On Sat, 19 Jul 2003, Slava Bizyayev wrote:
Here is small correction to Web Content Compression FAQ.
What does HTTP/1.0 only support mean in this answer:
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Q: Are there any content compression solutions for vanilla Apache 1.3.X?
A: Yes, There are two compression modules written in C that are available
for vanilla Apache 1.3.X:
* mod_deflate
an Apache handler written in C by Igor Sysoev (Russia).
* mod_gzip
an Apache handler written in C. Original author: Kevin Kiley,
Remote Communications, Inc. (U.S.)
Both of these modules support HTTP/1.0 only.
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mod_deflate does not care about chunks at all - Apache does it.
If Apache's responses is HTTP/1.1 then Apache send it in chunks
because mod_deflate always deletes "Content-Length" header.
mod_deflate compresses content using 8K buffer. When the buffer
is filled mod_deflate passes the compressed data to Apache.
If an upstream module calls ap_bflush() to flush a pending data
then mod_deflate asks zlib to flush a compressed stream and
then passes a partially filled buffer to Apache. Since flushing
a compressed stream descreases a compression ratio so mod_deflate has
"DeflateIgnoreFlush" to ignore the ap_bflush() calls of an upstream module.
It can be used for example with Chili!Soft ASP that calls ap_bflush()
after any output even after an output of several bytes.
So mod_deflate as well as "Apache::Dynagzip are the only handlers
to date that begins transmission of compressed data as soon as
the initial uncompressed pieces of data arrive from their source,
at a time when the source process may not even have completed
generating the full document it is sending. Transmission can therefore
be taking place concurrent with creation of later document content".
Igor Sysoev
http://sysoev.ru/en/
