You can still do this, but you have to do it in a completely different way.
As @fido mentioned, there is now a category of edge drivers that the community is calling “edge services” that allow you to reach server devices on your own LAN so you can use all kinds of integrations, and even use some we didn’t have before (like reaching an MQTT broker locally). But many will require running a 24/7 server device on your own Network, like a raspberry pi or a laptop. So not for everyone, but quite a few people are using these successfully.
To find the existing ones, see the “edge services“ list in the quick browse lists in the community-created wiki.
https://thingsthataresmart.wiki/index.php?title=Quick_Browse_Lists_for_Edge_Drivers
As far as more complex rules, there are several options for those depending on exactly what you’re trying to do. As noted in the first post of this thread, start with the following topic, and you’ll see discussion of the webcore alternatives:
Replace Groovy with Automations—what’s your plan?
If there’s a specific piston that you are trying to re-create in the new architecture, you can start a thread in the following section of the forum and hopefully someone will be able to help you:
You may still decide you’d rather go to a different platform— different things will work for different people. But there are probably more alternatives in the new smartthings architecture Than it looks like at first glance. After all, Webcore itself was an unofficial community project, and not mentioned anywhere in the smartthings app. So some research was required to find that one as well. 