Thank you for your interesting.
Our client have been done implemented properly with Marketing Cloud and Sales Cloud Core. also, they want to know how to send survey link provided by Survey Monkey within SMS Message through Custom Activity in Journey Builder.
But, They had a one thing that problem when to use Custom activity. The problem is Our client cannot use standard function. because they want to send a message through domestic numbers. ( In Korea, when sending a message using a mobile studio, it will be send by International number.) For this reason, Only the event entry source must be used.
in my opinion, After create a query activity that stores closed cases in a specific Data Extension, and then, automate Query Activity on an hourly basis in automation studio. I think that it should be stored data such as Contact ID, Contact Name, Case Id, ETC. it's very simply. and using Journey Builder, send message with personalized string to customer who case has been closed. it will be included what that the survey monkey link with personalized string from query activity automation.
I wonder if the above example is suitable for this circumstance. If not, Please Let me know how to use Survey Monkey in an integrated environment.
Thank you for your answer my question, and I hope you have a great day!