src/site/antora/modules/ROOT/pages/manual/eventlogging.adoc

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= Event Logger

link:../javadoc/log4j-api/org/apache/logging/log4j/EventLogger.html[`EventLogger`] is a convenience to log xref:manual/messages.adoc#StructuredDataMessage[`StructuredDataMessage`]s, which format their content in a way compliant with https://datatracker.ietf.org/doc/html/rfc5424#section-6[the Syslog message format described in RFC 5424].
Historically, `EventLogger` was added to help users migrate from SLF4J `EventLogger`, which was removed in https://www.slf4j.org/news.html#1.7.26[SLF4J version `1.7.26`].

[WARNING]
====
*Event Logger is deprecated for removal!*
We advise users to switch to plain `Logger` instead.
Refer to xref:manual/api.adoc[] on how to use `Logger`.
====

Compared to using link:../javadoc/log4j-api/org/apache/logging/log4j/Logger.html[a plain `Logger`], `EventLogger`

* attaches an `EVENT` xref:manual/markers.adoc[marker], and
* sets the xref:manual/customloglevels.adoc[level] to `OFF`, unless one is explicitly provided.

That is, following `EventLogger` usages:

[source,java]
----
EventLogger.logEvent(new StructuredDataMessage(...));
EventLogger.logEvent(new StructuredDataMessage(...), Level.INFO);
----

are equivalent to the following plain `Logger` usages:

[source,java]
----
private static final Marker EVENT_MARKER = MarkerManager.getMarker("EVENT");
private static final Logger LOGGER = LogManager.getLogger();

LOGGER.log(Level.OFF, EVENT_MARKER, new StructuredDataMessage(...));
LOGGER.info(EVENT_MARKER, new StructuredDataMessage(...));
----