The user interface layer consists of an Adobe Flex application that is displayed in a Web browser. The Flex application contains all of the user interface elements with which you interact, such as menus, navigation elements, data portlets, and commands. You can navigate through the various Flex elements in the user interface layer to view data on vSphere objects, send commands, and make changes to the vSphere environment.

The exact configuration of the elements in the user interface layer depends on the unique properties of the vSphere environment and other factors such as the level of privileges each user has.

The service layer is a collection of Java services that run in a framework on the vSphere Web Client application server, called the Virgo server. The Java services communicate with VMware vCenter Server^® and other parts of the vSphere environment, as well as other remote data sources. The Java services gather monitoring data on the virtual infrastructure, which is in turn displayed by the Flex user interface layer. When you perform an action from the Flex user interface, such as a management or administration command, the Java services perform that command on the virtual infrastructure.

The vSphere Web Client application server contains a Spring framework that manages the communication between the user interface layer and the service layer.