The vSphere Web Client SDK provides a custom Model-View-Controller framework, also called Frinje framework. Understanding how the Frinje framework implements the MVC pattern is essential to developing data view extensions. The graphic elements of the View component of the MVC framework are implemented in MXML classes and the logic elements of the View component are implemented in ActionScript classes.

The vSphere Client and the vSphere Web Client application servers provide the Virgo server that consists of a collection of Java services. These Java services communicate with vCenter Server, ESXi hosts, and other data sources. Basic understanding in Java development is required.

You can extend the vSphere Client if you have a good understanding in Web application development by using JavaScript and HTML. You can use any user interface technology to create views for the vSphere Client UI layer. The samples provided within the SDK use the jQuery library.