Chapter 4 - Reliable Request-Reply Patterns # Chapter 3 - Advanced Request-Reply Patterns covered advanced uses of ZeroMQ’s request-reply pattern with working examples. This chapter looks at the general question of reliability and builds a set of reliable messaging patterns on top of ZeroMQ’s core request-reply pattern. In this chapter, we focus heavily on user-space request-reply patterns, reusable models that help you design your own ZeroMQ architectures: The Lazy Pirate pattern: reliable request-reply from the client side The Simple Pirate pattern: reliable request-reply using load balancing The Paranoid Pirate pattern: reliable request-reply with heartbeating The Majordomo pattern: service-oriented reliable queuing The Titanic pattern: disk-based/disconnected reliable queuing The Binary Star pattern: primary-backup server failover The Freelance pattern: brokerless reliable request-reply What is “Reliability”?