Resilience Engine

Overview

A Java-based execution framework designed to manage task resilience in unstable environments. It implements advanced Design Patterns to handle execution failures using modular strategies, protecting system resources from cascading failures through intelligent state management.

Key Patterns Applied

• Strategy Pattern: Decouples retry and circuit breaker logic from the execution engine
• State Pattern: Implements a three-state Circuit Breaker (Closed, Open, Half-Open) to manage system health
• Observer Pattern: Provides a decoupled monitoring layer to log failures without affecting business logic
• Command Pattern: Encapsulates operations into generic Task objects

Technical Features

• Generics: Full support for typed task returns using Java Generics
• Custom Exception Hierarchy: Specific resilience error handling via ResilienceException
• Resource Protection: Immediate request blocking when the system detects persistent external failures

Project Structure

resilience-engine/
├── src/
│   ├── core/
│   │   ├── Task interfaces
│   │   ├── Generic Executor
│   │   └── Custom exceptions
│   ├── strategies/
│   │   ├── FixedRetry
│   │   ├── ExponentialBackoff
│   │   └── CircuitBreaker
│   ├── monitoring/
│   │   ├── Observer interfaces
│   │   └── Logging implementations
│   └── tasks/
│       └── Concrete implementations (e.g., NetworkTask)
└── README.md

Requirements

• JDK 17 or higher

Execution

Compilation

javac -d bin src/**/*.java src/*.java

Running

java -cp bin Main

Academic Context

Course: Advanced Object-Oriented Programming (Programação Orientada a Objetos Avançada)
Department: Department of Computing (DC)
Institution: Federal University of São Carlos (UFSCar)

Design Patterns Reference

Strategy Pattern

Allows the selection of retry algorithms at runtime, enabling flexible failure handling strategies without modifying the core execution logic.

State Pattern

The Circuit Breaker transitions between three states:

• Closed: Normal operation, requests pass through
• Open: Failure threshold exceeded, requests are blocked
• Half-Open: Testing phase to check if the system has recovered

Observer Pattern

Monitoring components observe execution events without tight coupling to the execution engine, facilitating extensible logging and metrics collection.

Command Pattern

Tasks are encapsulated as first-class objects, enabling queuing, scheduling, and execution of operations in a uniform manner.

License

This project is developed for academic purposes at UFSCar.

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