diff --git a/examples/jack-sine/src/main.rs b/examples/jack-sine/src/main.rs
index cee0003..379d246 100644
--- a/examples/jack-sine/src/main.rs
+++ b/examples/jack-sine/src/main.rs
@@ -2,6 +2,7 @@
 //! input.
 
 use crossbeam_channel::bounded;
+use jack::{PortFlags, PortSpec};
 use std::io;
 use std::str::FromStr;
 
@@ -9,6 +10,11 @@ fn main() {
     // 1. open a client
     let (client, _status) =
         jack::Client::new("rust_jack_sine", jack::ClientOptions::default()).unwrap();
+    let ports = client.ports(None, Some(jack::AudioIn::default().jack_port_type()), PortFlags::empty());
+    println!("All JACK ports:");
+    for port in ports {
+        println!("{}", port);
+    }
 
     // 2. register port
     let out_port = client
diff --git a/lib/proto/audio_backend.proto b/lib/proto/audio_backend.proto
index e63b401..ddeb773 100644
--- a/lib/proto/audio_backend.proto
+++ b/lib/proto/audio_backend.proto
@@ -27,6 +27,8 @@ message DesiredAudioBacked {
 
 message AudioBackendDescription {
   CoreAudioAvailableOptions core_audio_description = 1;
+  repeated string input_devices = 2;
+  repeated string output_devices = 3;
 }
 
 message CoreAudioAvailableOptions {