log4j example snippet:

    <appender name="ROLLINGFILE" class="com.holmbech.PositronAppender">
        <param name="File" value="log4j.txt"/>
        <param name="Append" value="true"/>
        <param name="MaxFileSize" value="5MB"/>
        <param name="MaxBackupIndex" value="5"/>
        <param name="MinimumLevelToAdd" value="Level.INFO"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d{ISO8601} %-5p %c{5} - %m%n"/>
        </layout>
    </appender>

AppenderAttachable version:
    <appender name="ROLLINGFILE" class="org.apache.log4j.RollingFileAppender">
        <param name="File" value="log4j.txt" />
        <param name="Append" value="true" />
        <param name="MaxFileSize" value="5MB" />
        <param name="MaxBackupIndex" value="5" />
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d{ISO8601} %-5p %c{5} - %m%n" />
        </layout>
    </appender>
            
    <appender name="POSITRONIC" class="com.holmbech.PluggablePositronAppender">
        <appender-ref "ROLLINGFILE" />
        <param name="MaximumLevelToStore" value="Level.WARN" />
        <param name="BufferSize" value="50" />
    </appender>

    <root>
        <level value="DEBUG" />
        <appender-ref ref="POSITRONIC" />
    </root>