What is "classpath mode", as seen in WildFly documentation?

Question

The WildFly documentation for version 16 says

WildFly 16 also is heavily tested and runs well on Java 8. We plan to continue to support Java 8 at least through WildFly 18.

Please note that WildFly runs on Java 11 and 12 in classpath mode.

What does this mean?

Answer 1

'Classpath mode' is just how Java has always previously worked prior to the introduction of the Java 9 module system.

It is used in juxtaposition to 'module mode'.

Classpath mode

At compile-time, a Java compiler does not directly compile a module declaration.

Observability (JLS 7.3) is determined solely by the host system, and consistently for all compilation units. The host system typically considers classes on the classpath and/or sourcepath as the entire observable universe (plus classes named on the command line).

This is how Java works today.

See Project Jigsaw: JDK Modularization Tips