* - send/receive bytes or string data to/from the data channel
* - get notified various states of the data channel
*
+ * @subsection CAPI_MEDIA_WEBRTC_DATA_CHANNEL_CALLBACK_OPERATIONS Callback(Event) Operations
+ * The callback mechanism is used to notify the application about significant webrtc data channel events.
+ * <div><table class="doxtable" >
+ * <tr>
+ * <th><b>REGISTER</b></th>
+ * <th><b>UNREGISTER</b></th>
+ * <th><b>CALLBACK</b></th>
+ * <th><b>DESCRIPTION</b></th>
+ * </tr>
+ * <tr>
+ * <td>webrtc_set_data_channel_cb()</td>
+ * <td>webrtc_unset_data_channel_cb()</td>
+ * <td>webrtc_data_channel_cb()</td>
+ * <td>This callback is used to notify that a data channel is created to the connection by the remote peer</td>
+ * </tr>
+ * <tr>
+ * <td>webrtc_data_channel_set_open_cb()</td>
+ * <td>webrtc_data_channel_unset_open_cb()</td>
+ * <td>webrtc_data_channel_open_cb()</td>
+ * <td>This callback is used to notify that the data channel is opened</td>
+ * </tr>
+ * <tr>
+ * <td>webrtc_data_channel_set_message_cb()</td>
+ * <td>webrtc_data_channel_unset_message_cb()</td>
+ * <td>webrtc_data_channel_message_cb()</td>
+ * <td>This callback is used to notify that a message is received from the data channel</td>
+ * </tr>
+ * <tr>
+ * <td>webrtc_data_channel_set_error_cb()</td>
+ * <td>webrtc_data_channel_unset_error_cb()</td>
+ * <td>webrtc_data_channel_error_cb()</td>
+ * <td>This callback is used to notify that an error occurs from the data channel</td>
+ * </tr>
+ * <tr>
+ * <td>webrtc_data_channel_set_close_cb()</td>
+ * <td>webrtc_data_channel_unset_close_cb()</td>
+ * <td>webrtc_data_channel_close_cb()</td>
+ * <td>This callback is used to notify that the data channel is closed</td>
+ * </tr>
+ * <tr>
+ * <td>webrtc_data_channel_set_buffered_amount_low_cb()</td>
+ * <td>webrtc_data_channel_unset_buffered_amount_low_cb()</td>
+ * <td>webrtc_data_channel_buffered_amount_low_cb()</td>
+ * <td>This callback is used to notify that the number of bytes of data currently queued to be sent over the data channel falls below the threshold</td>
+ * </tr>
+ * </table></div>
+ *
*/
/**