(Node.js) Streaming Download Large File to the Local Filesystem

Downloads a large file in a streaming fashion to the local filesystem.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // Azure File Service Example: Downloads a large file to the local filesystem using a Chilkat stream.
    // See:  https://docs.microsoft.com/en-us/rest/api/storageservices/get-file

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var rest = new chilkat.Rest();

    // Connect to the Azure Storage Blob Service
    var bTls = true;
    var port = 443;
    var bAutoReconnect = true;
    // In this example, the storage account name is "chilkat".
    var success = rest.Connect("chilkat.file.core.windows.net",port,bTls,bAutoReconnect);
    if (success !== true) {
        console.log(rest.LastErrorText);
        return;
    }

    // Provide Azure Cloud credentials for the REST calls.
    var azAuth = new chilkat.AuthAzureStorage();
    azAuth.AccessKey = "AZURE_ACCESS_KEY";
    // The account name used here should match the 1st part of the domain passed in the call to Connect (above).
    azAuth.Account = "chilkat";
    azAuth.Scheme = "SharedKey";
    azAuth.Service = "File";
    // This causes the "x-ms-version: 2021-08-06" header to be automatically added.
    azAuth.XMsVersion = "2021-08-06";
    success = rest.SetAuthAzureStorage(azAuth);

    // Note: The application does not need to explicitly set the following
    // headers: x-ms-date, Authorization.  These headers
    // are automatically set by Chilkat.

    // When streaming a download to the local filesystem or directed elsewhere,
    // the complete HTTP GET operation must be broken into parts.
    // For example, an HTTP GET consists of sending the request, followed by reading the response header,
    // and then finally the response body.  We'll want to read the response header, and then based
    // on the information received (such as success or failure), either read the response body
    // as an error message, or as the file data.

    // Send the HTTP GET request to download the file.
    // The share is named "pip".
    success = rest.SendReqNoBody("GET","/pip/somethingBig.zip");
    if (success !== true) {
        console.log(rest.LastErrorText);
        return;
    }

    // Read the response header.
    var responseStatusCode = rest.ReadResponseHeader();
    if (responseStatusCode < 0) {
        console.log(rest.LastErrorText);
        return;
    }

    console.log("Response status code = " + responseStatusCode);

    // We expect a 200 response status if the file data is coming.
    // Otherwise, we'll get a string response body with an error message(or no response body).
    if (responseStatusCode == 200) {

        var bodyStream = new chilkat.Stream();

        // The stream's sink will be a file.
        bodyStream.SinkFile = "qa_output/somethingBig.zip";

        // Read the response body to the stream.  Given that we've
        // set the stream's sink to a file, it will stream directly
        // to the file.
        success = rest.ReadRespBodyStream(bodyStream,true);
        if (success !== true) {
            console.log(rest.LastErrorText);
            return;
        }

        console.log("Successfully received the large file.");

    }
    else {
        var errResponse = rest.ReadRespBodyString();
        if (rest.LastMethodSuccess !== true) {
            console.log(rest.LastErrorText);
        }
        else {
            console.log(errResponse);
        }

    }


}

chilkatExample();