Invoke custom app function from support tool

Is it possible to invoke/trigger/execute a function/method defined inside the custom app, from the support tool by using triggers/webhook.

For example: I have a function fnGreeting() this function is defined in the custom app, the function will take a paramenter (sName) and will return back a welcome message "Hello to Ops Team Mr. {{sName}}. 

So the query is, is it possible to be able to call a function which is defined inside of a custom app, from the host Zendesk product (support) via Trigger/Webhook.