What is mctLimitState?

[marcelo-earth]

Hi OpenMCT community!

I can't find the definition of mctLimitState in the documentation, and I see that it is used in the code. I ask this because opening the object that brings back historical telemetry data, I see that there is a new property called mctLimitState.

What is it about? Is it okay for it to be undefined?

From openmct-tutorial:

function HistoricalTelemetryPlugin() {
    return function install (openmct) {
        var provider = {
            supportsRequest: function (domainObject) {
                return domainObject.type === 'example.telemetry';
            },
            request: function (domainObject, options) {
                var url = '/history/' +
                    domainObject.identifier.key +
                    '?start=' + options.start +
                    '&end=' + options.end;

                return http.get(url)
                    .then(function (resp) {
                        console.log(resp.data); // 👈
                        return resp.data;
                    });
            }
        };

        openmct.telemetry.addProvider(provider);
    }
}

[jvigliotta]

Hi! What version of Open MCT is the tutorial using when you see this? Also, what branch/step of the tutorial are you on? You can find the Open MCT version by clicking the Open MCT login in the top right. Thanks!

[marcelo-earth]

Hi @jvigliotta ! I'm using Version: 2.0.5, and the branch is completed. I just write a console.log in the HistoricalTelemetryPlugin as I show in the first post. The result is the same:

[jvigliotta]

After further investigation and a little help from @khalidadil (thanks!) I see that this is added here: https://github.com/nasa/openmct/blob/master/src/plugins/plot/configuration/PlotSeries.js#L431 So, it's not coming back from the server, but when viewing the telemetry data in a plot, each datum get's this property. It shouldn't be any issue if it is undefined. It's used by plots to show limit information related to those data.

[marcelo-earth]

Thanks @jvigliotta and @khalidadil!
I understand. Yes, it works well even if it's undefined.

when viewing the telemetry data in a plot, each datum get's this property.
It's used by plots to show limit information related to those data.

I have a doubt. What does mctLimitState indicate about each datum? What does mctLimitState contains when it's not undefined.

Again, so much thanks 🙏 .

[jvigliotta]

@marcelo-earth very sorry for the very long delay, but if you were still wondering and for anyone else interested, if there is a limit provider for the telemetry then a limit state object that contains styling information is returned. From the example in SinewaveLimitProvider.js, we can see the structure:

LIMITS = {
  rh: {
    cssClass: 'is-limit--upr is-limit--red',
    low: RED,
    high: Number.POSITIVE_INFINITY,
    name: 'Red High'
  },
  rl: {
    cssClass: 'is-limit--lwr is-limit--red',
    high: -RED,
    low: Number.NEGATIVE_INFINITY,
    name: 'Red Low'
  },
  yh: {
    cssClass: 'is-limit--upr is-limit--yellow',
    low: YELLOW,
    high: RED,
    name: 'Yellow High'
  },
  yl: {
    cssClass: 'is-limit--lwr is-limit--yellow',
    low: -RED,
    high: -YELLOW,
    name: 'Yellow Low'
  }
};

The limitUtils.js provides a utility to extract the cssClass:

export function getLimitClass(limit, prefix) {
  let cssClass = '';
  //If color exists then use it, fall back to the cssClass
  if (limit.color) {
    cssClass = `${cssClass} ${prefix}${limit.color}`;
  } else if (limit.cssClass) {
    cssClass = `${cssClass}${limit.cssClass}`;
  }

  // If we applied the cssClass then skip these classes
  if (limit.cssClass === undefined) {
    if (limit.isUpper) {
      cssClass = `${cssClass} ${prefix}upr`;
    } else {
      cssClass = `${cssClass} ${prefix}lwr`;
    }

    if (limit.level) {
      cssClass = `${cssClass} ${prefix}${limit.level}`;
    }

    if (limit.needsHorizontalAdjustment) {
      cssClass = `${cssClass} --align-label-right`;
    }

    if (limit.needsVerticalAdjustment) {
      cssClass = `${cssClass} --align-label-below`;
    }
  }

  return cssClass;
}

These classes are defined here: _limits.scss

These styles can then be applied to plot legends, table cells and I believe table rows based on the values of the telemetry.