Hi, may I know that how to use before/ after script to call external microservice or API, any sample?
Hi @kentlam 
First of all, Welcome to our community!! 
This scripting feature is not released to the public yet. FETIAS team will keep it posted once it is released.
Meanwhile, you may try FETIAS-Zapier integration which connect FETIAS to hundreds of other apps with Zapier.
Best Regards 