Design Logging Framework

Difficulty: Easy Source: awesome-low-level-design

Requirements

  1. Log levels: DEBUG, INFO, WARNING, ERROR, FATAL
  2. Messages include timestamp, level, content
  3. Multiple output destinations: console, file, database
  4. Configurable log level and output
  5. Thread-safe concurrent logging
  6. Extensible for new levels and destinations

Class Diagram

Class Diagram

Classes, Interfaces and Enumerations

Class/Interface Description
LogLevel Enum for log levels: DEBUG, INFO, WARNING, ERROR, FATAL
LogMessage timestamp, level, message content
LogAppender Interface for output destinations
ConsoleAppender Concrete appender; writes log messages to console
FileAppender Concrete appender; writes log messages to file
DatabaseAppender Concrete appender; writes log messages to database
LoggerConfig Holds active log level and appender
Logger Singleton; core logging functionality

Design Patterns Used

Pattern Application
Singleton Logger has a single instance across the application
Strategy LogAppender interface allows swapping output destinations at runtime
Open/Closed Principle New appenders can be added without modifying existing code

Code Implementations

Language Source Code
Java View on GitHub
Python View on GitHub
C++ View on GitHub
C# View on GitHub
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