As mentioned earlier, WildFly handles traffic on different protocols through listeners. The only one that is enabled out of the box is the HTTP listener. If support is needed for AJP and HTTPS, the corresponding listeners will need to be configured and enabled. In earlier versions of the application server, there were quite a few settings that had to do with performance tuning on these protocol configurations (mainly thread pools settings). This is not the case in Undertow as thread handling is handled earlier in the stack by the I/O subsystem and using XNIO.

Two key components are configured by the Undertow subsystem. First, there is a XNIO worker pointed out by the worker attribute and named default by default. Secondly, there is a buffer pool pointed out by the buffer pool attribute. Even though clear by context, this is—like so many other things in in the default configuration of WildFly—also named default. We will now have a more detailed look into these components.