It's one thing to have your workflow start off of events from other systems, like Safesforce, Box, Twilio, a Form or a Schedule. But if you have something custom that is built or being built for you, you can have that custom application instantiate a workflow in Nintex Workflow Cloud. In the video above, I talk about how I put together some C# code that uploads files to NWC and that starts an instance of a workflow.
There's no reason that this needs to be C#. You could use whatever programming language you want. Since an NWC Component Workflow has a REST endpoint, anything that has web access, can make a HTTP POST to it.
This opens up a variety of scenarios where you can instantiate workflows from systems you never even thought of.
Below, is an export of the workflow (workflow key) and a zip file of the source code. Hopefully this opens your mind to more possibilities.
Nintex Cloud Trial
Nintex Workflow Cloud - NWC External Start Workflow - 16dc177cd1e247659a105f7a87e585c8
Visual Studio Project C# - Download