[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: snmpconf Proposed agenda for interim meeting



In the paragraphs I have excerpted, you raise two questions I would like to 
comment on:
1) "The operator / implementor can choose the policy expression language 
they prefer".  This actually seems counter-productive.  If I am trying to 
epxress policies across devices, and different device implementors have 
implements different expression languages, I do not get close to what I 
want.  I do note that later you suggest we might use the script MIB 
technology, but remove the language choice.

2) You express concern about the iteration implicitr in the current 
environment.  There seem to be two sides to this coin.  One side says taht 
magic iteration is usually dangers.  The other side says that writing 
scripts which control the iteration, and explicitly specify the 
rescheduling of the operation of the scripts, and additional the validity 
time windows of the scripts, and the scratchpads for the scripts, etc... is 
prone to significant complication.  It seems to me that it is important to 
provide some easy way to get the common cases of iteration and repetition 
of policy checking.  But I am not sure where the line falls on this.

Yours,
Joel M. Halpern

At 12:31 PM 10/18/00 -0400, David Harrington wrote:
>Using the Script MIB, the operator/implementor can choose the policy
>expression language they prefer, that is supported by the managed
>device. The application is a general purpose interpreter, so the
>expression of the policy (the script) must then be more explicit and
>contain more of the logic, such as the iteration across the managed
>elements.
>
>One concern I have about the snmpconf language is the dependence on
>"magic" for the iteration; somehow the snmpconf engine "knows" how to
>iterate across the possible managed elements. It has been my experience
>as a programmer that computers are very poor at "knowing" what I intend;
>they only "know" what I tell them explicitly. I think it will become
>necessary to include iterator statements in our policies, or we will
>need to rely on some level of magic for the thing to work.
>
>It would be helpful to standardize the expression formats that can be
>used for policy. Snmpconf WG could design a "language" for policy
>expressions (as we are currently doing). Those expressions could be put
>into scripts that could be downloaded to the device by disman, then
>executed within an snmpconf runtime environment. The only differences
>here are using combination statements rather than separate conditions
>and actions, and the method of downloading the policy to the managed
>device. If we work at it, we could make the snmpconf approach compatible
>with the Script MIB rather than reinventing the wheel. If we make our
>design caompatible with disman, then users who like our
>policy-expression language and runtime environment can use it within a
>DISMAN environment; if they'd rather do policy using perl or javascript,
>they could use that within a disman environment; maybe they'd use a
>combination of perl and javascript and snmpconf-expressions to best meet
>their needs.