I think your starting point is here:
SDKs: vSphere SDK, vCenter SDK, vCloud SDK - VMware Developer Center
We have PHP, .NET, and Java SDKs already. Or you can use a standard REST API client to communicate with vCloud Director.
There is a dedicated forum for developers. e.g.: https://developercenter.vmware.com/forums?id=3221
If you want a higher level of assistance, support can be SDK support can be purchased from VMware.