The VMware vSphere Web Services SDK can be an efficient way to manage the vSphere environment.
To learn more about the VMware vSphere API and supported SDK libraries, refer to the vSphere API and SDK Documentation.
For examples of good programming practices, see code samples from the VMware Communities sample code page (http://communities.vmware.com/community/vmtn/developer/codecentral).
To use the SDK to obtain cluster performance data by aggregating information from individual hosts, see the vCenter Cluster Performance Tool fling (https://labs.vmware.com/flings/vcenter-cluster-performance-tool).