On Monday 25 June 2007 19:22:45 Juuso Alasuutari wrote:
> Next up in my small monitor app project is to learn how to get snmp data
> from devices at constant intervals. I expanded the example application
> (http://www.net-snmp.org/wiki/index.php/TUT:Simple_Application) into
> something that can be described with a little pseudocode:
>
>
> init_snmp( "foo" )
>
> while {
> for each device, do {
> ss[device] <- snmp_open( session[device] )
> pdu[device] <- snmp_pdu_create( SNMP_MSG_GET )
> read_objid( oid[device], temp_oid, len )
> snmp_add_null_var( pdu[device], temp_oid, len )
> }
>
> for each device, do {
> status = snmp_synch_response ( ss[device], pdu[device], response )
> if (status == OK) {
> do stuff with response
> }
> snmp_free_pdu( response )
> response <- NULL
> free( ss[device] )
> ss[device] <- NULL
> }
>
> for each device, do {
> snmp_close ( ss[device] )
> }
>
> sleep (n_seconds)
> }
>
>
> It seems to work OK, but then again when I left it running on a server it
> had quietly exited after maybe 20 minutes. Although I armed it with
> debugging printfs I didn't see any specific error in the log, it had simply
> quit. But my most important question at this point is if this whole
> approach is appropriate for my needs or if I need to study some helpful
> manual.
I solved this problem by moving some parts of the code outside the loop. I
noticed that the client always exited when it had looped exactly 1021
requests. I don't know where that number is from. Here's the pseudocode
representation of what seems to work:
init_snmp( "foo" )
for each device, do {
ss[device] <- snmp_open( session[device] )
}
while( something ) {
for each device, do {
pdu[device] <- snmp_pdu_create( SNMP_MSG_GET )
read_objid( oid[device], temp_oid, len )
snmp_add_null_var( pdu[device], temp_oid, len )
}
for each device, do {
status = snmp_synch_response ( ss[device], pdu[device], response )
if (status == OK) {
do stuff with response
}
if (response) {
snmp_free_pdu( response )
response <- NULL
}
}
sleep (n_seconds)
}
for each device, do {
snmp_close ( ss[device] )
}
Juuso
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