I wanted to share this blog post from Jack Vanlightly ( https://twitter.com/vanlightly) because it's an excellent deep-dive into how Pulsar works, drilling down to all the levels of abstraction.
Very nice read! https://jack-vanlightly.com/blog/2018/10/2/understanding-how-apache-pulsar-works -- Matteo Merli <mme...@apache.org>