The URL pattern is as follows:
http[s]://IVYHOSTNAME[:PORT]/ivy/api/APPLICATIONNAME `http[s]://IVYHOSTNAME[:PORT]/ivy/api/APPLICATIONNAME `
e.g. http://ivymobile.work:8080/ivy/api/MobileShowCase
Hostname and Port should of course reference your front-end webserver (IIS in your case).
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If you are not sure whether the necessary URL is exposed by the front-end webserver at all you can open the engine/info resource with a browser: it should ask for a UserName/Password that is known in the ivy-app that you refer:
http[s]://IVYHOSTNAME[:PORT]/ivy/api/APPLICATIONNAME/engine/info`http[s]://IVYHOSTNAME[:PORT]/ivy/api/APPLICATIONNAME/engine/info`
e.g. http://ivymobile.work:8080/ivy/api/MobileShowCase/engine/info
