NOTE
Netty Source: Pipeline Initialization
How every Channel owns a pipeline of handler contexts and how initial handlers are installed.
This is a historical learning note and may contain outdated or incomplete understanding.
Each channel owns a ChannelPipeline, conceptually a doubly linked chain of handler contexts with head/tail infrastructure nodes.
Bootstrap/channel initialization adds codecs and application handlers. Each context knows its handler, executor/event-loop association, and neighbors used for event propagation.
Pipeline structure may be changed dynamically, but handler lifecycle/thread-safety requirements must be respected. The linked-context implementation is an internal technique; the API contract is ordered inbound/outbound event processing.