A quite common setup for Java EE application servers, where clients are use HTTP, is to have a native web server, such as Apache HTTPD, acting as a frontend server. This setup has the following potential benefits:
HTTPS termination: Handling the computations of HTTPS encryption and decryption takes a lot of CPU usage. A native stack (as in Apache HTTPD) or even designated hardware, is normally more optimized and faster than handling these computations in Java.
Tip
In this book, we use Apache HTTPD as an example, as it is very versatile and is the most common web server in the world. Several options, such as nginx and lighttpd, are however available and should be evaluated before deciding on which to use.
In most scenarios, it is allowed to terminate HTTPS in the frontend (that can execute on it's own hardware that is separate from the application server) and use unencrypted traffic within the infrastructure of the application server. Your IT security policies and business...