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Diffstat (limited to 'lib')
| -rw-r--r-- | lib/README.http2 | 99 |
1 files changed, 0 insertions, 99 deletions
diff --git a/lib/README.http2 b/lib/README.http2 deleted file mode 100644 index e9084233b..000000000 --- a/lib/README.http2 +++ /dev/null @@ -1,99 +0,0 @@ -HTTP2 with libcurl - - Spec: http://www.rfc-editor.org/rfc/rfc7540.txt - - Document explaining it: http://daniel.haxx.se/http2/ - - Build prerequisites - - nghttp2 - - OpenSSL, NSS, GnutTLS or PolarSSL with a new enough version - - nghttp2 (https://github.com/tatsuhiro-t/nghttp2) - - libcurl uses this 3rd party library for the low level protocol handling - parts. The reason for this is that HTTP/2 is much more complex at that layer - than HTTP/1.1 (which we implement on our own) and that nghttp2 is an already - existing and well functional library. - - We require at least version 1.0.0. - - Over an http:// URL - - If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2_0, libcurl will - include an upgrade header in the initial request to the host to allow - upgrading to http2. - - 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 - use http2 at once over http:// - - Over an https:// URL - - If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2_0, libcurl will use - ALPN (or NPN) to negotiate which protocol to continue with. Possibly - introduce an option that will cause libcurl to fail if not possible to use - http2. Consider options to explicitly disable ALPN and/or NPN. - - 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 - early http2 servers are implemented using NPN before ALPN support is - widespread. - -SSL libs - - The challenge is the ALPN and NPN support and all our different SSL - backends. You may need a fairly updated SSL library version for it to - provide the necessary TLS features. Right now we support: - - OpenSSL: ALPN and NPN - NSS: ALPN and NPN - GnuTLS: ALPN - PolarSSL: ALPN - -Multiplexing - - Starting in 7.43.0, libcurl fully supports HTTP/2 multiplexing, which is the - term for doing multiple independent transfers over the same physical TCP - connection. - - To take advantage of multiplexing, you need to use the multi interface and - set CURLMOPT_PIPELINING to CURLPIPE_MULTIPLEX. With that bit set, libcurl - will attempt to re-use existing HTTP/2 connections and just add a new stream - over that when doing subsequent parallel requests. - - While libcurl sets up a connection to a HTTP server there is a period during - which it doesn't know if it can pipeline or do multiplexing and if you add - new transfers in that period, libcurl will default to start new connections - for those transfers. With the new option CURLOPT_PIPEWAIT (added in 7.43.0), - you can ask that a transfer should rather wait and see in case there's a - connection for the same host in progress that might end up being possible to - multiplex on. It favours keeping the number of connections low to the cost - of slightly longer time to first byte transfered. - -Applications - - We hide http2's binary nature and convert received http2 traffic to headers - in HTTP 1.1 style. This allows applications to work unmodified. - -curl tool - - curl offers the --http2 command line option to enable use of http2 - -HTTP Alternative Services - - 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 - 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 - 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 - automatically. Spec: - http://tools.ietf.org/html/draft-ietf-httpbis-alt-svc-05 - -TODO: - - - 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. - |