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README.http2: refreshed and added TODO items

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Daniel Stenberg 2015-03-25 12:13:16 +01:00
parent 7b223a3a21
commit eb2a6180fb
1 changed files with 24 additions and 14 deletions
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lib/README.http2
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@ -1,8 +1,9 @@
HTTP2 with libcurl HTTP2 with libcurl
Spec: http://tools.ietf.org/html/draft-ietf-httpbis-http2 Spec: http://tools.ietf.org/html/draft-ietf-httpbis-http2
Document explaining it: http://daniel.haxx.se/http2/
Build prerequisites Build prerequisites
- nghttp2 - nghttp2
- OpenSSL, NSS, GnutTLS or PolarSSL with a new enough version - OpenSSL, NSS, GnutTLS or PolarSSL with a new enough version
@ -10,8 +11,8 @@ HTTP2 with libcurl
nghttp2 (https://github.com/tatsuhiro-t/nghttp2) nghttp2 (https://github.com/tatsuhiro-t/nghttp2)
libcurl uses this 3rd party library for the low level protocol handling libcurl uses this 3rd party library for the low level protocol handling
parts. The reason for this is that HTTP2 is much more complex at that layer parts. The reason for this is that HTTP/2 is much more complex at that layer
than HTTP1.1 (which we implement on our own) and that nghttp2 is an already than HTTP/1.1 (which we implement on our own) and that nghttp2 is an already
existing and well functional library. existing and well functional library.
Right now, nghttp2 implements http2 draft-14 Right now, nghttp2 implements http2 draft-14
@ -20,9 +21,9 @@ HTTP2 with libcurl
Over an http:// URL Over an http:// URL
If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2, libcurl will include If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2_0, libcurl will
an upgrade header in the initial request to the host to allow upgrading to include an upgrade header in the initial request to the host to allow
http2. upgrading to http2.
Possibly we can later introduce an option that will cause libcurl to fail if Possibly we can later introduce an option that will cause libcurl to fail if
not possible to upgrade. Possibly we introduce an option that makes libcurl not possible to upgrade. Possibly we introduce an option that makes libcurl
@ -30,10 +31,10 @@ HTTP2 with libcurl
Over an https:// URL Over an https:// URL
If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2, libcurl will use ALPN If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2_0, libcurl will use
(or NPN) to negotiate which protocol to continue with. Possibly introduce an ALPN (or NPN) to negotiate which protocol to continue with. Possibly
option that will cause libcurl to fail if not possible to use http2. introduce an option that will cause libcurl to fail if not possible to use
Consider options to explicitly disable ALPN and/or NPN. http2. Consider options to explicitly disable ALPN and/or NPN.
ALPN is the TLS extension that http2 is expected to use. The NPN extension ALPN is the TLS extension that http2 is expected to use. The NPN extension
is for a similar purpose, was made prior to ALPN and is used for SPDY so is for a similar purpose, was made prior to ALPN and is used for SPDY so
@ -51,15 +52,16 @@ SSL libs
GnuTLS: ALPN GnuTLS: ALPN
PolarSSL: ALPN PolarSSL: ALPN
Alt-Svc HTTP Alternative Services
Alt-Svc is a suggested new header with a corresponding frame (ALTSVC) in Alt-Svc is a suggested extension with a corresponding frame (ALTSVC) in
http2 that tells the client about an alternative "route" to the same content http2 that tells the client about an alternative "route" to the same content
for the same origin server that you get the response from. A browser or for the same origin server that you get the response from. A browser or
long-living client can use that hint to create a new connection long-living client can use that hint to create a new connection
asynchronously. For libcurl, we may introduce a way to bring such clues to asynchronously. For libcurl, we may introduce a way to bring such clues to
the applicaton and/or let a subsequent request use the alternate route the applicaton and/or let a subsequent request use the alternate route
automatically. automatically. Spec:
http://tools.ietf.org/html/draft-ietf-httpbis-alt-svc-05
Applications Applications
@ -70,8 +72,16 @@ curl tool
curl offers the --http2 command line option to enable use of http2 curl offers the --http2 command line option to enable use of http2
To consider: TODO:
- Implement multiplexing
- How to tell libcurl when using the multi interface that all or some of the - How to tell libcurl when using the multi interface that all or some of the
handles are allowed to re-use the same physical connection. Can we just handles are allowed to re-use the same physical connection. Can we just
re-use existing pipelining logic? re-use existing pipelining logic?
- Provide API to set priorities / dependencies of individual streams
- Implement "prior-knowledge" HTTP/2 connecitons over clear text so that
curl can connect with HTTP/2 at once without 1.1+Upgrade.