Created Saturday 09 November 2013
If a server wants to start sending a response before knowing its total length (like with long script output), it might use the simple chunked transfer-encoding, which breaks the complete response into smaller chunks and sends them in series. You can identify such a response because it contains the Transfer-Encoding: chunked header. All HTTP 1.1 clients must be able to receive chunked messages.
A chunked message body contains a series of chunks, followed by a line with "0" (zero), followed by optional footers (just like headers), and a blank line. Each chunk consists of two parts:
- a line with the size of the chunk data, in hex, possibly followed by a semicolon and extra parameters you can ignore (none are currently standard), and ending with CRLF.
So a chunked response might look like the following:
HTTP/1.1 200 OK Date: Fri, 31 Dec 1999 23:59:59 GMT Content-Type: text/plain Transfer-Encoding: chunked 1a; ignore-stuff-here abcdefghijklmnopqrstuvwxyz 10 1234567890abcdef 0 some-footer: some-value another-footer: another-value [blank line here]