As observed in my earlier articles, the Java EE PaaS portfolio is gaining in strength each day, with support from major players such as IBM, Oracle, VMWare, Redhat , Google and Amazon.
However unlike the Microsoft > .NET Framework > Azure PaaS equation where there is just one version of the framework from one vendor, the openness of Java EE led to several implementations of application server-specific implementations.
As Java EE standards define a core set of API, frame works and features as part of its implementation, an application server is the container that executes these instructions and provides a development and runtime platform for Java EE applications.