Actions:

GetFields(PDFBinaryIn) -> Which will fetch all form fields of the PDF with their current value (KeyValueList)
FillFields(PDFBinaryIn, KeyValueList) -> Which will fill in the form fields based on the list provided,will return the binary of the result PDF.

Exceptions:

BadPassword -> If there is an "user" password set on the document (owner password will be ignored) it will be unable to read the PDF and thus return this exception.