README.http2: refreshed and added TODO items

lib/README.http2

@@ -1,17 +1,18 @@
-
 HTTP2 with libcurl
 
  Spec: http://tools.ietf.org/html/draft-ietf-httpbis-http2
 
+ 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 HTTP2 is much more complex at that layer
-  than HTTP1.1 (which we implement on our own) and that nghttp2 is an already
+  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.
 
   Right now, nghttp2 implements http2 draft-14
@@ -20,20 +21,20 @@ HTTP2 with libcurl
 
  Over an http:// URL
 
-  If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2, libcurl will include
-  an upgrade header in the initial request to the host to allow upgrading to
-  http2.
+  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, 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.
+  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
@@ -51,15 +52,16 @@ SSL libs
     GnuTLS:   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
   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.
+  automatically. Spec:
+  http://tools.ietf.org/html/draft-ietf-httpbis-alt-svc-05
 
 Applications
 
@@ -70,8 +72,16 @@ curl tool
 
   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
     handles are allowed to re-use the same physical connection. Can we just
     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.
+