Room for improvement:
The introduction in the slide notes is somehow confused:
The vSphere Web Client uses the architecture shown. Accessed from a browser run on a machine of the user’s choosing, the vSphere Web Client is accessed from vCenter Server directly.Correct:
It's the vSphere Web Client that directly accesses, via the network, the vCenter Server:
The vSphere Web Client is a Web application installed on a machine with network access to your vCenter Server installation.Source:
VMware vSphere 5.5 Documentation Center.
And it's the vSphere Web Client that actually pulls data from the vCenter Server DB when users navigate through the various screens and views, not vice-versa. This is further explained in a later sentence within the same slide notes paragraph:
The application server runs a flex client that feeds the user interface data to the browser. This flex client pulls information from the Inventory Service on the vCenter Server system that provides data optimized for the Web UI to the flex client.