fcs-->acs
    end
```

#### ServiceDiscovery

The other primary interface is the ServiceDiscovery. Similar to ConfigStore, this aggregates over a variety of resources. However, it does not provide generic resource access, and instead precomputes a variety of service-oriented internal resources, such as `model.Service` and `model.ServiceInstance`.

In our experience and testing, these types force us to represent data in inefficient ways because they are general purpose.
Ztunnel is not general purpose; it has an extremely tight goal.
We can exploit this to make a more efficient protocol, which is critical to achieve our resource footprint goals.