The vCentre server is the management layer for managing the ESXi hosts. View integrates into the vCentre server to allow it to power on & off desktops. View composer talks to vCentre for any provisioning tasks that need to be ran e.g. Creating or deleting desktops and refreshing desktops at log off.
The vCentre server should be a dedicated vCentre server purely for the VDI Desktop environment and separate from any existing server environment.