Yes, currently all activities must conform to the WASI 0.2 standard. This is the simplest for deployment, as you only need the obelisk executable, toml config file. The webhooks, workflows and activities pulled from a OCI registry on startup.
To support native code I plan to add external activities as well, with an interface similar to what Netflix Conductor uses for its workers.
> Finally, do you see the component's interface as the right layer for capturing IO?
An activity must encapsulate something much higher level than a single IO operation. So something like "Configure BGP on a router", "Start a VM" etc. It needs to be able to handle retries and thus be idempotent.
Regarding performance, a workflow execution can call 500-700 child executions serially, or around 1400 child executions concurrently per second.
