Pdf streaming

[dhananjay19100]

I have uploaded a few PDFs to an S3 bucket, and the PDF viewer is downloading some PDFs in chunks while others are downloaded in full before being displayed. The metadata of the PDFs and the server are also the same. Can you explain why this is happening?

pdf which is download full: https://pdf-testing.s3.ap-south-1.amazonaws.com/2gb-sample-file.pdf

[stephanrauh]

According to my documentation (https://pdfviewer.net/extended-pdf-viewer/range-requests), you need three response headers:

• "Content-Length"
• "Accept-Ranges": "bytes",
• "Content-Encoding"

Your S3 file only returns two of these three attributes. I'm not sure why Content-Encoding is necessary, but I trust I've written this because of a reason, even though I've forgotten the reason in the meantime.

[stephanrauh]

This time, Accept-Ranges seems to return null. You can debug this yourself. Set minifiedJSLibraries="false", open the file pdf-xx.js in your browser's debugger, navigate to the method validateRangeRequestCapabilities(), and set a breakpoint.

function validateRangeRequestCapabilities({
  getResponseHeader,
  isHttp,
  rangeChunkSize,
  disableRange,
}) {
  if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
    assert(
      Number.isInteger(rangeChunkSize) && rangeChunkSize > 0,
      "rangeChunkSize must be an integer larger than zero."
    );
  }
  const returnValues = {
    allowRangeRequests: false,
    suggestedLength: undefined,
  };

  const length = parseInt(getResponseHeader("Content-Length"), 10);
  if (!Number.isInteger(length)) {
    return returnValues;
  }

  returnValues.suggestedLength = length;

  if (length <= 2 * rangeChunkSize) {
    // The file size is smaller than the size of two chunks, so it does not
    // make any sense to abort the request and retry with a range request.
    return returnValues;
  }

  if (disableRange || !isHttp) {
    return returnValues;
  }
  if (getResponseHeader("Accept-Ranges") !== "bytes") {
    return returnValues;
  }

  const contentEncoding = getResponseHeader("Content-Encoding") || "identity";
  if (contentEncoding !== "identity") {
    return returnValues;
  }

  returnValues.allowRangeRequests = true;
  return returnValues;
}

[dhananjay19100]

how i can run your code in my system

[stephanrauh]

Please elaborate. Which code do you want to run, and why?

[dhananjay19100]

to check validateRangeRequestCapabilities() methode for chunking

[stephanrauh]

That's not my code. It's the source code of pdf.js.

[dhananjay19100]

In you new version 19.0.3, '[(page)]="pageNumber" method is not working

[dhananjay19100]

it always open 1st page

[stephanrauh]

What? But you're right, my showcase demo almost always shows page 1 instead of page 5. Weird. I've opened a dedicated ticket.