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-rw-r--r--lib/README.http248
1 files changed, 30 insertions, 18 deletions
diff --git a/lib/README.http2 b/lib/README.http2
index f6d9cb9a8..e9084233b 100644
--- a/lib/README.http2
+++ b/lib/README.http2
@@ -1,6 +1,6 @@
HTTP2 with libcurl
- Spec: http://tools.ietf.org/html/draft-ietf-httpbis-http2
+ Spec: http://www.rfc-editor.org/rfc/rfc7540.txt
Document explaining it: http://daniel.haxx.se/http2/
@@ -15,9 +15,7 @@ HTTP2 with libcurl
than HTTP/1.1 (which we implement on our own) and that nghttp2 is an already
existing and well functional library.
- Right now, nghttp2 implements http2 draft-14
-
- We require at least version 0.6.0
+ We require at least version 1.0.0.
Over an http:// URL
@@ -52,16 +50,25 @@ SSL libs
GnuTLS: ALPN
PolarSSL: ALPN
-HTTP Alternative Services
+Multiplexing
- 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
+ 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
@@ -72,13 +79,18 @@ curl tool
curl offers the --http2 command line option to enable use of http2
-TODO:
+HTTP Alternative Services
- - Implement multiplexing
+ 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
- - 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
- re-use existing pipelining logic?
+TODO:
- Provide API to set priorities / dependencies of individual streams