[AGENT++] Proposal: Explicit save of persistent objects via SNMP

[Marek Malowidzki]

Sorry for "jumping in" in the middle but I think we would be very interested
in this feature.

> Hi Henning.
>
> I am still thinking about the MIB extension needed to best support
> dynamic configuration storage. First I thought, it could be a valuable
> feature to be able to specify which parts of the agent's MIB to store
> where. But the more I think about it, the more I doubt that this
> is really useful. What do you think?

I think this would be useful. Some parts of a MIB are built dynamically at
startup (for example, on the basis of hardware configuration) and there is
no need to store them. Additionally, some embedded systems have serious disk
space limitations and in this case one has to decide what to store. So, to
go a bit further, it would be valuable to be able to assess disk space
requirements fow a table row (on the basis of a MIB definition).

> Another option would be to schedule configuration storage. Probably,
> storing the configuration each hour or each night could be useful,
> couldn't it?

A few more things to consider:
- human-readable format
- serialization that can survive power failures (e.g., which occur during
serialization)
- an internal API to enforce serialization "at the nearest occasion" (see
below)
- some limit to how often serialization can be done (once again, in case an
embedded system uses a flash disk) - to limit multiple immediate writes that
occur one after another
- (I am not really aware of programming model details of Agent++ so maybe
this is already possible) a callback called on a table at startup after the
table has been completely read from disk (so configuration settings may be
enforced elsewhere)

Marek

> Thanks,
> Frank
>
>
> Frank Fock wrote:
>
> > Hi Henning,
> >
> > I am currently working on the MIB. I will be able to
> > post my proposal here later this week. My proposal
> > will be table based and open for other/future persistent
> > storage formats/types like XML or SQL.
> >
> > Best regards,
> > Frank
> >
> > Henning Eggers wrote:
> >
> >> Hi Frank!
> >>
> >>
> >>
> >>> I like your idea and I have to admit that I regret that it wasn't
mine!
> >>>
> >>
> >> ;-)
> >> Thanks for the compliment!
> >>
> >>
> >>
> >>> Within the next day(s) I will create a new revision of the
> >>> AGENTPP_CONFIG_MIB with a proposal for the new functions
> >>> you have enumerated.
> >>>
> >>
> >>
> >> I have already done this (in another MIB) and could easily move this
> >> to the
> >> AGENTPP_CONFIG_MIB. Shall I do this and post it here for discussion?
> >>
> >>
> >>
> >>> As an extension of your ideas I will check if providing a backup
config
> >>> directory is also possible.
> >>>
> >>
> >>
> >> Do you mean to leave the persistent path readonly and provide an extra
> >> read/write object for the backup path? Sounds good. The action object
> >> would
> >> then have to be extended to include saveBackup(4) and restoreBackup(5).
> >>
> >> Another extension I played with in my mind was to be able to specify
the
> >> MIB-Module or subtree to save to file. There is a list of MibGroup
> >> objects
> >> in the Mib class that could be used to select a module. Entering a
> >> base oid
> >> for a subtree should be quite simple. But both require some work on the
> >> existing code, I guess.
> >>
> >>
> >>
> >>> I will post the MIB here, and after the communities feedback I will
> >>> implement the instrumentation.
> >>>
> >>
> >>
> >> I have already done the implementation of the objects for which I
didn't
> >> habe to change the existing code (readonly persistent path, the
> >> TimeStamp
> >> objects, the saveAll operation) which turned out quite straight
> >> forward. I
> >> can put that into the config_mib code for you to review.
> >>
> >> On the other hand you seemed quite excited to do the stuff yourself
> >> (a true
> >> coder! ;-) so I am holding back a little... :-)
> >>
> >>
> >> Cheers,
> >> Henning
> >>
> >>
> >>
> >>
> >>
> >
> >
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> >
>
>
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