Node.js

SFTP Upload Large File in Parts

See more SFTP Examples

Demonstrates how to split a large file into N parts and then upload each part separately. This technique can be used to potentially avoid limits a SFTP server might impose on upload file size. Node.js

NODEJS_PRELUDE

function chilkatExample() {

    var success = false;

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

    var sftp = new chilkat.SFtp();

    //  Set some timeouts, in milliseconds:
    sftp.ConnectTimeoutMs = 5000;
    sftp.IdleTimeoutMs = 10000;

    //  Connect to the SSH server.  
    //  The standard SSH port = 22
    //  The hostname may be a hostname or IP address.
    var hostname = "sftp.example.com";
    var port = 22;
    success = sftp.Connect(hostname,port);
    if (success !== true) {
        console.log(sftp.LastErrorText);
        return;
    }

    //  Authenticate with the SSH server.  Chilkat SFTP supports
    //  both password-based authenication as well as public-key
    //  authentication.  This example uses password authenication.
    success = sftp.AuthenticatePw("myLogin","myPassword");
    if (success !== true) {
        console.log(sftp.LastErrorText);
        return;
    }

    //  After authenticating, the SFTP subsystem must be initialized:
    success = sftp.InitializeSftp();
    if (success !== true) {
        console.log(sftp.LastErrorText);
        return;
    }

    //  Open a remote file for writing on the SSH server.
    //  If the file already exists, it is overwritten.
    //  (Specify "createNew" instead of "createTruncate" to
    //  prevent overwriting existing files.)
    var handle = sftp.OpenFile("big.zip","writeOnly","createTruncate");
    if (sftp.LastMethodSuccess !== true) {
        console.log(sftp.LastErrorText);
        return;
    }

    //  We're going to upload the local file "qa_data/zips/big.zip" (a relative local path from our current working directory)
    //  to the SFTP server.
    var localFilePath = "qa_data/zips/big.zip";

    //  Rather than uploading in one shot, we'll read the local file in chunks
    //  and upload a chunk at a time.
    var fac = new chilkat.FileAccess();

    success = fac.OpenForRead(localFilePath);
    if (success == false) {
        sftp.CloseHandle(handle);
        console.log(fac.LastErrorText);
        return;
    }

    //  If we were to split the local file into 128K chunks, how many chunks (blocks) would
    //  we have, including the last partial block?
    var blockSize = 131072;
    var numBlocks = fac.GetNumBlocks(blockSize);
    console.log("Number of blocks = " + numBlocks);

    var bd = new chilkat.BinData();
    var i = 0;
    while (i < numBlocks) {
        //  Read the Nth block, which gets appended to the bd.  (which means
        //  we must clear the contents of bd before the next iteration)
        success = fac.ReadBlockBd(i,blockSize,bd);
        if (success == false) {
            sftp.CloseHandle(handle);
            console.log(fac.LastErrorText);
            return;
        }

        //  Upload this block to the open remote file.
        success = sftp.WriteFileBd(handle,bd);
        if (success == false) {
            console.log(sftp.LastErrorText);
            return;
        }

        //  Clear the contents for the next iteration.
        bd.Clear();

        i = i+1;
    }

    //  Close the local file.
    fac.FileClose();

    //  -----------------------------------------------------------------------------
    //  This is important.  You must close the handle on the server.
    //  Otherwise open handles will accumulate on the server until eventually a limit
    //  is reached and the server will fail on a call to OpenFile.
    //  -----------------------------------------------------------------------------

    //  Close the remote file handle on the server.
    success = sftp.CloseHandle(handle);
    if (success !== true) {
        console.log(sftp.LastErrorText);
        return;
    }

    console.log("Success.");

}

chilkatExample();