[Tinyos-devel] Re: [Tinyos-help] CTP + LPL

[Philip Levis]

On Feb 5, 2008, at 5:26 AM, David Moss wrote:

> I just added a hook to the CC2420 radio stack in CVS to configure  
> an outbound message. The interface is called SendNotifier, and has  
> a single event:
>
>
>
>   event void aboutToSend(am_addr_t addr, message_t *msg);
>
>
>
> This event is provided by CC2420ActiveMessageC, and is  
> parameterized by am_id_t.
>
>
>
> You can access this interface to configure packets sent by any  
> module in your application, modifying the outbound packet based on  
> AM type, destination, etc.  The main intention is CTP + LPL  
> integration (with examples attached – modify as necessary), but you  
> can use it to add all sorts of system-wide functionality to your  
> application.  Here’s a small example:
>
>
>
>   event void SendNotifier.aboutToSend[AM_CTP_DATA](am_addr_t addr,  
> message_t *msg) {
>
>     call LowPowerListening.setRxSleepInterval(msg, 512);
>
>   }
>
>
>
> Simply create a module that defines an LPL policy for your system,  
> and use the SendNotifier interface to enforce it.
>
>
>
> If this hook works out, we can extend this to other radio stacks as  
> necessary
>

This is a bit weird. Why should the sleep interval be controlled by a  
single layer 3 protocol? On the receiver side, it must somehow be  
determined across all of the layer 3 protocols. If anything, this  
seems something that should *not* be parameterized, so that a -- to  
borrow the SP nomenclature -- a policy manager can decide what to do.

Phil