[SNMP4J] Updating registered managed objects (adding rows to MIB table)
Marek Hajduczenia
marek.hajduczenia at gmail.com
Wed Feb 27 03:37:38 CET 2013
Thank you, Frank.
That is what was missing in the overall picture of things. I successfully
added the function to update the registered MIB table, adding and removing
values, reflecting the changes in the observed folder on the drive.
A separate question but in the same context. The MIB I am working on
contains an entry which can be set remotely. When set to true, action is
supposed to take place and the agent should execute local software (in the
case of the project in question, fire up VLC player and start streaming the
selected music file). I was wondering whether there is any way to detect
changes in the MIB done remotely (some field being modified via SET command)
and if so, how to get around to coding such a function.
Any pointers to code snippets would be most welcome.
Thank you in advance
Marek
-----Original Message-----
From: Frank Fock [mailto:fock at agentpp.com]
Sent: Tuesday, 26 February, 2013 11:41 PM
To: Marek Hajduczenia
Cc: snmp4j at agentpp.org
Subject: Re: [SNMP4J] Updating registered managed objects (adding rows to
MIB table)
Marek,m,
Any operation on the model is immediately visible (add, remove, and update).
No deregister/register is needed/feasable.
Best regards,
Frank
Am 27.02.2013 00:13, schrieb Marek Hajduczenia:
> Frank,
>
> I must have missed it. Sorry about that.
>
> This solves the problem of adding rows to a registered table. I assume
> similarly one could also remove rows (removeRow function). However,
> when such updates are done on an already registered table, the state
> of the table is updated automatically (newly added rows become
> accessible immediately when added) or I need to deregister the table and
register it again ?
>
> Marek
>
> -----Original Message-----
> From: Frank Fock [mailto:fock at agentpp.com]
> Sent: Tuesday, 26 February, 2013 11:02 PM
> To: Marek Hajduczenia
> Cc: snmp4j at agentpp.org
> Subject: Re: [SNMP4J] Updating registered managed objects (adding rows
> to MIB table)
>
> Marek,
>
> "Can I just use addRow on the MOMutableTableModel type?"
> Yes, that's what I wrote.
>
> Best regards,
> Frank
>
> Am 26.02.2013 23:58, schrieb Marek Hajduczenia:
>> Frank,
>>
>> Here is the code snippet for the main class (snmpAgentClientMain.java):
>> http://snipt.org/zfhab7. The agent code starts in line 110, MIB table
>> is constructed in lines 129 (using MOTableBuilder class) and
>> createMibTable function defined in snmpAgentClientMain class. The
>> MOTableBuilder.java
> class
>> is snipped at http://snipt.org/zfhac3 and it is used to build the
>> table structure in a more organized fashion.
>>
>> Looking through the code of the MOTableBuilder class, and seeing how
>> it is used in snmpAgentClientMain class (line
>> server.registerManagedObject(builder.build());), I am not cure how
>> to add more row values to the table that was constructed using either
>> the MOTableBuilder wrapper or using just functions defined in snmp4j
library.
> At
>> some point of time, MOTable has to be created (its structure
>> defined), row values are added (I assume it is done using addRow
>> function from snmp4j class), and then registered with the agent
>> (server.registerManagedObject() function). Once it is registered, is
>> there any way to just add rows with values to the previously
>> registered MIB table? Can I just use addRow on
> the
>> MOMutableTableModel type?
>>
>> Marek
>>
>> -----Original Message-----
>> From: snmp4j-bounces at agentpp.org [mailto:snmp4j-bounces at agentpp.org]
>> On Behalf Of Frank Fock
>> Sent: Tuesday, 26 February, 2013 10:00 PM
>> To: snmp4j at agentpp.org
>> Subject: Re: [SNMP4J] Updating registered managed objects (adding
>> rows to MIB table)
>>
>>
>> Hi Marek,
>>
>> I do not know a "addRowValue" command and what is a "builder"?
>> I meant to use the
>> http://www.snmp4j.org/agent/doc/org/snmp4j/agent/mo/MOTable.html#addR
>> ow(R)
>> method to add a row.
>> A table definition (MIB specification) never has any rows.
>>
>> Best regards,
>> Frank
>>
>> Am 26.02.2013 18:39, schrieb Marek Hajduczenia:
>>> Hi Frank,
>>>
>>>
>>>
>>> thanks for the quick feedback. I must have not been really clear in
>>> my explanation and I apologize for that. What I want to achieve is
>>> not to
> add
>>> new rows into the table definition, but add new entries (new rows
>>> using addRowValue command) into the table.
>>>
>>>
>>>
>>> In other words, how do I add row values (addRowValue) to builder
>>> after having executed
>>>
>>>
>>>
>>> server.registerManagedObject(builder.build());
>>>
>>>
>>>
>>> ?
>>>
>>>
>>>
>>> When I try to add row values using builder.addRowValue and then
>>> register
>> the
>>> MO again, I get exception (quite expected, it is registered already)
>>>
>>>
>>>
>>> Thanks again
>>>
>>>
>>>
>>> Marek
>>>
>>>
>>>
>>>> Hi,
>>>> The answer is very simple: Just add rows to the table (i.e. its
>>>> table model).
>>>> You can do this while the table itself is registered (operation is
>>>> thread safe).
>>>> Best regards,
>>>> Frank
>>>
>>>
>>>
>>> Subject: Updating registered managed objects (adding rows to MIB
>>> table)
>>>
>>>
>>>
>>> Dear all,
>>>
>>>
>>>
>>> I am writing a small SNMP related project for my course. The task is
>>> to create an SNMP agent that will monitor a local selected folder
>>> and list
>> all
>>> files stored in this folder in a MIB. I have already MIB designed,
>>> agent working fine on the initial pass, i.e., it creates a MIB
>>> table, populates initial values (files found at first pass through
>>> the folder) and then registers MIB with the agent.
>>>
>>>
>>>
>>> The code snippet building the table structure is shown below:
>>>
>>>
>>>
>>> MOTableBuilder builder = new MOTableBuilder(oidNewRoot);
>>>
>>>
>>>
>>> // MIB structure
>>>
>>>
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_INTEGER32,MOAccessImpl.ACCES
> S_READ
>>> _ONLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_OCTET_STRING,MOAccessImpl.AC
> CESS_R
>>> EAD_ONLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_INTEGER,MOAccessImpl.ACCESS_
> READ_O
>>> NLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_OCTET_STRING,MOAccessImpl.AC
> CESS_R
>>> EAD_ONLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_INTEGER32,MOAccessImpl.ACCES
> S_READ
>>> _ONLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_INTEGER32,MOAccessImpl.ACCES
> S_READ
>>> _ONLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_OCTET_STRING,MOAccessImpl.AC
> CESS_R
>>> EAD_ONLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_OCTET_STRING,MOAccessImpl.AC
> CESS_R
>>> EAD_ONLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_INTEGER32,MOAccessImpl.ACCES
> S_READ
>>> _ONLY);
>>>
>>>
> builder.addColumnType(SMIConstants.SYNTAX_INTEGER,MOAccessImpl.ACCESS_
> READ_W
>>> RITE);
>>>
>>>
>>>
>>> The code snippet adding a row is shown below (it is repeated in a
>>> loop to add all found files):
>>>
>>>
>>>
>>> builder.addRowValue(new Integer32(index));
>>>
>>> index++;
>>>
>>> builder.addRowValue(new OctetString(fileName.getName()));
>>>
>>> builder.addRowValue(new Integer32(3));
>>>
>>> builder.addRowValue(new OctetString(fileName.getPath()));
>>>
>>> builder.addRowValue(new Integer32((int)fileName.length()));
>>>
>>> builder.addRowValue(new Integer32(323));
>>>
>>> builder.addRowValue(new OctetString("Artista"));
>>>
>>> builder.addRowValue(new OctetString("Album"));
>>>
>>> builder.addRowValue(new Integer32(1980));
>>>
>>> builder.addRowValue(new Integer32(4));
>>>
>>>
>>>
>>> Finally, I register the new MIB with the agent:
>>>
>>>
>>>
>>> server.registerManagedObject(builder.build());
>>>
>>>
>>>
>>> After that, I run agent on a loop, every 5 seconds checking whether
>>> a new file was added to the folder. When that happens, I can detect
>>> a new file added and create list of such files. However, I do not
>>> know (could not
>> find
>>> any information) on how to add row to already registered MIB. One
>>> thought was on reusing previously constructed table and just
>>> deregister it, then
>> add
>>> new rows as needed and the register again but it seems like a very
>>> crude solution to me. Is there any way to do that better? if so, I
>>> would appreciate any pointers.
>>>
>>>
>>>
>>> Thank you in advance
>>>
>>>
>>>
>>> Marek
>>>
>>>
>>>
>>> _______________________________________________
>>> SNMP4J mailing list
>>> SNMP4J at agentpp.org
>>> http://lists.agentpp.org/mailman/listinfo/snmp4j
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