First things first: for most people with any kind of complicated set up, smartthings is a fairly high maintenance solution. Because it’s a cloud-based platform, the company can And does push out updates which you can neither refuse nor delay. They also make quite a few unannounced updates.
So you can have everything working great when you go to bed Sunday night, get up on Monday morning, and things just aren’t working anymore. Just diagnosing those can take quite a bit of time, as you can see from forum discussions. It can be a very powerful system, but it’s definitely not “set and forget.”
Second, because smartthings is a cloud-based system, there’s not a lot you can do by communicating directly to the hub. You have to go through the cloud. (All custom code runs in the cloud.) So once you do that, it’s often easiest to use one of the existing third-party integrations, in particular IFTTT, which I think is what most people who are not using webcore use for calendars, for example.
Which brings us to Webcore. this is essentially a scripting language for smartthings. Very powerful, very popular for community members who have a strong technical background. They even have their own forum. It has its own webhooks, which can be useful. It doesn’t remove any of the unreliability issues from SmartThings, but it can save you a lot of time if you are creating complex rules.
So read the short FAQ and then go over and talk to those folks in their forum and they should have a lot of ideas for you. 
( The topic title is a clickable link.)