src/sys/examples/topology/meta/echo_realm.cml

// Example realm that provisions an Echo client and service and eagerly runs the client.
{
    // Route Echo service from server to client.
    "offer": [
        {
            "service": "/svc/fidl.examples.topology.echo.Echo",
            "from": "#echo_server",
            "to": [
                {
                    "dest": "#echo_client",
                },
            ],
        },
    ],
    // Two children: a server and client. "echo_client" has "eager" startup so it
    // will be started along with the realm.
    "children": [
        {
            "name": "echo_server",
            "uri": "fuchsia-pkg://fuchsia.com/topology_example#meta/echo_server.cm",
        },
        {
            "name": "echo_client",
            "uri": "fuchsia-pkg://fuchsia.com/topology_example#meta/echo_client.cm",
            "startup": "eager",
        },
    ],
}