We are running a POC on using temporal.io for managing data syncs in our infrastructure between disparate services. We want to enable a service to call and start a workflow without using the tctl cli. Is there or will there be some kind of REST or gRPC API that can be used to mimic the capabilities of tctl?
Temporal service exposes gRPC API for all its operation. tctl and Web UI rely only on this interface for their operation. So you can absolutely call any exposed gRPC operation using any existing gRPC client.
But for starting workflows you can use the higher level APIs exposed by our SDKs.