Limits should be fetched from the mdb and not the parameter archive

[akhenry]

Is your feature request related to a problem? Please describe. The Open MCT-Yamcs limit provider currently fetches limit definitions from the parameter archive. This has a couple of downsides:

1. We will not be able to render limit lines for parameters with no values yet. This would require the user to reload a plot once values have been received
2. Requests to the parameter archive are expensive

Additionally, limit information should be cached to avoid having to make an extra request to the server for limit information every time we want to render limits in a plot.

Describe the solution you'd like Static limit information is provided by the MDB API which is already used for fetching the dictionary. So, it could be fetched once when the dictionary is loaded and cached in memory with other telemetry metadata.

[scottbell]

One issue with this is that alarms come from the parameter archive like so:

"alarmRange": [
    {
        "level": "WARNING",
        "minExclusive": -5,
        "maxExclusive": 10
    },
    {
        "level": "CRITICAL",
        "minExclusive": -20,
        "maxExclusive": 15
    }
]

From MDB, they're closer to how they're represented in XTCE, e.g.:

"defaultAlarm": {
    "minViolations": 1,
    "staticAlarmRange": [
        {
            "level": "WARNING",
            "minExclusive": -5,
            "maxExclusive": 10
        },
        {
            "level": "CRITICAL",
            "minExclusive": -20,
            "maxExclusive": 15
        }
    ]
}

I'll see if there's a way to ask the MDB to give us alarms closer to how the parameter archive does.

[scottbell]

@akhenry Though I suppose if we really only support staticAlarmRange, I could just look for this explicitly.

[scottbell]

@akhenry to ask Mark Rose for how XTCE alarms will be defined for 👆

[scottbell]

After discussion, we decided to go with the assumption we'll have a defaultAlarm with a staticAlarmRange.

[scottbell]

To test:

• Replace XTCE in yamcs-quickstart/src/main/yamcs/mdb/xtce.xml with the attached XTCE that contains some alarms (unzip it first): xtce.xml.zip
• Start YAMCS up, along with its python simulator
• Make a new "Overlay Plot" with the "Latitude" object
• Turn on "Alarm Markers"
• Ensure you can see the Alarms/Limits in the Plot (the red & yellow lines):

[shefalijoshi]

Verified - I do see limits for the navcamPanAngle endpoint: