--- a/rust/src/sensor.rs	Wed Dec 21 21:40:32 2016 +0800
+++ b/rust/src/sensor.rs	Fri Dec 23 00:33:19 2016 +0800
@@ -14,29 +14,28 @@
     value: Option<f32>,
 }
 
-pub type Readings = Vec<Reading>;
-
 pub struct Sensor {
     current: f32,
+    suf: String,
 }
 
 impl Sensor {
-
-    fn step(&mut self) -> Readings {
+    fn step(&mut self) -> Vec<Reading> {
         let mut r = Vec::new();
         self.current = self.current + 0.1;
-        r.push(Reading { name: "aaa".to_string(), value: Some(self.current) });
+        r.push(Reading { name: "aaa".to_string() + &self.suf, value: Some(self.current) });
+        r.push(Reading { name: "b".to_string() + &self.suf, value: Some(self.current/3.0) });
         r
     }
 
-    fn new() -> Self {
-        Sensor { current: 22.0 }
+    fn new(suffix: String) -> Self {
+        Sensor { current: 22.0, suf: suffix }
     }
 
-    pub fn run(handle: &Handle) -> Box<Stream<Item=Readings, Error=io::Error>> {
-        let mut s = Sensor::new();
+    pub fn run(handle: &Handle, rate: u64, suffix: String) -> Box<Stream<Item=Vec<Reading>, Error=io::Error>> {
+        let mut s = Sensor::new(suffix);
 
-        let dur = Duration::from_millis(400);
+        let dur = Duration::from_millis(rate);
         Interval::new(dur, handle).unwrap().map(move |()| {
             s.step()
         }).boxed()