is it possible to create a WEB API that gets DATA from outside APPIAN?

Question

I am trying to create a WEB API that gets data from outside Appian and is available to start a PM with that data, however it doesn't seem to be available to work because I am getting a 404 page

Selvakumar Kumarasamy · Answer

Hi sergiog0002 , 
 It is possible to create a POST web API in Appian to receive triggers from an external source and start a process model. Wgile creating a Web API, you will have the template to create a start process API.

Can you provide more details on how do you get the 404 error? Like where did you test the API & what's the authentication method used?