On Fri, 2005-04-29 at 06:12, ericyosho wrote:
> maybe have to explain:
> take scalar mplsTunnelNotificationMaxRate for example.
>
> mplsTunnelNotificationMaxRate OBJECT-TYPE
> SYNTAX Unsigned32
> MAX-ACCESS read-write
> ......
> i will first use mib2c.scalar.conf to generate a code
> template containing two functions.
>
> but i will also define a static unsigned variable in
> front of
> all the functions(here maybe
> static unsigned mplsTunnelNotificationMaxRate
Well, that's probably not a valid declaration, but
I get the general idea.
> i guess it's the way of thinking of the
> mib2c.int_watch.conf ?).
Please bear in mind that the scalar helper provides
an equivalent mechanism to the basic instance helper
(i.e. netsnmp_register_instance). It does *not*
correspond to the more specific netsnmp_register_*_instance()
calls. That's where the "watched_scalar" comes in.
(See yesterday's message).
> when registering it as a scalar, i have to do the
> coding
> with SET_RESERVE1 SET_RESERVE2 ......
> while registering it as an instance,i have got
> everything
> done after the initial function. i can just comment
> out all
> the 'MODE_GET' or 'MODE_SET_......'.
> and it works well.
You're not really giving enough detail to be clear
about exactly what you're doing. But I don't believe
that commenting out the SET or GET code in a handler
registered using "netsnmp_register_instance()" will
continue work. netsnmp_register_*_instance() perhaps,
but not the basic instance helper.
> > What are you passing to this routine, and how have
> > you declared the relevant variable?
> just the same example
> i defined an unsigned mplsTunnelNotificationMaxRate.
But unsigned *what*?
Unsigned int, unsigned long, unsigned aardvark, what?
> when i went with
> netsnmp_register_int_instance("mplsTunnelN...",
> mplsTunnelN..._oid,
> OID_LENGTH
> (mplsTunnelN..._oid),
> &mplsTunnelN...,
> NULL);
> nothing went wrong;
Which would imply that 'mplsTunnelN' was probably declared
as an "int" variable.
> but when i used
> netsnmp_register_ulong_instance()
> leaving all the args unchanged,it warned me about the
> fourth arg.
Not surprising.
The fourth argument of netsnmp_register_int_instance is
"int *it"
The fourth argument of netsnmp_register_ulong_instance is
"u_long * it"
Whichever API call you're using, you've got to declare the
variable being watched using the correct type (or conversely,
given a particular variable, you've got to use the matching
API call).
So when using netsnmp_register_int_instance, you'd declare
static int my_int_var;
When using netsnmp_register_int_instance, you'd declare
static ulong my_ulong_var;
The two types are not (or not necessarily) interchangeable.
That's one of the differences between the ns_register_*_instance
approach, and the watched_scalar helper. The instance-based
APIs provide a selection of calls, and you've got to choose
the appropriate one. The watched_scalar helper provides a
single call, and you specify the (SNMP) type involved.
Dave
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