Previously stream ID was assigned just before HEADERS or PUSH_PROMISE
was serialized and nghttp2_submit_{request, headers, push_promise} did
not return stream ID. The application has to check assigned stream ID
using before_frame_send_callback. Now it is apparent that priority is
meant to DATA transfer only. Also application can reorder the
requests if it wants. Therefore we can assign stream ID in
nghttp2_submit_* functions and return stream ID from them. With this
change, now application does not have to check stream ID using
before_frame_send_callback and its code will be simplified.
We inherited gzip compression API from spdylay codebase. In spdylay,
the cost of having such API is almost free because spdylay requires
zlib for header compression. nghttp2 no longer uses gzip to header
compression. zlib dependency exists just for gzip compression API,
which is not an essential. So we decided to move gzip code to under
src and remove zlib dependency from libnghttp2 itself. As nghttp2
package, we depend on zlib to compile tools under src.
NGHTTP2_CLIENT_CONNECTION_PREFACE has the same content with
NGHTTP2_CLIENT_CONNECTION_HEADER, which is now obsoleted by
NGHTTP2_CLIENT_CONNECTION_PREFACE.
Tatsuhiro Tsujikawa
MATSUMOTO Ryosuke