Trap handling

Hi,
 
We have a requirement to support trap handling in our project.
 
Requirement is whenever a trap is received a function should be called
which extracts the community string and performs some operation. 
 
With were able to do it with scotty(opening  a listener session and
binding it with a callback function. Please see the code below). 
 
set session [Tnm::snmp listener -port 162  -version SNMPv1 -transport
udp -tags {}]
$session bind trap { 
set pdu "%V" 
set community "%C"
}
 
How can the same functionality be achieved using net-snmp(a callback
function should be called whenever a trap is received).
 
I read about snmptrapd and snmptrapd.conf, but I am not sure how to use
it to achieve the above functionality.
 
Can anybody help me with this problem?
 
 

Thanks in advance 

Regards,
Sushma