Create an alarm with Value error handler

🟑 Intermediate

alarm script variable

osp-alarms osp-web osp-scripts osp-variables

In this tutorial, you will learn how to use the Value error handler to automatically create an alarm whenever a value enters an error state.

  • Create a trigger variable that calls a script via a callback.

  • Write a script that throws an exception to publish an error on the target value.

  • Configure the alarm module error handler so that any value error automatically creates an alarm using the value ID as serial and the error message as summary.

  • Display the trigger and the resulting alarm on a dashboard to validate the behavior.

git checkout origin/osp-alarms-configuration .
git checkout origin/osp-web-configuration .
git checkout origin/osp-scripts-configuration .
git checkout origin/osp-variables-configuration .
git checkout origin/example-alarms-created-from-value-error-handler .

Configuration structure

@startuml package "root/trigger" { [value.ospp] as trigger } package "root/error-generator" { [value.ospp] as error } node frontend as "Front-end" node ospalarms as "Alarms" node ospscripts as "Scripts" frontend -[#black]> trigger : <size:11><color:black> **Trigger the script** trigger -[#black]> ospscripts : <size:11><color:black> **Trigger the script** ospscripts -[#black]> error : <size:11><color:firebrick> **Generate an error** error -[#firebrick]r-> ospalarms : <size:11><color:firebrick> **Create alarm** @enduml

Steps

1. Create a variable to trigger the script

root/trigger/value.ospp

{
    "name": "Alarm trigger",
    "description" : "Trigger an alarm",
    "type": "BOOLEAN"
}

root/trigger/owner.variables

{
     "moduleId": "modules.variables.variables-1",
     "default": false,
     "persistent": false
}

root/trigger/callback.ospp

{
    "linkedOutputs": [
        {
            "outputId": "root.error-generator"
        }
    ]
}

2. Configure the alarm value error handler

This will create an alarm when a value is on error using it’s id as the serial and the error message as the summary.

modules/alarms/alarms-1/module.alarms

149    "valueErrorHandler": {
150        "alarmGenerator": {
151            "serial": {
152                "type": "FIELD",
153                "field": "ID"
154            },
155            "severity": 600,
156            "summary": {
157                "type": "FIELD",
158                "field": "ERROR"
159            },
160            "location": {
161                "type": "CONSTANT",
162                "value": "Corminboeuf"
163            },
164            "source": {
165                "type": "CONSTANT",
166                "value": "root.alarm-output"
167            }
168        },
169        "ignoreUninitializedValues": true
170    }

1. Create script to generate an error

The script will throw an exception when the value is true. This will publish the error value.

root/error-generator/value.ospp

{
    "name": "Error value",
    "description": "This value will be on error when the trigger is true",
    "type": "BOOLEAN"
}

root/error-generator/output.scripts

{
    "scriptId": "root.error-generator"
}

root/error-generator/owner.scripts

{
    "moduleId": "modules.scripts.scripts-1",
    "accessedValues": [],
    "sourceFile": "root/error-generator/source.js"
}

root/error-generator/source.js

if (trigger?.content === true) {
    log.info("Generating error");
    throw new Error("Value was true");
} else {
    log.info("Generating value");
    false
}

4. Create a dashboard to change the value and visualize the alarms

root/dashboard.view

 2    "configuration": [
 3        {
 4            "valueSubscriptions": {
 5                "values": [
 6                    {
 7                        "id": "root.trigger",
 8                        "right": "READ_WRITE",
 9                        "type": "BOOLEAN"
10                    }
11                ]
12            },
13            "basicWidgetSettings": {
14                "showTooltip": true
15            },
16            "id": "-zdb_-mh",
17            "type": "BasicInputOutputValue",
18            "title": ""
19        },
20        {
21            "alarmWidgetSettings": {
22                "defaultFilter": "root.alarms.filters.all",
23                "defaultView": "root.alarms.views.default"
24            },
25            "id": "ygpJ30cw",
26            "type": "AlarmTable",
27            "title": ""
28        }
29    ],
30    "layout": {
31        "lg": [
32            {

root/dashboard.web

{
    "moduleId": "modules.web.web-1",
    "title": "Home",
    "description": "OnSphere home",
    "tags": []
}

5. Change the value and observe the new alarm appears

../_images/alarms-table-value-error-handler.png

A critical alarm is created when the value is on error.