Apache Log4j is a Java-based logging utility. It was originally written by Ceki Gülcü and is part of the Apache Logging Services project of the Apache Software Foundation. Log4j is one of several Java logging frameworks.
Apache Log4j 2 is an upgrade to Log4j that provides significant improvements over its predecessor, Log4j 1.x, and provides many of the improvements available in Logback while fixing some inherent problems in Logback’s architecture.The main differences from Log4j 1 are:
- Improved reliability. Messages are not lost while reconfiguring the framework like in Log4j 1 or Logback
- Extensibility: Log4j 2 supports a plugin system to let users define and configure custom components
- Simplified configuration syntax
- Support for xml, json, yaml and properties configurations
- Improved filters
- Property lookup support for values defined in the configuration file, system properties, environment variables, the ThreadContext Map, and data present in the event
- Support for multiple APIs: Log4j 2 can be used with applications using the Log4j 2, Log4j 1.2, SLF4J, Commons Logging and java.util.logging (JUL) APIs.
- Custom log levels
- Java 8-style lambda support for "lazy logging"
- Support for user-defined Message objects
- "Garbage-free or low garbage" in common configurations
- Improved speed
Apache Log4j has been used in the oGaTe and IIX Gateway (Insurance oGaTe).