introduction

this package provides an implementation of the OPCUA File Transfer specification as per OPCUA 1.0.4 part 5 Annex C (page 99)

installation

$ npm install node-opcua
$ npm install node-opcua-file-transfer
Copy

exposing a File node in the addressSpace

import { OPCUAServer, UAFile } from "node-opcua";
import { installFileType } from "node-opcua-file-transfer";

Copy

const server = new OPCUAServer({

});

await server.initialize();


// let say we want to create a access to this file:
const my_data_filename = "/data/someFile.txt";
await promisify(fs.writeFile)(my_data_filename, "some content", "utf8");


// now add a file object in the address Space
const addressSpace = server.engine.addressSpace;

// retrieve the FileType UAObjectType
const fileType = addressSpace.findObjectType("FileType")!;

// create a instance of FileType 
const myFile = fileType.instantiate({
    nodeId: "s=MyFile",
    browseName: "MyFile",
    organizedBy: addressSpace.rootFolder.objects
}) as UAFile;

// now bind the opcuaFile object with our file
installFileType(opcuaFile, { 
    filename: my_data_filename
});

Copy

accessing a File node from a node-opcua client : ClientFile

We assume that we have a valid OPCUA Client Session

import { OPCUAClient } from "node-opcua";
import { ClientFile } from "node-opcua-file-transfer";

const client = OPCUAClient.create({});

await client.connect();
const session = await client.createSession();
Copy

Let's assume that the nodeId of the file object is "ns=1;s=MyFile"

import {ClientFile,OpenFileMode } from "node-opcua-file-transfer";

// 
const fileNodeId = "ns=1;s=MyFile";

// let's create a client file object from the session and nodeId
const clientFile = new ClientFile(session, fileNodeId);

// let's open the file
const mode = OpenFileMode.ReadWriteAppend;
await clientFile.open(mode);

// ... do some reading or writing

// don't forget to close the file when done
await clientFile.close();
Copy

operations

ClientFile#size(): Promise : get file size

You can read the size of the file at any time.

const clientFile = new ClientFile(session, fileNodeId);

const size = await clientFile.size();
console.log("the current file size is : ",size," bytes);
Copy

ClientFile#open(mode: OpenFileMode) : open a file

const mode = OpenFileMode.ReadWriteAppend;
await clientFile.open(mode);
Copy

OpenFileMode enumeration

ClientFile#close() : close a file

const mode = OpenFileMode.ReadWriteAppend;
await clientFile.open(mode);

// ... do some reading or writing

// don't forget to close the file when done
await clientFile.close();
Copy

ClientFile#setPosition(pos: UInt64) : Setting read/write position

Once the file is opened, the position for reading or writing can be set using setPosition.

• setPosition expect a UInt64 parameter (see note below)
• setPosition will throw an exception if file is not opened

const clientFile = new ClientFile(session, fileNodeId);

const mode = OpenFileMode.ReadWriteAppend;
await clientFile.open(mode);

await client.setPosition([0,32]);

Copy

ClientFile#getPosition(): Promise Getting read/write position

Once the file is opened, the position for reading or writing can be retrieved using getPosition.

• getPosition returns a UInt64 parameter (see note below)
• getPosition will throw an exception if file is not opened

const clientFile = new ClientFile(session, fileNodeId);

const mode = OpenFileMode.ReadWriteAppend;
await clientFile.open(mode);

await client.setPosition(32);

Copy

ClientFile#write(buf: Buffer) : Writing data to the file

Data can be writing to the file at the current cursor position. Data must be passed in a buffer.

• write will throw an exception if file is not opened

const dataToWrite = Buffer.from("Some data");

const mode = OpenFileMode.ReadWriteAppend;
await clientFile.open(mode);
await clientFile.write(dataToWrite);
Copy

ClientFile#read(): Promise :reading data to the file

Data can be written to the file at the current cursor position. Data must be passed in a buffer.

• read will throw an exception if the file is not opened

const mode = OpenFileMode.ReadWriteAppend;
await clientFile.open(mode);

// read 200 bytes from position 32
await clientFile.setPosition([0,32]);
const data: Buffer = await clientFile.read(200);
Copy

notes

UInt64

• At this time BigInt, is not supported by all versions of nodeJs that are targeted by node-opcua. UInt64 values are currently stored into an array of 2 32bits numbers : [ High,Low]

Feature

Sponsors & Backers

We appreciate that, once you have evaluated the software you consider supporting our effort by applying to our sponsor program:

• https://github.com/sponsors/node-opcua
• https://opencollective.com/node-opcua

Grants ensure the following:

• 🔨 Long term maintenance of the project
• ⚙️ maintain the website and continuous integration platform
• 🛣 Progress on the road-map
• 🐛 Quick responses to bug reports
• 🚀 New features & enhancements
• ⚖️ representing the node-opcua user community at the OPC Foundation

Support

Technical Support is exclusively provided to registered members of the NodeOPCUA Subscription (https://support.sterfive.com) or through dedicated Professional Services.

License

Node-OPCUA is made available to you under the MIT open source license.

See LICENSE for details.

value-added extensions

Contact Sterfive SAS (mailto:contact@sterfive.com) for additional companion modules that are available to registered members:

• node-opcua-pub-sub : Part 14 implementation to develop OPC UA PubSub over MQTT applications
• node-opcua-webproxy: to operate node-opcua from within a web browser
• node-opcua-optimized-client: super-charge OPC UA Client
• react-components: a collection of React UI components
• aggregator: a powerful OPC UA aggregator that can combine and monitored hundred of servers and millions of variables.
• node-opcua-gds: a Global Discovery Server (Part 12)
• node-opcua-modeler-ex: a powerful NO-GUI OPC UA modeler

Copyright

Copyright (c) 2022-2024 Sterfive SAS - https://www.sterfive.com

Copyright (c) 2014-2022 Etienne Rossignon