JavaScript Barcode SDK: Native vs. WebAssembly

A JavaScript barcode SDK can be built in C/C++ for high performance. We can compile C/C++ code to a Node.js addon or WebAssembly. Which one is superior? Let’s try Dynamsoft Barcode Reader SDK to find the answer.

Node.js C++ Addon vs. WebAssembly

Speed

Performance is vital for SDK. According to our common sense, C++ addon should be the winner. However, it is interesting to see the performance gap when running C++ addon and WebAssembly in Node.js app.

Build C++ addon for Node.js

Download Dynamsoft Barcode Reader 6.2. You can choose one edition of Windows, Linux, and macOS. Here I use the Linux edition.

Get the sample code.

Copy libDynamsoftBarcodeReaderx64.so to /usr/lib:

sudo cp <Your PATH>/libDynamsoftBarcodeReaderx64.so /usr/lib/libDynamsoftBarcodeReader.so

Install node-gyp:

npm install -g node-gyp

Configure the building environment:

node-gyp configure

Build the extension:

node-gyp build

Install WebAssembly barcode SDK

npm install dbrjs

Create a simple Node.js barcode reader

var dbr = require('./build/Release/dbr');
var Module = require('dbrjs');
function decodeFileStreamAsync(fileName) {
let stats = fs.statSync(fileName);
let fileSize = stats["size"];
fs.open(fileName, 'r', function(status, fd) {
if (status) {
console.log(status.message);
return;
}
var source = fs.readFileSync(fileName);
var typedArray = new Uint8Array(source);
Module.onRuntimeInitialized = function() {
let dbr = new Module.BarcodeReaderWasm("t0068NQAAAKTSQDbEid8CTEeNluhTXi+h35G8R03xIHsyYNzZoa2GiU2a8y7s5Z1lfHsMW5dNyZmH6jQL51HUcoB5EhpDeDk=");
console.time('wasm');
let results = dbr.DecodeFileInMemory(typedArray, "");
console.timeEnd('wasm');
let json = JSON.parse(results);
let barcodeResults = json['textResult'];
let txts = [];
for (let i = 0; i < barcodeResults.length; ++i) {
console.log("Value : " + Buffer.from(barcodeResults[i].BarcodeText, 'base64').toString('ascii'));
}
console.log("Done............................................................\n");
};
let buffer = new Buffer(fileSize);
fs.read(fd, buffer, 0, fileSize, 0, function(err, bytesRead, data) {
console.time('native');
dbr.decodeFileStreamAsync(buffer, fileSize, barcodeTypes, function(err, msg) {
console.timeEnd('native');
let result = null;
for (index in msg) {
result = msg[index];
// console.log("Format: " + result['format']);
console.log("Value : " + result['value']);
}
console.log("Done............................................................\n");
}, "");
});
});
}

Run the app to check the results.

It turns out Node.js C++ addon is much faster than WebAssembly.

Portability

Although C++ addon has excellent performance, you have to use different compilers to rebuild it on different platforms. In contrast with C++ addon, WebAssembly is portable. If you have a Linux subsystem installed in Windows, you can quickly test the Node.js barcode reader by switching Linux and Windows.

Web app development

Node.js C++ addon can only work on server-side, whereas WebAssembly can work on both server-side and client-side. To create an HTML5 barcode reader for web browsers, you can either implement a RESTful web service with C++ addon or build it with WebAssembly SDK.

Example: How to Use Dynamsoft WebAssembly Barcode SDK

Node.js

Create index.js:

const fs = require('fs');
var source = fs.readFileSync('test.jpg');
var typedArray = new Uint8Array(source);
const Module = require('dbrjs');
Module.onRuntimeInitialized = function() {
let dbr = new Module.BarcodeReaderWasm("t0068NQAAAKTSQDbEid8CTEeNluhTXi+h35G8R03xIHsyYNzZoa2GiU2a8y7s5Z1lfHsMW5dNyZmH6jQL51HUcoB5EhpDeDk=");
console.time('wasm');
let results = dbr.DecodeFileInMemory(typedArray, "");
console.timeEnd('wasm');
let json = JSON.parse(results);
let barcodeResults = json['textResult'];
let txts = [];
for (let i = 0; i < barcodeResults.length; ++i) {
txts.push(Buffer.from(barcodeResults[i].BarcodeText, 'base64').toString('ascii'));
}
console.log(txts.join(", "));
};

Run the app:

node index.js

Web

var reader;
c.onRuntimeInitialized = function () {
document.getElementById('anim-loading').style.display = 'none';
buttonFile.disabled = false;
buttonVideo.disabled = false;
reader = new c.BarcodeReaderWasm("t0068NQAAAKTSQDbEid8CTEeNluhTXi+h35G8R03xIHsyYNzZoa2GiU2a8y7s5Z1lfHsMW5dNyZmH6jQL51HUcoB5EhpDeDk=");
};
if (reader) {
try {
// results = reader.DecodeBuffer(idd.buffer, imageWidth, imageHeight, imageWidth * 4, 7, "");
let results = reader.DecodeFileInMemory(arrayBuffer, "");
let json = JSON.parse(results);
let barcodeResults = json['textResult'];
let txts = [];
for (let i = 0; i < barcodeResults.length; ++i) {
txts.push(b64DecodeUnicode(barcodeResults[i].BarcodeText));
}
barcode_result.textContent = txts.join(", ");
} catch (e) {
console.log(e);
}
}

Conclusion

If you pursue extreme performance for Node.js, choose C++ addon. If the performance gap is not a big deal for you, WebAssembly is no doubt the best choice.

License

Get the trial license.

Source Code

https://github.com/dynamsoft-dbr/webassembly


Originally published at www.codepool.biz on August 6, 2018.