Vault has its own API, which is completely separate from the Inventor API.
C# and VB.NET are the recommended languages.
Vault's API is strictly used for communicating with the Vault server. There
is no way to interact with the existing Vault plug-in to Inventor, and there
is no way to customize the Vault Explorer client.
You can find more information in the Vault SDK, which gets installed
automatically with the Vault Server (ADMS). Go to your server machine and
find the "Data Management Server" install directory. There you will find
the SDK directory, which contains documentation and sample code.
Another great resource is the Vault discussion group:
http://discussion.autodesk.com/forum.jspa?forumID=101&start=0
If you tell me a bit more about what you are trying to do, I can give you
some advice on how to proceed.
Doug Redmond
Software Engineer, Autodesk Inc.