When you run the session, the Integration Service looks for the shared library or DLL in the runtime location you specify in the Custom transformation.
To run a session in a workflow:
In the Workflow Manager, create a workflow.
Create a session for this mapping in the workflow.
Copy the shared library or DLL to the runtime location directory.
Run the workflow containing the session.
When the Integration Service loads a Custom transformation bound to a procedure, it loads the DLL or shared library and calls the procedure you define.