appserver.io is an open source multithreaded application server for PHP. It has some advanced features and capabilites that enable you create powerful applications with PHP that tradtionally would of required Java or .Net.
Webserver Fully HTTP/1.1 compliant, component based webserver with FastCGI module
Rewrite Engine Webserver module for rewriting URLs and redirecting requests
Servlet Engine Container that loads applications and objects (= servlets) on application startup persistently into memory
Persistence Container Enables developers to hold objects in memory and bind them to specific sessions or use them globally
Message Queue Service with the ability to process message objects asynchronously
The best approach is to follow the detailed guide provided by the appserver.io documentation: