Listening for Property Changes

The sensor channel APIs enable the client applications to be notified about the changes to properties associated with a sensor channel.

Steps

1. Create a property listener implementation for the MSensrvPropertyListener interface.

   class PropertyListener:public MSensrvPropertyListener
       {
       public:    
       void PropertyChanged(CSensrvChannel &aChannel, const TSensrvProperty &aChangedProperty)
           {
           ...
            //Implementation
           }
       void PropertyError(CSensrvChannel &aChannel, TSensrvErrorSeverity aError)
           {
           ...
            //Implementation
           }
       void SetPropertySuccessIndicationChanged(TSetPropertySuccessIndicator aIndication)
           {
           ...
            //Implementation
           }
       void GetPropertyListenerInterfaceL(TUid aInterfaceUid, TAny *&aInterface)
           {
           ...
            //Implementation
           }
       };

2. Start property listening by passing an instance of property listener implementation using CSensrvChannel::SetPropertyListenerL().

   //Instance of the property listener implementation
   PropertyListener propListener;
   ...
   CSensrvChannel* channel;
   ...
   channel->SetPropertyListenerL(&propListener);
   ...

   When a property change occurs, a PropertyChanged() notification is delivered through the MSensrvPropertyListener callback interface to the clients that are listening for property changes.

   Note: The client that set the property is not notified.

3. Once you get the required property changes associated with the sensor channel, you can stop property listening by passing a NULL parameter to the CSensrvChannel::SetPropertyListenerL() function.

   channel->SetPropertyListenerL();