--- a/rust/src/sensor.rs	Wed Dec 21 08:16:13 2016 +0800
+++ b/rust/src/sensor.rs	Wed Dec 21 21:40:32 2016 +0800
@@ -2,39 +2,43 @@
 extern crate futures;
 
 use std::time::Duration;
-use std;
-use std::cell::RefCell;
+use std::io;
 
 use tokio_core::reactor::Interval;
-use tokio_core::reactor::Core;
 use tokio_core::reactor::Handle;
 use futures::Stream;
-use futures::Future;
 
-pub struct Readings {
-
+#[derive(Debug)]
+pub struct Reading {
+    name: String,
+    value: Option<f32>,
 }
 
+pub type Readings = Vec<Reading>;
+
 pub struct Sensor {
+    current: f32,
 }
 
 impl Sensor {
 
-    fn step(self) -> Readings {
-        return Readings {}
-    }
-
-    pub fn new() -> Sensor {
-        Sensor {}
+    fn step(&mut self) -> Readings {
+        let mut r = Vec::new();
+        self.current = self.current + 0.1;
+        r.push(Reading { name: "aaa".to_string(), value: Some(self.current) });
+        r
     }
 
-    pub fn run(handle: &Handle) -> Box<Future<Item=Readings, Error = std::io::Error>> {
-        let s = Sensor::new();
+    fn new() -> Self {
+        Sensor { current: 22.0 }
+    }
 
-        Interval::new(Duration::from_millis(400), handle).map(|()| {
-            println!("each one");
-     //       s.step()
-            Readings {}
+    pub fn run(handle: &Handle) -> Box<Stream<Item=Readings, Error=io::Error>> {
+        let mut s = Sensor::new();
+
+        let dur = Duration::from_millis(400);
+        Interval::new(dur, handle).unwrap().map(move |()| {
+            s.step()
         }).boxed()
     }
 }