Functional Requirements of a Logger

Log Messages with Severity Levels

The Logger must support various log levels such as:

• DEBUG
• INFO
• WARN
• ERROR
• FATAL

It should allow configuration to record only messages at or above a specific level.

Output to Multiple Destinations

The Logger should be capable of writing logs to:

• Console (standard output)
• Files (log files with defined paths)
• External services (optional, e.g., over network or monitoring tools)

Include Timestamps and Context

Each log entry must capture:

• Date and time of the event
• Log level
• Message content
• Optional metadata such as class name, thread, or user

Runtime Log Level Configuration

The system should allow changing the log level at runtime to increase or reduce verbosity as needed.

• Support for Structured or Formatted Logs
  Ability to define custom log formats, such as plain text, JSON, or XML, for better integration with other tools.

Non-Functional Requirements of a Logger

Performance
Logging should not degrade application performance. For high-frequency logging, mechanisms like buffered or asynchronous logging should be used.

Thread Safety
The Logger must handle concurrent logging from multiple threads without conflicts or data corruption.

Reliability
Logging should not crash the application. If an error occurs during logging (e.g., file not found), it should fail silently or log the failure internally.

Extensibility
The Logger should be designed to easily support additional log levels, new formats, or output destinations in the future.

Maintainability
Code should follow clean design principles and be modular, making it easy to update or replace specific components like file handlers or formatters.

Portability
The logger implementation should work across different environments and platforms without requiring major changes.