---
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## 3. Binary frames (hub → client)
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The first byte of every binary WS frame is a **version** discriminator.
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### Version 1 — data push
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Sent at `PushRate` Hz per source. Contains **only the samples that are new
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since the previous push** (per-signal cursors hub-side), LTTB-decimated to at
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most `MaxPushPoints` (default 50) per signal.
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```
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[1] version = 1
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[1] sourceIdLen (L)
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[L] sourceId (UTF-8, no NUL)
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[4] numSignals (uint32)
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per signal:
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[2] keyLen (uint16) (K)
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[K] key = signal name; "name[i]" per element for multi-element PACKET signals
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[4] pairCount (uint32) (N)
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[N×8] t (float64, Unix seconds)
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[N×8] v (float64, physical units)
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```
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Clients must append samples verbatim — there is no overlap between pushes.
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### Version 2 — trigger capture
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Broadcast once per capture (FSM COLLECTING → TRIGGERED). Contains *all*
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signals over `[trigTime − preSec, trigTime + postSec]`, each LTTB-decimated
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to ≤ 20 000 points.
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```
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[1] version = 2
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[8] trigTime (float64, Unix seconds)
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[8] preSec (float64)
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[8] postSec (float64)
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[4] numSignals (uint32)
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per signal:
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[2] keyLen (uint16) (K)
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[K] fullKey = "src:sig" (UTF-8)
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[4] pairCount (uint32) (N)
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[N×8] t (float64, Unix seconds)
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[N×8] v (float64)
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```
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---
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## 4. Limits
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| Limit | Value |
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|-------|-------|
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| Concurrent WS clients | 16 |
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| UDPS source sessions | 32 |
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| Max received WS payload | 64 KiB |
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| Max sent WS payload | 4 MiB |
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