[SNMP4j] getTable Issues [a] version1 vs version2c [b] null pointer

[Frank Fock]

Colin,

A: This issue is most likely related to your agent. Please check the
response PDU received from the agent for correct version and
request ID.

B: The agent probably does not implement lexicographic ordering
correctly or it does not implement all columns for all rows. You will
have to check the Variable returned for each column if it is null or
not in order to avoid the NullPointerException.

Best regards,
Frank

Mystery Guest wrote:

> Hello,
>
> I am relatively new to Java but have some experience with networking.
> I have written some sample Java programs using SNMP4J that do both
> synchronous and asynchronous GET requests and these have worked well.
> I am now trying my hand at a synchronous table get and I have run
> into a couple of problems.  The first problem I managed to solve but
> the second one has me stumped at the moment and I am hoping that
> someone could point me in the right direction to resolve it.
>
> OS:  Solaris 10 as a VMWare guest
> Java: Java(TM) 2 Runtime Environment, Standard Edition (build 
> 1.5.0_01-b08)
> SNMP4J:  1.6b
>
> A. The first issue was that my getTable call was returning a status code
> which implied a timeout.  A snoop of the interface showed the
> request going out and a response coming back.  It was then that I noticed
> I had set my version to 1 [ target.setVersion(SnmpConstants.version1); ]
> If I changed the version to 2c then I started getting results I expected.
> Could anyone explain why this would be so?
>
> B. Now my getTable call is working and I am printing out the data from
> each TableEvent.  However, at the 19th TableEvent I am getting a
> null pointer exception.  The table event status code is 0 and a snoop
> shows the data being returned so I am at a bit of a loss to figure out
> where I have gone wrong.  I think my code is OK otherwise I would have
> expected a problem on the first iteration.  If anyone has any hints
> I would greatly appreciate it.
>
> Output:
>
> sol10a-colin[4]% ./runit SnmpTestTable
>
> ----- Start of Table Event -----
> Table event status = 0
> Index = 1
> Number of columns = 11
> 1,"FastEthernet0/1",6,1500,100000000,"00:0d:ed:75:8f:81",1,1,0:00:45.76,2561384523,9262716 
>
> ----- End of Table Event -----
>
> ----- Start of Table Event -----
> Table event status = 0
> Index = 2
> Number of columns = 11
> 2,"FastEthernet0/2",6,1500,100000000,"00:0d:ed:75:8f:82",1,1,0:00:44.68,4046297721,1826102036 
>
> ----- End of Table Event -----
>
>        .... snip ....
>
> ----- Start of Table Event -----
> Table event status = 0
> Index = 18
> Number of columns = 11
> 18,"FastEthernet0/22",6,1500,100000000,"00:0d:ed:75:8f:96",1,1,0:00:44.78,1125561467,105822311 
>
> ----- End of Table Event -----
>
> ----- Start of Table Event -----
> Table event status = 0
> Index = 19
> Number of columns = 11
> Exception in thread "main" java.lang.NullPointerException
>        at SnmpTestTable.main(SnmpTestTable.java:77)
>
> Code Snippet:
>
>   // send request
>
>   List tableEventList = tableUtils.getTable(target, oidIfTable, null, 
> null);
>
>   // dump what we have received
>
>   Iterator tableEventIter = tableEventList.iterator();
>   while (tableEventIter.hasNext()) {
>
>     TableEvent tableEvent = (TableEvent)tableEventIter.next();
>
>     System.out.println(" ");
>     System.out.println("----- Start of Table Event -----");
>     System.out.println("Table event status = "+tableEvent.getStatus());
>     System.out.println("Index = "+tableEvent.getIndex());
>     System.out.println("Number of columns = " + 
> tableEvent.getColumns().length);
>
>     for ( int i = 0; i<tableEvent.getColumns().length; i++) {
>       Variable v = tableEvent.getColumns()[i].getVariable();    <== 
> Fails here
>       String value = v.toString();
>       switch (v.getSyntax()) {
>           .... the rest of this code comes from the...
>        .... SNMP4J sample console code in the method ...
>        .... CVSTableListener ....
>
> I hope this isn't too long and that I have provided enough information.
>
> Many thanks in advance.
>
> ./Colin
>
>
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>
>


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