asp.net file downloading - track downloaded size

Question

I am trying to design a system for something like this with ASP.net/C#.

The users pay for downloading some content (files- mp3s/PDFs,doc etc).I should be able to tra

Answer 1

You can easily measure data passed to the client in ASP.NET assuming you replace a direct IIS-controlled download with your own, which would go something like this:

while (context.Response.IsClientConnected) {

    bytesRead = ReadFileChunkAsByteArrayWIthOffsetOrWhatever(buffer, offset);

    context.Response.OutputStream.Write(buffer, 0, bytesRead);
    context.Response.Flush();

    offset += bytesRead;

    if (bytesRead != bufferSize)
        break;
}

It's complicated to make this 100% reliable from within ASP, but it can be done. You pretty much have to account for every possible failure point and react accordingly.

The problem though is still - as someone mentioned above - that it's impossible to know that the client received the data. If money is involved in this transaction, that can get to be a problem really quickly.

For that reason, the best approach would be to use a custom downloader client, like the one Amazon uses for MP3 file purchases. That way you're not subjecting either yourself or your customers to the vagaries of moving monetized bits over something as unreliable as HTTP.