node-epics-pcas

v0.1.1

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10 months ago

EPICS Portable Channel Access Server for Node.js

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wanglin86769

EPICS Channel Access CAS PCAS Node.js JavaScript FFI

EPICS Portable Channel Access Server for Node.js

node-epics-pcas is an EPICS PCAS library for Node.js, it is a FFI wrapper that talks to the PCAS shared library using a third-party Node.js FFI package called koffi.

This project is inspired by pcaspy in the following link and the implementation is very similar to pcaspy, the main difference is that most of the logic has been moved from the scripting language to C++.

https://github.com/paulscherrerinstitute/pcaspy

The implementation of node-epics-pcas is to build a wrapper into the PCAS shared library and provide C interface to Node.js, and then call the C interface from Node.js using koffi.

Alt text

Requirements

A recent Node.js version is required and the following versions have been tested,

Node.js 14.21.3
Node.js 15.14.0
Node.js 16.19.0
Node.js 17.9.1
Node.js 18.13.0

Supported platforms

Windows x86_64
Linux x86_64
macOS x86_64

Installation

npm install node-epics-pcas

Usage

The following APIs are provided for Node.js applications to create PCAS server and interact with the parameter library.

createServer()
getParam()
setParam()
setParamStatus()
updatePVs()
setDebugLevel()

Create the PCAS server

function createServer(pvList, read, write)

pvList: PV list
read: the read function for PV whose scan field is greater than 0 and soft field is false
write: the write function for PV whose soft field is false

Following is the description of PV fields,

| Field | Required | Default | Description | |--------|----------|---------|-------------| | name | Yes | | | | type | | 'float' | 'int', 'float', 'double', 'string' or 'enum' | | count | | 1 | | | scan | | 0 | | | enums | | [] | | | states | | [] | | | prec | | 0 | | | unit | | '' | | | hilim | | 0 | High limit | | lolim | | 0 | Low limit | | high | | 0 | | | low | | 0 | | | hihi | | 0 | | | lolo | | 0 | | | mdel | | 0 | | | adel | | 0 | | | soft | | true | when set to false, read or write function can be used | | value | | 0 or '' | |

Get data from the parameter library

function getParam(name)

Set data to the parameter library

function setParam(name, data)

Set alarm and severity to the parameter library

function setParamStatus(name, alarm, severity)

Post event to monitor clients when value or alarm status changes

function updatePVs()

Set debug level to print more information

function setDebugLevel(level)

Level 0: Default level, only print error information.
Level 1: Print PV definition, PV list, parameter library and scan thread.
Level 2: Print PV process information.

Examples

1. Create a dummy PV

const PCAS = require('node-epics-pcas');

const pvList = [
    { name: 'test:dummy' }
];

PCAS.createServer(pvList);

2. Create dummy scalar PVs

const PCAS = require('node-epics-pcas');

const pvList = [
    { name: 'test:dummy01', type: 'int' },
    { name: 'test:dummy02', type: 'float' },
    { name: 'test:dummy03', type: 'double' },
    { name: 'test:dummy04', type: 'string' },
    { name: 'test:dummy05', type: 'enum', enums: ['Stop', 'Run'] }
];

PCAS.createServer(pvList);

3. Create dummy array PVs

const PCAS = require('node-epics-pcas');

const pvList = [
    { name: 'test:dummy01', type: 'int', count: 5 },
    { name: 'test:dummy02', type: 'float', count: 5 },
    { name: 'test:dummy03', type: 'double', count: 5 },
    { name: 'test:dummy05', type: 'enum', count: 5, enums: ['Stop', 'Run'] }
];

PCAS.createServer(pvList);

4. Read data from Node.js

const PCAS = require('node-epics-pcas');

const pvList = [
    { name: 'test:dummy01', type: 'int', count: 1, scan: 1, soft: false },
    { name: 'test:dummy02', type: 'float', count: 1, scan: 1, soft: false },
    { name: 'test:dummy03', type: 'double', count: 1, scan: 1, soft: false },
    { name: 'test:dummy04', type: 'int', count: 5, scan: 1, soft: false },
    { name: 'test:dummy05', type: 'float', count: 5, scan: 1, soft: false },
    { name: 'test:dummy06', type: 'double', count: 5, scan: 1, soft: false },
];

function read(name) {
    let value;
    if(name === 'test:dummy01') {
        value = Math.random() * 100;
    }
    if(name === 'test:dummy02') {
        value = Math.random();
    }
    if(name === 'test:dummy03') {
        value = Math.random() * 0.01;
    }
    if(name === 'test:dummy04') {
        value = [Math.random() * 100, Math.random() * 100, Math.random() * 100, Math.random() * 100, Math.random() * 100];
    }
    if(name === 'test:dummy05') {
        value = [Math.random(), Math.random(), Math.random(), Math.random(), Math.random()];
    }
    if(name === 'test:dummy06') {
        value = [Math.random() * 0.01, Math.random() * 0.01, Math.random() * 0.01, Math.random() * 0.01, Math.random() * 0.01];
    }
    return value;
}

PCAS.createServer(pvList, read, null);

5. Write data to Node.js

const PCAS = require('node-epics-pcas');

const pvList = [
    { name: 'test:dummy01', type: 'int', count: 1, soft: false },
    { name: 'test:dummy02', type: 'float', count: 1, soft: false },
    { name: 'test:dummy03', type: 'double', count: 1, soft: false },
    { name: 'test:dummy04', type: 'int', count: 5, soft: false },
    { name: 'test:dummy05', type: 'float', count: 5, soft: false },
    { name: 'test:dummy06', type: 'double', count: 5, soft: false},
];

let data = {};

function write(name, value) {
    if(name === 'test:dummy01') {
        data['dummy01'] = value;
    }
    if(name === 'test:dummy02') {
        data['dummy02'] = value;
    }
    if(name === 'test:dummy03') {
        data['dummy03'] = value;
    }
    if(name === 'test:dummy04') {
        data['dummy04'] = value;
    }
    if(name === 'test:dummy05') {
        data['dummy05'] = value;
    }
    if(name === 'test:dummy06') {
        data['dummy06'] = value;
    }
}

PCAS.createServer(pvList, null, write);

setInterval(() => {
    console.log(data);
}, 10000);

6. Raise alarm automatically

const PCAS = require('node-epics-pcas');

const pvList = [
    {
        name: 'test:dummy01',
        type: 'int',
        count: 1,
        scan: 1,
        high: 60,
        low: 40,
        hihi: 80,
        lolo: 20,
        soft: false
    }
];

function read(name) {
    let value;
    if(name === 'test:dummy01') {
        value = Math.random() * 100;
    }
    return value;
}

PCAS.createServer(pvList, read, null);

7. Raise alarm manually

const PCAS = require('node-epics-pcas');

const pvList = [
    { name: 'test:dummy01', type: 'int', count: 1 }
];

PCAS.createServer(pvList);

setInterval(() => {
    const name = 'test:dummy01';
    let value = PCAS.getParam(name);
    if(value >= 80) {
        PCAS.setParamStatus(name, PCAS.Alarm.HIHI_ALARM, PCAS.Severity.MAJOR_ALARM);
    } else if(value <= 20) {
        PCAS.setParamStatus(name, PCAS.Alarm.LOLO_ALARM, PCAS.Severity.MAJOR_ALARM);
    } else if(value >= 60) {
        PCAS.setParamStatus(name, PCAS.Alarm.HIGH_ALARM, PCAS.Severity.MINOR_ALARM);
    } else if(value <= 40) {
        PCAS.setParamStatus(name, PCAS.Alarm.LOW_ALARM, PCAS.Severity.MINOR_ALARM);
    }
    PCAS.updatePVs();
    PCAS.setParam(name, value + 1);
    PCAS.updatePVs();
}, 500);

8. Publish Archiver Appliance status as EPICS PV

const PCAS = require('node-epics-pcas');
const axios = require('axios');

const ARCHIVER_URL = 'http://192.168.1.100:17665'
const GET_INSTANCE_METRICS_URL = ARCHIVER_URL + '/mgmt/bpl/getInstanceMetrics'
const GET_STORAGE_METRICS_FOR_APPLIANCE_URL = ARCHIVER_URL + '/mgmt/bpl/getStorageMetricsForAppliance?appliance=appliance0'
const REQUEST_TIMEOUT = 5

const pvList = [
    { name: 'Test:status',                      type: 'string', value: '' },
    { name: 'Test:MGMT_uptime',                 type: 'string', value: '' },
    { name: 'Test:pvCount',                     type: 'int',    value: 0 },
    { name: 'Test:connectedPVCount',            type: 'int',    value: 0 },
    { name: 'Test:disconnectedPVCount',         type: 'int',    value: 0 },
    { name: 'Test:dataRateGBPerDay',            type: 'float',  prec: 2, unit: 'GB/day', value: 0 },
    { name: 'Test:sts_total_space',             type: 'float',  prec: 2, unit: 'GB',     value: 0 },
    { name: 'Test:sts_available_space',         type: 'float',  prec: 2, unit: 'GB',     value: 0 },
    { name: 'Test:sts_available_space_percent', type: 'float',  prec: 2, unit: '%',      value: 0 },
    { name: 'Test:mts_total_space',             type: 'float',  prec: 2, unit: 'GB',     value: 0 },
    { name: 'Test:mts_available_space',         type: 'float',  prec: 2, unit: 'GB',     value: 0 },
    { name: 'Test:mts_available_space_percent', type: 'float',  prec: 2, unit: '%',      value: 0 },
    { name: 'Test:lts_total_space',             type: 'float',  prec: 2, unit: 'GB',     value: 0 },
    { name: 'Test:lts_available_space',         type: 'float',  prec: 2, unit: 'GB',     value: 0 },
    { name: 'Test:lts_available_space_percent', type: 'float',  prec: 2, unit: '%',      value: 0 },
];

PCAS.createServer(pvList);

function alarmInstanceMetrics() {
    PCAS.setParamStatus('Test:status', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:MGMT_uptime', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:pvCount', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:connectedPVCount', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:disconnectedPVCount', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:dataRateGBPerDay', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.updatePVs();
}

function alarmStorageMetrics() {
    PCAS.setParamStatus('Test:sts_total_space', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:sts_available_space', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:sts_available_space_percent', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:mts_total_space', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:mts_available_space', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:mts_available_space_percent', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:lts_total_space', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:lts_available_space', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.setParamStatus('Test:lts_available_space_percent', PCAS.Alarm.TIMEOUT_ALARM, PCAS.Severity.MINOR_ALARM);
    PCAS.updatePVs();
}

// Poll archiver appliance status
async function pollArchiverStatus() {

    // Get instance metrics data
    try {
        let response = await axios.get(GET_INSTANCE_METRICS_URL);
        if(!response || !response.data || !response.status) {
            console.log('Instance metrics data is not obtained from the Archiver Appliance server');
            alarmInstanceMetrics();
            return;
        }
        let data = response.data[0];
        console.log(data);

        let status = data['status'];  // string
        let MGMT_uptime = data['MGMT_uptime'];  // string
        let pvCount = Number(data['pvCount']);  // int
        let connectedPVCount = Number(data['connectedPVCount']);  // int
        let disconnectedPVCount = Number(data['disconnectedPVCount']);  // int
        let dataRateGBPerDay = Number(data['dataRateGBPerDay']);  // float

        PCAS.setParam('Test:status', status);
        PCAS.setParam('Test:MGMT_uptime', MGMT_uptime);
        PCAS.setParam('Test:pvCount', pvCount);
        PCAS.setParam('Test:connectedPVCount', connectedPVCount);
        PCAS.setParam('Test:disconnectedPVCount', disconnectedPVCount);
        PCAS.setParam('Test:dataRateGBPerDay', dataRateGBPerDay);
        PCAS.updatePVs();
    } catch(error) {
        console.log('axios request failed');
        alarmInstanceMetrics();
    }

    // Get storage metrics data
    try {
        let response = await axios.get(GET_STORAGE_METRICS_FOR_APPLIANCE_URL);
        if(!response || !response.data || !response.status) {
            console.log('Storage metrics data is not obtained from the Archiver Appliance server');
            alarmStorageMetrics();
            return;
        }
        let data = response.data;
        console.log(data);

        let sts_total_space;
        let sts_available_space;
        let sts_available_space_percent;
        let mts_total_space;
        let mts_available_space;
        let mts_available_space_percent;
        let lts_total_space;
        let lts_available_space;
        let lts_available_space_percent;
        for(let item of data) {
            if(item['name'] === 'STS') {
                sts_total_space = Number(item['total_space'].replace(',', ''));
                sts_available_space = Number(item['available_space'].replace(',', ''));
                sts_available_space_percent = Number(item['available_space_percent'].replace(',', ''));
            }
            if(item['name'] === 'MTS') {
                mts_total_space = Number(item['total_space'].replace(',', ''));
                mts_available_space = Number(item['available_space'].replace(',', ''));
                mts_available_space_percent = Number(item['available_space_percent'].replace(',', ''));
            }
            if(item['name'] === 'LTS') {
                lts_total_space = Number(item['total_space'].replace(',', ''));
                lts_available_space = Number(item['available_space'].replace(',', ''));
                lts_available_space_percent = Number(item['available_space_percent'].replace(',', ''));
            }
        }

        PCAS.setParam('Test:sts_total_space', sts_total_space);
        PCAS.setParam('Test:sts_available_space', sts_available_space);
        PCAS.setParam('Test:sts_available_space_percent', sts_available_space_percent);
        PCAS.setParam('Test:mts_total_space', mts_total_space);
        PCAS.setParam('Test:mts_available_space', mts_available_space);
        PCAS.setParam('Test:mts_available_space_percent', mts_available_space_percent);
        PCAS.setParam('Test:lts_total_space', lts_total_space);
        PCAS.setParam('Test:lts_available_space', lts_available_space);
        PCAS.setParam('Test:lts_available_space_percent', lts_available_space_percent);
        PCAS.updatePVs();
    } catch(error) {
        console.log('axios request failed');
        alarmStorageMetrics();
    }
}

setInterval(pollArchiverStatus, REQUEST_TIMEOUT * 1000);

License

MIT license

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Readme

EPICS Portable Channel Access Server for Node.js

Requirements

A recent Node.js version is required and the following versions have been tested,

Supported platforms

Installation

Usage

Create the PCAS server

Get data from the parameter library

Set data to the parameter library

Set alarm and severity to the parameter library

Post event to monitor clients when value or alarm status changes

Set debug level to print more information

Examples

1. Create a dummy PV

2. Create dummy scalar PVs

3. Create dummy array PVs

4. Read data from Node.js

5. Write data to Node.js

6. Raise alarm automatically

7. Raise alarm manually

8. Publish Archiver Appliance status as EPICS PV

License