An adapter to use SLF4J as service provider and runtime log engine for the ELF4J (Easy Logging Facade for Java) API

As an application developer using the ELF4J API, I want to have the option of selecting SLF4J as my log engine, at application deploy time without code change or re-compile.

• Java 8+

If you are using the ELF4J API for logging, and wish to select or change to use SLF4J as the run-time implementation, then simply pack this service provider in the classpath when the application deploys. No code change needed. At compile time, the client code is unaware of this run-time logging service provider. With the ELF4J facade, opting for SLF4J as the logging implementation is a deployment-time decision.

The usual SLF4J configuration applies.

With Maven, in addition to use compile-scope on the ELF4J API dependency, an end-user application would use runtime-scope for this provider as a dependency:

<dependency>
    <groupId>io.github.elf4j</groupId>
    <artifactId>elf4j</artifactId>
    <scope>compile</scope>
</dependency>

<dependency>
    <groupId>io.github.elf4j</groupId>
    <artifactId>elf4j-slf4j</artifactId>
    <scope>runtime</scope>
</dependency>

Note: Only one logging provider such as this should be in effect at run-time. If multiple providers end up in the final build of an application, somehow, then the elf4j.service.provider.fqcn system property will have to be used to select the desired provider.

java -Delf4j.service.provider.fqcn="elf4j.slf4j.Slf4jLoggerFactory" -jar MyApplication.jar