Guide: Using the API

Learn how to use the atscm API to e.g. run server serverscripts in your node application. Available since atscm v1.0.0. Use atscm update to use the latest version

Installation

First of all, make sure your project has atscm installed: Take a look at your package.json file and make sure, atscm is present in the dependencies or (depending on your use case) devDependencies section. Otherwise, install atscm if necessary:

# If you need atscm as a runtime-dependency
npm install --save atscm

# If you need atscm as a development dependency (most likely)
npm install --save-dev atscm

Configuration

Similar to regular atscm projects, you need an Atviseproject file that contains atscm's configuration. A minimal example may look like this:

// Atviseproject.js
const { Atviseproject } = require('atscm');

module.exports = class ApiProject extends Atviseproject {
  // Add your configuration here, if needed.
  // By default, atvise server is assumed to run on opc.tcp://localhost:4840
};

Before you can finally require the atscm API in your project, you have to set the ATSCM_CONFIG_PATH environment variable, pointing to your Atviseproject file. You can do this in multiple ways:

• You can set it in your app at runtime (recommended)

  Adjust your app's entry file (assuming it's called app.js in these examples) to set the variable before you import atscm:

  // app.js
  const { join } = require('path');
  
  process.env.ATSCM_CONFIG_PATH = join(__dirname, '../Atviseproject.js');
  
  // Your app comes here...
  

• You can set it every time you run your application:

  E.g. instead of running your app with node ./app.js you can use ATSCM_CONFIG_PATH="/my-project/Atviseproject.js" node ./app.js.

  You can also use npm scripts so you simply have to run npm run start:

  // package.json
  {
    "scripts": {
      "start": "ATSCM_CONFIG_PATH='/my-project/Atviseproject.js' node ./app.js"
    }
  }
  

  If your running on windows, use cross-env to set the environment variable (don't forget npm install cross-env):

  // package.json
  {
    "scripts": {
      "start": "cross-env ATSCM_CONFIG_PATH='/my-project/Atviseproject.js' node ./app.js"
    }
  }
  

Usage

Require atscm/api and call the methods you need:

// Set process.env.ATSCM_CONFIG_PATH here...

const atscm = require('atscm/api');

// You can use atscm here...

Examples

Create an export file for a node

// app.js

// Import node core modules
const { promises: fsp } = require('fs');
const { join, dirname } = require('path');

// Set atscm config env variable
process.env.ATSCM_CONFIG_PATH = join(__dirname, './Atviseproject.js');

// Require atscm and node-opcua APIs
const { NodeId } = require('atscm');
const { callMethod } = require('atscm/api');
const { Variant, DataType, VariantArrayType } = require('node-opcua');

// Configuration: You could also use process.argv here...
const nodesToExport = ['AGENT.DISPLAYS.Main'];
const exportPath = './out/export.xml';

// Our main function
async function createExportFile() {
  console.log(`Exporting nodes: ${nodesToExport.join(',')}`);

  // Use the 'exportNodes' method to create an xml export on the server
  const {
    outputArguments: [{ value }],
  } = await callMethod(new NodeId('AGENT.OPCUA.METHODS.exportNodes'), [
    new Variant({
      dataType: DataType.NodeId,
      arrayType: VariantArrayType.Array,
      value: nodesToExport.map((id) => new NodeId(id)),
    }),
  ]);

  // Create the output directory if needed
  await fsp.mkdir(dirname(exportPath), { recursive: true });

  // Write the export to the file
  await fsp.writeFile(exportPath, value);

  console.log(`Export written to ${exportPath}`);
}

// Run it and catch any errors
createExportFile().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});

Note: The example assumes the Atviseproject file is located in the same directory as the app's entry file. Otherwise you have to adjust you code accordingly.