Building a Durable Execution Engine with SQLite
2 days ago
- #Java
- #DurableExecution
- #SQLite
- Durable Execution (DE) engines ensure multi-step workflows persist and can resume from the last successful step after interruptions.
- DE engines prevent repeated execution of successful steps, ensuring correctness, efficiency, and determinism in workflows.
- Modern DE engines allow workflows to be defined in general-purpose programming languages like Python, TypeScript, or Java.
- Persistasaurus is a basic DE engine implemented in Java using SQLite for persistence, demonstrating modern Java capabilities.
- Flows in Persistasaurus are defined with @Flow and @Step annotations, with steps being the unit of persistence.
- The engine uses SQLite to log execution steps, their status, parameters, and results for resumption after failures.
- Delayed execution steps are implemented using Java's virtual threads, allowing flows to pause and resume after a delay.
- Human-in-the-loop steps are supported, where flows await external input before continuing, using scoped values for safety.
- SQLite is suitable for embedded scenarios like self-contained AI agents, while client/server databases fit high-concurrency systems.
- Centralized DE engines like Temporal and Restate manage state across services but introduce coupling and potential single points of failure.