Download large file with progress

How can I download a file from a web service and save it on a file while getting progress on the download? Could Chunks be used?


  • edited November 2015 Answer ✓

    Daniel -

    The KinomaJS Handler prototype provides a download function for downloading files with progress. You can wrap like this in a local behavior:

    Handler.Bind("/download", class extends Behavior {
        onComplete(handler, message) {
            if (0 == message.error && 200 == message.status)
                trace("Download complete!\n");
        onInvoke(handler, message) {
            let query = parseQuery(message.query);
   Message(query.url), query.file);
        onProgress(handler, message, offset, size) {
            trace("Downloaded " + offset + " of " + size + "\n");
            application.distribute("onDownloadProgress", offset, size);

    Then call the download handler like this from a container:

    let uri = "/download?" + serializeQuery({
        file:mergeURI(Files.temporaryDirectory, "download")
    container.invoke(new Message(uri));

    In the example above, the progress function distributes an onDownloadProgress event that can be implemented by the container's behavior to update a progress indicator. The file is downloaded to the temporary items directory.

    Regards, Brian

  • Follow up question: How can I cancel an active download?

  • Daniel -

    To cancel an active download you can cancel the message that triggered the download:

    let uri = "/download?" + serializeQuery({
        file:mergeURI(Files.temporaryDirectory, "download")
    this.message = new Message(uri);
    // cancel the active download
  • edited November 2015

    Kinoma seems to have some problems requesting objects from AWS S3 using pre-signed URLS. Has anybody seen this before? Here's an example of such URL:; filename="test.txt"&X-Amz-Content-Sha256=e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=/20151117/us-east-1/s3/aws4_request&X-Amz-Date=20151117T215521Z&X-Amz-SignedHeaders=Host&X-Amz-Expires=300&X-Amz-Signature=0da4d2fd4032e0dbe20ad9fd3b2a8d21f252810e99a93c9b7af41abba7cc5e58

    This URL has been edited and was only signed for 5 minutes so it won't work as such. It's only provided as sample. When copying into the browser (within 5 minute of its creation), the file starts to download with no problems. If sending it using "", the server responds with

    Http Status: 403

    Code: SignatureDoesNotMatch

    Message: The request signature we calculated does not match the signature you provided. Check your key and signing method.

    I can't think of anything else than Kinoma changing something just before sending. Maybe a problem with encoding/decoding... Or a wrong "host" request header?

    any ideas?

  • Daniel,

    To confirm the URL isn't being truncated for some reason, can you retry this request, but move the "X-Amz-Signature" variable earlier in the request string? I think placing it between the "X-Amz-Content-Sha256" and "X-Amz-Algorithm" variables would produce a meaningful result. If truncation is occurring, I would expect S3 to respond with a different 403 Code corresponding to whatever got cut off.

    Thanks, Will

  • No changes in the response. Same exact error

  • I don't know if this helps but I added an endpoint on my server that responds with a redirect to the signed URL. I tried to call that endpoint instead of trying to call the signed URL directly from Kinoma. The result is the same as indicated above.

  • Daniel,

    The URL you're using has an un-encoded space in it after "disposition=attachment;". Please try replacing that space with "%20" and retesting.

    Let me know if that makes a difference.


  • It didn't help. I also removed the whole content-disposition part as it's not needed for this download and it made no difference.

  • edited November 2015


    There are a number of headers that KinomaJS's HTTP stack doesn't set automatically. It is possible that Amazon is looking for one of these and failing without it.

    In my testing, using a Firefox request as a benchmark, headers not set include:


    To set these headers, the Message object has a setRequestHeader() method, as shown below:

     let msg = new Message(uri);
     msg.setRequestHeader("User-Agent", "KinomaJS Application")



  • edited November 2015

    The only header required (i.e. used in the signature) as far as I know is host which I think might be the culprit, as Kinoma passes it like this: and I think the server calculated the signature using

    According to the AWS Signature specs when the port is standard (80 for HTTP and 443 for HTTPS) the port should be omitted.

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