Endpoint Apps and Cloud to Cloud devices that run on AWS Lamda will able to utilize any language supported by AWS.
- Node
- Java
- Python
- C#
- Go
Groovy apps would need to be ported to a supported language for AWS-L, but the code could be hosted using a webhook smartapp on an endpoint server that supports the groovy language.
For an officially approved SmartApp that gets listed in our catalog, it would be up to the SmartApp provider to cover hosting costs. There could be a scenario where published Lamda apps are running in the SmartThings AWS instance but we have not resolved that aspect of the app approval life cycle yet.
There are existing examples of how “self-published” AWS app could work today and there is a free developer tier on AWS
See Echosistant and Ask Alexa
As an end user there should be no apparent difference in the way a SmartApp behaves once installed. The installation, configuration, and update cycles all look very similar to the old style apps you are used to with a quite a few new enhancements like being able to subscribe to all devices of a capability or having the select all feature that was previously only available to internal apps.
The new APIS allow for much more robust access to the platform to do things like rename/create devices and locations.
From a developer’s perspective this will open up a completely new category of SmartApps and integrations.
I am sure @tgauchat already has a lot of ideas about things Actiontiles could do with the new API.