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From: Stefan Eissing <stefan.eissing@greenbytes.de>
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Subject: Protocols directive, NEW
Message-Id: <D22623B4-C425-4EEB-92A3-D2EE63A731B8@greenbytes.de>
Date: Fri, 24 Jul 2015 14:23:48 +0200
To: dev@httpd.apache.org
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In best programmers' tradition, I just made a large commit just before =
my vacation...In good Apache tradition, however, I ran all regression =
tests with it. So, hopefully this works for you as well, otherwise, =
please just revert the commit and curse my name.

CAVEAT: this commit changes mod_ssl and core_config structures. A "make =
clean" is recommended. As the core API was extended, you might also have =
to delete installed header files.

The new directive "Protocols" is implemented for server and vhosts. =
Example

  Protocols http/1.1 h2             #supports HTTP/1 and HTTP/2 (when =
over TLS) and prefers to talk HTTP/1.

  Protocols h2 spdy/3.1 http/1.1    #HTTP/2 is preferred over spdy with =
HTTP/1.1 coming last.

When no "Protocols" are specified, all protocols implemented in the =
server can be negotiated. Protocols from a base server are additive. The =
ALPN negotiated now calls the new core APIs which can be found in =
http_protocol.h (seemed the most suitable place).

Registration is done in three hooks. An implementation can be seen in =
h2_switch.c

Missing:
- Directive documentation (My excuse is that it will change after =
feedback+discussion anyway)
- Ordering directive - not sure if we need it. I will ask the browser =
implementors on the HTTP workshop on Monday what their requirements are

Discussion:
- Is the default for "Protocols" what we want?
- Is the additive nature of "Protocols" what we want?
- Is this the right abstraction? I tried to make it general enough that =
other mechanisms may use the same API and other protocols find it easy =
to register. Nevertheless, once cannot foresee the future and what =
requirements come up. My overall impression is that the code is smaller =
and cleaner now. mod_h2's pre-connection hook with registration became =
unnecessary.

Cheers,

  Stefan


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