[SNMP4J] Concurrent requests for multiple agents.

[Lilach Refaeli]

Thanks Frank,

I changed the code to work with a single addition of USM user, but I'm
still getting the Not-In-Time-Windows OID from time to time.

The code of adding the user is:

	private synchronized void  addUsmUser(
			Snmp snmp,
			String securityName,
			OID authProtocol,
			String authPassphrase,
			OID privacyProtocol,
			String privacyPassphrase
			) {
  	
		USM usm = snmp.getUSM();
		
		// If not exists, Add the user model to the security
model.
		if (usm==null) {

			byte[] localEngineID  =
MPv3.createLocalEngineID();
		
			usm = new USM(
				SecurityProtocols.getInstance(),
				new OctetString(localEngineID),0);
				
	
SecurityModels.getInstance().addSecurityModel(usm);
		}
		
		OctetString securityOctString = null ;
		OctetString authPassphraseOctString = null;
		OctetString privacyPassphraseOctString = null;
	
		if(securityName != null){
			securityOctString = new OctetString
(securityName);
		}
		if(authPassphrase != null){
			authPassphraseOctString = new
OctetString(authPassphrase);
		}
		if(privacyPassphrase != null){
			privacyPassphraseOctString = new
OctetString(privacyPassphrase);
		}

		// Add USM user to the security model
		
		if (usm.getUserTable().getUser(securityOctString)==null)
		{	
		
			// Add user to the user list of the SNMP object
		
			UsmUser usmUser = new UsmUser(
				securityOctString,
				authProtocol,
				authPassphraseOctString,
				privacyProtocol,
				privacyPassphraseOctString);
		
		
	
snmp.getUSM().addUser(securityOctString,usmUser);
			
		}
	}

Do you have any idea what might be the reason? 

Thanks a lot,
Lilach

-----Original Message-----
From: Frank Fock [mailto:fock at agentpp.com] 
Sent: Wednesday, May 18, 2005 10:25 AM
To: Lilach Refaeli
Cc: snmp4j at agentpp.org
Subject: Re: [SNMP4J] Concurrent requests for multiple agents.

Hi Lilach,

Lilach Refaeli wrote:

>I have a multi-threaded Application, which sends requests to different
>agents concurrently (synchronously).
>
>It uses one instance of the SNMP object.
>
>The USM user parameters (authentication passphrase, authentication
>protocol ID, etc.) of all the agents are identical.   
>
>My question is: 
>
>Should I add a USM user for each agent?  How would the SNMP object know
>  
>
No, since all your your user and password pairs are identical, you only
add the user once. Otherwise, if you add it (non localized - thus 
without engine ID)
at a later time other requests running concurrently will see timeouts 
out of time
window errors.

>which USM user to use for the sending operation?  (When is the agent-ID
>discovery process activated?)
>
>  
>
The engine ID of a target is discovered when a request is sent to it and

there is
no engine ID known for that target.

>Is there a way to explicitly perform the agent ID discovery? (To add a
>user and associate it with a specific engine ID)
>
>  
>
Yes, you can disable engine ID discovery at the USM class and use
MPv3.getEngineID(Address addr) to discover the engine ID.

> 
>
>When I add a USM user with no agent ID parameter and send requests
>concurrently, I get an usmStatsNotInTimeWindows response or a timeout
>occurs. 
>
> 
>  
>
This can be caused by updating the user while requests are currently 
processed
(or if some of the targets share the same engine ID - but that should 
not be the case).

Best regards,
Frank