Most of JMP can be driven through OLE automation. Please see the Automation Reference.pdf in JMP/13/Documentation for details about automating JMP. This document introduces how to automate JMP through Visual Basic and using Visual C++ with MFC. It also contains details for the methods and properties that JMP exposes to automation clients like Visual Basic and Visual C++.
The JMP Samples/Automation folder contains several sample Visual Basic .Net, and Visual C# .Net files.