An Http2Connection. Encapsulates the socket(channel) and any SSLEngine used over it. Contains an HttpConnection which hides the SocketChannel SSL stuff. Http2Connections belong to a Http2ClientImpl, (one of) which belongs to a HttpClientImpl. Creation cases: 1) upgraded HTTP/1.1 plain tcp connection 2) prior knowledge directly created plain tcp connection 3) directly created HTTP/2 SSL connection which uses ALPN. Sending is done by writing directly to underlying HttpConnection object which is operating in async mode. No flow control applies on output at this level and all writes are just executed as puts to an output Q belonging to HttpConnection Flow control is implemented by HTTP/2 protocol itself. Hpack header compression and outgoing stream creation is also done here, because these operations must be synchronized at the socket level. Stream objects send frames simply by placing them on the connection's output Queue. sendFrame() is called from a higher level (Stream) thread. asyncReceive(ByteBuffer) is always called from the selector thread. It assembles incoming Http2Frames, and directs them to the appropriate Stream.incoming() or handles them directly itself. This thread performs hpack decompression and incoming stream creation (Server push). Incoming frames destined for a stream are provided by calling Stream.incoming().