367 lines
8.4 KiB
HTML
367 lines
8.4 KiB
HTML
<!doctype html>
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<html lang="en">
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<head>
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<meta charset="utf-8"/>
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<title>Databuffer API 4 Documentation</title>
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<meta name="keywords" content="PSI, DAQ, Databuffer">
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<meta name="author" content="Dominik Werder">
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<link rel="shortcut icon" href="about:blank"/>
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<link rel="stylesheet" href="style.css"/>
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</head>
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<body>
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<h1>Databuffer API 4 Documentation</h1>
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<p>Documented here are the endpoints for databuffer API 4. The endpoints of the "original" unversioned API is documented at
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<a href="https://git.psi.ch/sf_daq/ch.psi.daq.databuffer/blob/master/ch.psi.daq.queryrest/Readme.md">this location</a>.</p>
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<h2>Available backends</h2>
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Currently available:
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<ul>
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<li>sf-databuffer</li>
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</ul>
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<h2>Timestamp format</h2>
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<p>The result encodes timestamps in the form:</p>
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<pre>{
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"tsAnchor": 1623909860, // Time-anchor of this result in UNIX epoch seconds.
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"tsOffMs": [573, 15671, 37932, ...], // Millisecond-offset to tsAnchor for each event/bin-edge.
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"tsOffNs": [422901, 422902, 422903, ...], // Nanosecond-offset to tsAnchor in addition to tsOffMs for each event/bin-edge.
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}</pre>
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<p>which results in these nanosecond-timestamps:</p>
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<pre>1623909860573422901
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1623909875671422902
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1623909897932422903</pre>
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<p>Formally: tsAbsolute = tsAnchor * 10<sup>9</sup> + tsOffMs * 10<sup>6</sup> + tsOffNs</p>
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<p>Two reasons lead to this choice of timestamp format:</p>
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<ul>
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<li>Javascript can not represent the full nanosecond-resolution timestamps in a single numeric variable.</li>
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<li>The lowest 6 digits of the nanosecond timestamp are anyway abused by the timing system to emit a pulse-id.</li>
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</ul>
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<h2>API functions</h2>
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<p>Currently available functionality:</p>
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<ul>
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<li><a href="#search-channel">Search channel</a></li>
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<li><a href="#query-binned">Query binned data</a></li>
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<li><a href="#query-events">Query unbinned event data</a></li>
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</ul>
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<a id="search-channel"></a>
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<h2>Search channel</h2>
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<p><strong>Method:</strong> GET</p>
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<p><strong>URL:</strong> https://data-api.psi.ch/api/4/search/channel</p>
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<p><strong>Query parameters:</strong></p>
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<ul>
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<li>nameRegex (e.g. "LSCP.*6")</li>
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<li>sourceRegex (e.g. "178:9999")</li>
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<li>descriptionRegex (e.g. "celsius")</li>
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</ul>
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<p><strong>Request header:</strong> "Accept" must be "application/json"</p>
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<h4>CURL example:</h4>
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<pre>
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curl -H 'Accept: application/json' 'https://data-api.psi.ch/api/4/search/channel?sourceRegex=CV.E.+37&nameRegex=120.+y2$'
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</pre>
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<h4>Example response:</h4>
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<pre>
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{
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"channels": [
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{
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"name": "S10MA01-DBPM120:Y2",
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"backend": "sf-databuffer",
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"source": "tcp://S20-CVME-DBPM2371:9000",
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"type": "Float32",
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"shape": [],
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"unit": "",
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"description": ""
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},
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{
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"name": "S20SY02-DBPM120:Y2",
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"backend": "sf-databuffer",
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"source": "tcp://S20-CVME-DBPM2371:9000",
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"type": "Float32",
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"shape": [],
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"unit": "",
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"description": ""
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}
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]
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}
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</pre>
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<p>The search constraints are AND'd.</p>
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<a id="query-events"></a>
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<h2>Query event data</h2>
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<p>Returns the full event values in a given time range.</p>
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<p><strong>Method:</strong> GET</p>
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<p><strong>URL:</strong> https://data-api.psi.ch/api/4/events</p>
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<p><strong>Query parameters:</strong></p>
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<ul>
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<li>channelBackend (e.g. "sf-databuffer")</li>
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<li>channelName (e.g. "S10CB02-RBOC-DCP10:FOR-AMPLT-AVG")</li>
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<li>begDate (e.g. "2021-05-26T07:10:00.000Z")</li>
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<li>endDate (e.g. "2021-05-26T07:16:00.000Z")</li>
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</ul>
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<p><strong>Request header:</strong> "Accept" must be "application/json"</p>
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<h4>Timeout</h4>
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<p>If the requested range takes too long to retrieve, then the flags <strong>timedOut: true</strong> will be set.</p>
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<h4>CURL example:</h4>
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<pre>
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curl -H 'Accept: application/json' 'https://data-api.psi.ch/api/4/events?channelBackend=sf-databuffer
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&channelName=S10CB02-RBOC-DCP10:FOR-AMPLT-AVG&begDate=2021-05-26T07:10:00.000Z&endDate=2021-05-26T07:16:00.000Z'
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</pre>
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<p>Example response:</p>
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<pre>
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{
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"finalisedRange": true,
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"tsAnchor": 1623763172,
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"tsMs": [
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5,
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15,
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25,
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35
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],
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"tsNs": [
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299319,
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299320,
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299321,
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299322
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],
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"values": [
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0.6080216765403748,
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0.6080366969108582,
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0.6080275177955627,
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0.6080636382102966
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]
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}
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</pre>
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<h4>Finalised range</h4>
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<p>If the server can determine that no more data will be added to the requested time range
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then it will add the flag <strong>finalisedRange: true</strong> to the response.</p>
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<a id="query-binned"></a>
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<h2>Query binned data</h2>
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<p><strong>Method:</strong> GET</p>
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<p><strong>URL:</strong> https://data-api.psi.ch/api/4/binned</p>
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<p><strong>Query parameters:</strong></p>
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<ul>
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<li>channelBackend (e.g. "sf-databuffer")</li>
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<li>channelName (e.g. "SLAAR-LSCP4-LAS6891:CH7:1")</li>
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<li>begDate (e.g. "2021-05-26T07:10:00.000Z")</li>
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<li>endDate (e.g. "2021-05-26T07:16:00.000Z")</li>
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<li>binCount (number of requested bins in time-dimension, e.g. "6")</li>
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<li>binningScheme (optional)</li>
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<ul>
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<li>if not specified: waveform gets first binned to a scalar.</li>
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<li>"binningScheme=binnedX&binnedXcount=13": waveform gets first binned to 13 bins in X-dimension (waveform-dimension).</li>
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<li>"binningScheme=binnedX&binnedXcount=0": waveform is not binned in X-dimension but kept at full length.</li>
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</ul>
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</ul>
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<p><strong>Request header:</strong> "Accept" must be "application/json"</p>
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<h4>CURL example:</h4>
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<pre>
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curl -H 'Accept: application/json' 'https://data-api.psi.ch/api/4/binned?channelBackend=sf-databuffer
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&channelName=SLAAR-LSCP4-LAS6891:CH7:1&begDate=2021-05-25T00:00:00.000Z&endDate=2021-05-26T00:00:00.000Z&binCount=3'
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</pre>
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<h4>Partial result</h4>
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<p>If the requested range takes longer time to retrieve, then a partial result with at least one bin is returned.
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The partial result will contain the necessary information to send another request with a range that
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starts with the first not-yet-retrieved bin.
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This information is provided by the <strong>continueAt</strong> and <strong>missingBins</strong> fields.
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This enables the user agent to start the presentation to the user while updating the user interface
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as new bins are received.</p>
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<h4>Example response (without usage of binningScheme):</h4>
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<pre>{
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"avgs": [
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16204.087890625,
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16204.3798828125,
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16203.9296875,
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16204.232421875,
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16202.974609375,
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16203.208984375,
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16203.4345703125
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],
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"counts": [
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1000,
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999,
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1000,
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999,
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1000,
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999,
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1000
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],
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"finalisedRange": true,
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"maxs": [
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48096,
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48100,
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48094,
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48096,
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48096,
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48095,
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48096
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],
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"mins": [
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0,
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0,
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0,
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0,
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0,
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0,
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0
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],
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"tsAnchor": 1623769850,
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"tsMs": [
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0,
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10000,
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20000,
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30000,
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40000,
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50000,
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60000,
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70000
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],
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"tsNs": [
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0,
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0,
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0,
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0,
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0,
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0,
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0,
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0
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]
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}
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</pre>
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<h4>Example response (waveform channel and usage of binningScheme):</h4>
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<pre>{
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"tsAnchor": 1623769950,
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"tsMs": [
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0,
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10000,
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20000,
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30000,
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40000,
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50000,
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60000,
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70000
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],
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"tsNs": [
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0,
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0,
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0,
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0,
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0,
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0,
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0,
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0
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],
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"finalisedRange": true,
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"counts": [
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1000,
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1000,
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...
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],
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"avgs": [
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[
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0.013631398789584637,
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34936.76953125,
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45045.5078125,
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31676.30859375,
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880.7999877929688,
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576.4010620117188,
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295.1236877441406
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],
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[
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0.01851877197623253,
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34935.734375,
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45044.2734375,
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31675.359375,
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880.7310791015625,
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576.3038330078125,
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295.06134033203125
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],
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...
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],
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"maxs": [
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[
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111,
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48093,
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45804,
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47122,
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1446,
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783,
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431
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],
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[
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120,
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48092,
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45803,
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47124,
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1452,
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782,
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431
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],
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...
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],
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"mins": [
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[
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0,
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0,
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44329,
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267,
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519,
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394,
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0
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],
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[
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0,
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0,
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44327,
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265,
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514,
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395,
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0
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],
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...
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]
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}
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</pre>
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<h4>Complete result</h4>
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<p>If the result does not contain a <strong>continueAt</strong> key then the result is complete.</p>
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<h4>Finalised range</h4>
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<p>If the server can determine that no more data will be added to the requested time range
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then it will add the flag <strong>finalisedRange: true</strong> to the response.</p>
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<h2>Feedback and comments very much appreciated!</h2>
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<p>dominik.werder@psi.ch</p>
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<p>or please assign me a JIRA ticket.</p>
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<div id="footer"></div>
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</body>
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</html>
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