5 Fault tolerance

This chapter covers Akka’s tools for making applications more resilient. The first section describes the let-it-crash principle, including supervision, monitoring, and actor lifecycle features. Of course, you’ll look at some examples that show how to apply these to typical failure scenarios.

5.1 What fault tolerance is (and what it isn’t)

5.1.1 Plain old objects and exceptions

5.1.2 Wrap it up and Let it crash

5.2 Actor lifecycle events. Signals

5.3 Supervision strategies and Signals

5.3.1 Uneventful resuming

5.3.2 Stopping and the poststop Signal

5.3.3 Restart and prerestart signal

5.4 Watching Signals from an actor

5.5 Back to the initial use case

5.5.1 Supervisor hierarchy initial desing

5.5.2 Supervision Hierarchy alternative design

5.5.3 Sketching the design

5.6 Summary