I want to integrate wacom digital signature with tablet, Just like ria or western Union. I see that there are different way to accomplish this. With sdk or sign pro pdf api . Can someone please explain the difference? With api based solution, after signed the document, signed pdf status will sent by push notifications so that we can download the signed pdf ? Sdk based solution will be faster ? Also sdk based solution doesn’t need to use any external software like sign pro pdf that i have seen on ria . I am confused. Please someone help me to decide. Thanks in advance.
Nb. For commercial use do i need to buy sdk license?

I have tried an api based solution from another company, they use external software to open pdf, and also sent push notifications for signed status, which can be time delay and network or server issue specially for a money transfer company.