Prevent Apache from chunking gzipped content

Question

When using mod_deflate in Apache2, Apache will chunk gzipped content, setting the Transfer-encoding: chunked header. While this results in a faster download time, I cannot display a progress bar.

If I handle the compression myself in PHP, I can gzip it completely first and set the Content-length header, so that I can display a progress bar to the user.

Is there any setting that would change Apache's default behavior, and have Apache set a Content-length header instead of chunking the response, so that I don't have to handle the compression myself?

Answer 1

You could maybe play with the sendBufferSize to get a value big enough to contain your response in one chunk.

Then chunked content is part of the HTTP/1.1 protocol, you could force an HTTP/1.0 response (so not chunked: “A server MUST NOT send transfer-codings to an HTTP/1.0 client.”) by setting the force-response-1.0 in your apache configuration. But PHP breaks this settings, it's a long-known-bug of PHP, there's a workaround.

We could try to modify the request on the client side with an header preventing the chunked content, but w3c says: "All HTTP/1.1 applications MUST be able to receive and decode the "chunked" transfer-coding", so I don't think there's any header like 'Accept' and such which can prevent the server from chunking content. You could however try to set your request in HTTP/1.0, it's not really an header of the request, it's the first line, should be possible with jQuery, certainly.

Last thing, HTTP/1.0 lacks one big thing, the 'host' headers is not mandatory, verify your requests in HTTP/1.0 are still using the 'host' header if you work with name based virtualhosts.

edit: by using the technique cited in the workaround you can see that you could tweak Apache env in the PHP code. This can be used to force the 1.0 mode only for your special gzipped content, and you should use it to prevent having you complete application in HTTP/1.0 (or use the request mode to set the HTTP/1.0 for you gzip requests).