Re: [Agentx] Empty context in rfc2742

[Mark Ellison <[e-mail]>]

On Sun, Aug 30, 2009 at 5:17 AM, Magnus Fromreide<[e-mail]> wrote:
> Hello.
>
> According to rfc2742 agentxRegContext (octet string) is
>     "The context in which the session supports the objects in this
>      region.  A zero-length context indicates the default context.
>     "
>
> Now I am would like to know how a zero-length context should be
> represented?
>
The default context is an OCTET STRING of zero-length.   How to
represent this depends upon where it is being represented.

On the wire, the tag is "OCTET STRING" the length is zero(0) and the
value occupies no octets.  There are numerous examples of OCTET
STRINGs that may be zero-length in IETF standard MIB modules.

For example, in the UsmUserTable, the usmUserPublic may be a
zero-length string.  In the USM MIB module, tthe usmUserPublic object
definition shows he zero-length string as represented by the DEFVAL
clause:  { ''H }  -- the empty string.

A zero-length string and the empty-string are synonymous.

- Mark
http://EllisonSoftware.com