Recently in learning, netty use ChannelHandlerContext interface again many ways will not use, such as writeAndFlush fireChannelRead, fireChannelActive, what these three methods use please? If I am in a handler processes the data to be notified of the next handler channelRead method calls, you should use ChannelHandlerContext in which API? Or I will notify the next handler channelActive method calls, and which the API should be used?