diff --git a/bindings/codemp_client.cpython-38-darwin.so.REMOVED.git-id b/bindings/codemp_client.cpython-38-darwin.so.REMOVED.git-id
index 0127aff..3df941f 100644
--- a/bindings/codemp_client.cpython-38-darwin.so.REMOVED.git-id
+++ b/bindings/codemp_client.cpython-38-darwin.so.REMOVED.git-id
@@ -1 +1 @@
-8d18661818436ebf65d16f9447601b123aef410e
\ No newline at end of file
+80ba7b16f0b0647e2f1d8520f3a90c51000bbd2c
\ No newline at end of file
diff --git a/build.sh b/build.sh
index 2395b00..e75ee18 100755
--- a/build.sh
+++ b/build.sh
@@ -14,7 +14,9 @@ PYO3_PYTHON="$(pyenv which python)"
 PYTHON_SYS_EXECUTABLE="$PYO3_PYTHON"
 CARGO_FEATURES="pyo3/extension-module"
 
+echo "Building with python: $PYO3_PYTHON"
 env PYO3_PYTHON="${PYO3_PYTHON}" PYTHON_SYS_EXECUTABLE="$PYO3_PYTHON" cargo build --features "$CARGO_FEATURES"
+echo "Copying into: $TARGET_DIR/$FULL_TARGET"
 
 [[ -f "$TARGET_DIR/$FUll_TARGET" ]] && echo "$FILE exists."
 ditto "$BUILD_DIR/${FILENAME}.dylib" "$TARGET_DIR/$FULL_TARGET"
diff --git a/src/lib.rs b/src/lib.rs
index 240fa27..07d19c8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -38,9 +38,7 @@ impl From<PyCodempError> for PyErr {
 #[pyfunction]
 fn codemp_init<'a>(py: Python<'a>) -> PyResult<Py<PyClientHandle>> {
     let py_instance: PyClientHandle = CodempInstance::default().into();
-    Python::with_gil(|py| {
-        Ok(Py::new(py, py_instance)?)
-    })
+    Ok(Py::new(py, py_instance)?)
 }
 
 #[pyclass]
@@ -79,12 +77,13 @@ impl PyClientHandle {
         let rc = self.0.clone();
 
         pyo3_asyncio::tokio::future_into_py(py, async move {
-            let buffctrl = rc.attach(path.as_str())
+            let buffctrl: PyBufferController = rc.attach(path.as_str())
                 .await
-                .map_err(PyCodempError::from)?;
+                .map_err(PyCodempError::from)?
+                .into();
 
             Python::with_gil(|py| {
-                Ok(Py::new(py, PyBufferController(buffctrl))?)
+                Ok(Py::new(py, buffctrl)?)
             })
         })
     }
@@ -93,12 +92,13 @@ impl PyClientHandle {
         let rc = self.0.clone();
 
         pyo3_asyncio::tokio::future_into_py(py, async move {
-            let curctrl = rc.join(session.as_str())
+            let curctrl: PyCursorController = rc.join(session.as_str())
                 .await
-                .map_err(PyCodempError::from)?;
+                .map_err(PyCodempError::from)?
+                .into();
 
             Python::with_gil(|py| {
-                Ok(Py::new(py, PyCursorController(curctrl))?)
+                Ok(Py::new(py, curctrl)?)
             })
         })
     }
@@ -107,12 +107,13 @@ impl PyClientHandle {
         let rc = self.0.clone();
 
         pyo3_asyncio::tokio::future_into_py(py, async move {
-            let curctrl = rc.get_cursor()
+            let curctrl: PyCursorController = rc.get_cursor()
                 .await
-                .map_err(PyCodempError::from)?;
+                .map_err(PyCodempError::from)?
+                .into();
 
             Python::with_gil(|py| {
-                Ok(Py::new(py, PyCursorController(curctrl))?)
+                Ok(Py::new(py, curctrl)?)
             })
         })
     }
@@ -121,12 +122,13 @@ impl PyClientHandle {
         let rc = self.0.clone();
 
         pyo3_asyncio::tokio::future_into_py(py, async move {
-            let buffctrl = rc.get_buffer(path.as_str())
+            let buffctrl: PyBufferController = rc.get_buffer(path.as_str())
                 .await
-                .map_err(PyCodempError::from)?;
+                .map_err(PyCodempError::from)?
+                .into();
 
             Python::with_gil(|py| {
-                Ok(Py::new(py, PyBufferController(buffctrl))?)
+                Ok(Py::new(py, buffctrl)?)
             })
         })
     }
@@ -154,20 +156,30 @@ impl PyClientHandle {
     }
 }
 
-impl From::<CodempCursorController> for PyCursorController {
-    fn from(value: CodempCursorController) -> Self {
-        PyCursorController(Arc::new(value))
-    }
-}
-
-impl From::<CodempBufferController> for PyBufferController {
-    fn from(value: CodempBufferController) -> Self { 
-        PyBufferController(Arc::new(value))
-    }
-}
-
 #[pyclass]
-struct PyCursorController(Arc<CodempCursorController>);
+struct PyCursorController {
+    handle: Arc<CodempCursorController>,
+    cb_trigger: Option<tokio::sync::mpsc::UnboundedSender<()>>
+}
+
+impl From::<Arc<CodempCursorController>> for PyCursorController {
+    fn from(value: Arc<CodempCursorController>) -> Self {
+        PyCursorController {
+            handle: value,
+            cb_trigger: None
+        }
+    }
+}
+
+fn py_cursor_callback_wrapper(cb: PyObject) 
+    -> Box<dyn FnMut(CodempCursorEvent) -> () + Send + Sync + 'static>
+{
+    let closure = move |data: CodempCursorEvent| {
+        let args: PyCursorEvent = data.into();
+        Python::with_gil(|py| { let _ = cb.call1(py, (args,)); });
+    };
+    Box::new(closure)
+}
 
 #[pymethods]
 impl PyCursorController {
@@ -193,13 +205,39 @@ impl PyCursorController {
     //         Ok(())
     //     })
     // }
+    fn drop_callback(&mut self) -> PyResult<()> {
+        if let Some(channel) = &self.cb_trigger {
+            channel.send(())
+                .map_err(CodempError::from)
+                .map_err(PyCodempError::from)?;
+
+            self.cb_trigger = None;
+        }
+        Ok(())
+    }
+
+    fn callback<'a>(&'a mut self, py_cb: Py<PyAny>) -> PyResult<()> {
+        if let Some(_channel) = &self.cb_trigger {
+            Err(PyCodempError::from(CodempError::InvalidState { msg: "A callback is already running.".into() }).into())
+        } else {
+            let rt = pyo3_asyncio::tokio::get_runtime();
+
+            // create a channel to stop the callback task running on the tokio runtime.
+            // and save the sendent inside the python object, so that we can later call it.
+            let (tx, rx) = tokio::sync::mpsc::unbounded_channel();
+            self.cb_trigger = Some(tx);
+
+            self.handle.callback(rt, rx, py_cursor_callback_wrapper(py_cb));
+            Ok(())
+        }
+    }
 
     fn send<'a>(&'a self, py: Python<'a>, path: String, start: (i32, i32), end: (i32, i32)) -> PyResult<&'a PyAny> {
-        let rc = self.0.clone();
+        let rc = self.handle.clone();
         let pos = CodempCursorPosition {
             buffer: path,
-            start: Some(CodempRowCol { row: start.0, col: start.1 }),
-            end: Some(CodempRowCol { row: end.0, col: end.1 })
+            start: Some(start.into()),
+            end: Some(end.into())
         };
 
         pyo3_asyncio::tokio::future_into_py(py, async move {
@@ -210,19 +248,63 @@ impl PyCursorController {
 
     }
 
+    fn try_recv(&self, py: Python<'_>) -> PyResult<PyObject> {
+        match self.handle.try_recv().map_err(PyCodempError::from)? {
+            Some(cur_event) => {
+                let evt = PyCursorEvent::from(cur_event);
+                Ok(evt.into_py(py))
+            },
+            None => Ok(py.None())
+        }
+    }
+
     fn recv<'a>(&'a self, py: Python<'a>) -> PyResult<&'a PyAny> {
-        let rc = self.0.clone();
+        let rc = self.handle.clone();
 
         pyo3_asyncio::tokio::future_into_py(py, async move {
-            let cur_event = rc.recv()
+            let cur_event: PyCursorEvent = rc.recv()
                 .await
-                .map_err(PyCodempError::from)?;
-            Ok(())
+                .map_err(PyCodempError::from)?
+                .into();
+            Python::with_gil(|py| {
+                Ok(Py::new(py, cur_event)?)
+            })
+        })
+    }
+
+    fn poll<'a>(&'a self, py: Python<'a>) -> PyResult<&'a PyAny> {
+        let rc = self.handle.clone();
+
+        pyo3_asyncio::tokio::future_into_py(py, async move {
+            Ok(rc.poll().await.map_err(PyCodempError::from)?)
         })
     }
 }
+
 #[pyclass]
-struct PyBufferController(Arc<CodempBufferController>);
+struct PyBufferController {
+    handle: Arc<CodempBufferController>,
+    cb_trigger: Option<tokio::sync::mpsc::UnboundedSender<()>>
+}
+
+impl From::<Arc<CodempBufferController>> for PyBufferController {
+    fn from(value: Arc<CodempBufferController>) -> Self { 
+        PyBufferController{
+            handle: value,
+            cb_trigger: None
+        }
+    }
+}
+
+fn py_buffer_callback_wrapper(cb: PyObject) 
+    -> Box<dyn FnMut(CodempTextChange) -> () + Send + Sync + 'static>
+{
+    let closure = move |data: CodempTextChange| {
+        let args: PyTextChange = data.into();
+        Python::with_gil(|py| { let _ = cb.call1(py, (args,)); });
+    };
+    Box::new(closure)
+}
 
 #[pymethods]
 impl PyBufferController {
@@ -250,40 +332,150 @@ impl PyBufferController {
     //     })
     // }
 
+    fn drop_callback(&mut self) -> PyResult<()> {
+        if let Some(channel) = &self.cb_trigger {
+            channel.send(())
+                .map_err(CodempError::from)
+                .map_err(PyCodempError::from)?;
+
+            self.cb_trigger = None;
+        }
+        Ok(())
+    }
+
+    fn callback<'a>(&'a mut self, py_cb: Py<PyAny>) -> PyResult<()> {
+        if let Some(_channel) = &self.cb_trigger {
+            Err(PyCodempError::from(CodempError::InvalidState { msg: "A callback is already running.".into() }).into())
+        } else {
+            let rt = pyo3_asyncio::tokio::get_runtime();
+
+            // could this be a oneshot channel?
+            let (tx, rx) = tokio::sync::mpsc::unbounded_channel();
+            self.cb_trigger = Some(tx);
+
+            self.handle.callback(rt, rx, py_buffer_callback_wrapper(py_cb));
+            Ok(())
+        }
+    }
+
+
+    fn replace(&self, txt: &str) -> PyResult<()> {
+        if let Some(op) = self.handle.replace(txt) {
+            self.handle.send(op).map_err(PyCodempError::from)?;
+        }
+        Ok(())
+    }
+
+    fn delta(&self, start: usize, txt: &str, end: usize) -> PyResult<()> {
+        if let Some(op) = self.handle.delta(start, txt, end){
+            self.handle.send(op).map_err(PyCodempError::from)?;
+        }
+        Ok(())
+    }
+
+    fn insert(&self, txt: &str, pos: u64) -> PyResult<()> {
+        let op = self.handle.insert(txt, pos);
+        self.handle.send(op).map_err(PyCodempError::from)?;
+        Ok(())
+    }
+
+    fn delete(&self, pos: u64, count: u64) -> PyResult<()> {
+        let op = self.handle.delete(pos, count);
+        self.handle.send(op).map_err(PyCodempError::from)?;
+        Ok(())
+    }
+
+    fn cancel(&self, pos: u64, count: u64) -> PyResult<()> {
+        let op = self.handle.cancel(pos, count);
+        self.handle.send(op).map_err(PyCodempError::from)?;
+        Ok(())
+    }
+
     fn content(&self, py: Python<'_>) -> PyResult<Py<PyString>> {
-        let cont: Py<PyString> = PyString::new(py, self.0.content().as_str()).into();
+        let cont: Py<PyString> = PyString::new(py, self.handle.content().as_str()).into();
         Ok(cont)
     }
 
-    fn send<'a>(&self, py: Python<'a>, skip: usize, text: String, tail: usize) -> PyResult<&'a PyAny>{
-        let rc = self.0.clone();
+    // What to do with this send? does it make sense to implement it at all?
+    // fn send<'a>(&self, py: Python<'a>, skip: usize, text: String, tail: usize) -> PyResult<&'a PyAny>{
+    //     let rc = self.handle.clone();
+    //     pyo3_asyncio::tokio::future_into_py(py, async move {
+    //         Ok(())
+    //     })
+    // }
+
+    fn try_recv(&self, py: Python<'_>) -> PyResult<PyObject> {
+        match self.handle.try_recv().map_err(PyCodempError::from)? {
+            Some(txt_change) => {
+                let evt = PyTextChange::from(txt_change);
+                Ok(evt.into_py(py))
+            },
+            None => Ok(py.None())
+        }
+    }
+
+    fn recv<'a>(&'a self, py: Python<'a>) -> PyResult<&'a PyAny> {
+        let rc = self.handle.clone();
+
         pyo3_asyncio::tokio::future_into_py(py, async move {
-            Ok(())
+            let txt_change: PyTextChange = rc.recv()
+                .await
+                .map_err(PyCodempError::from)?
+                .into();
+            Python::with_gil(|py| {
+                Ok(Py::new(py, txt_change)?)
+            })
         })
-    } 
+    }
+
+    fn poll<'a>(&'a self, py: Python<'a>) -> PyResult<&'a PyAny> {
+        let rc = self.handle.clone();
+
+        pyo3_asyncio::tokio::future_into_py(py, async move {
+            Ok(rc.poll().await.map_err(PyCodempError::from)?)
+        })
+    }
 }
 
-// #[pyclass]
-// struct PyCursorEvent {
-//     user: String,
-//     buffer: Some(String),
-//     start: (i32, i32),
-//     end: (i32, i32)
-// }
+/* ---------- Type Wrappers ----------*/
+// All these objects are not meant to be handled rust side.
+// Just to be sent to the python heap.
 
-// impl From<CodempCursorEvent> for PyCursorEvent {
-//     fn from(value: CodempCursorEvent) -> Self {
-//         PyCursorEvent { 
-//             user: value.user,
-//             buffer: value.position.buffer,
-//             start: (value.position.start.row, value.position.start.col),
-//             end: (value.position.end.row, value.position.end.col) 
-//         }
-//     }
-// }
+#[pyclass]
+struct PyCursorEvent {
+    user: String,
+    buffer: String,
+    start: (i32, i32),
+    end: (i32, i32)
+}
 
+impl From<CodempCursorEvent> for PyCursorEvent {
+    fn from(value: CodempCursorEvent) -> Self {
+        // todo, handle this optional better?
+        let pos = value.position.unwrap_or_default();
+        PyCursorEvent {
+            user: value.user,
+            buffer: pos.buffer,
+            start: pos.start.unwrap_or_default().into(),
+            end: pos.end.unwrap_or_default().into()
+        }
+    }
+}
 
-// Python module
+#[pyclass]
+struct PyTextChange {
+    start_incl: usize,
+    end_excl: usize,
+    content: String
+}
+
+impl From<CodempTextChange> for PyTextChange {
+    fn from(value: CodempTextChange) -> Self {
+        PyTextChange { start_incl: value.span.start, end_excl: value.span.end, content: value.content }
+    }
+}
+
+/* ------ Python module --------*/
 #[pymodule]
 fn codemp_client(_py: Python, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(codemp_init, m)?)?;
@@ -291,5 +483,10 @@ fn codemp_client(_py: Python, m: &PyModule) -> PyResult<()> {
     m.add_class::<PyCursorController>()?;
     m.add_class::<PyBufferController>()?;
 
+    m.add_class::<PyCursorEvent>()?;
+    m.add_class::<PyTextChange>()?;
+
     Ok(())
-}
\ No newline at end of file
+}
+
+