Call another workflow from a custom form element activity code?

I have a custom workflow form element built with the SDK. I would like to call another workflow from the custom form element code. I can get this to work if I am using the older html viewer by grabbing the local geocortex object and using that api, but how would I future proof this to run another new workflow by url in a new Web Viewer application? Is there a built in api I can use to call another workflow?

--Marc