The Three Durable Function Forms

Following my posts on determinism and durable function trees, this installment advances this blog post series “The Theory of Durable Execution”.Durable execution engines (DEEs) talk about “workflows”, “activities”, “virtual objects”, “handlers”, and “functions”, but they’re often describing the same underlying execution patterns. This post proposes a model that extends the generic durable function into three forms: stateless functions, sessions, and actors. I’ll cover this in three parts:The behavior-state continuumThe three durable function forms and associated propertiesMapping the DE frameworks to these formsThe Behavior-State ContinuumWe can think about the mix of computation and data in ordinary programming along a simple behavior–state continuum: Fig 1. (behavior only) -> (behavior with state) -> (state with behavior) -> (state-only) These points correspond to familiar constructs:Pure behavior: Like a stateless function in Functional Programming. A piece of logic that runs to…