Streamming from Browser

Question:

When we stream a big file to the server, what is happening inside the browser? Are all the data chunks sent within a single POST request? Or each chunk is sent by an individual POST request and the whole file is streamed by sending multiple POST requests?


Answer:

No need to do multiple POSTs, the browser takes care of that for you. If you’re uploading a file you use a <input type="file" /> HTML control and the very important <form enctype="multipart/form-data" method="POST">

The multipart/form-data attribute value on a <form> tells the browser to split up the binary data (your file) into chunks and sent up the stream one at a time. multipart/form-data is a MIME type and all browsers are coded to handle it as a chunked stream of binary data.

See more here in the specification:
http://www.w3.org/TR/html401/interact/forms.html#h-17.13.4.2