Mib table and DB table

[Alex Finogenov]

Ron,

I have been working on this for a few weeks. Depending on your requirements
and complexity of the MIB (tables with AUGMENTS clause, etc.), it may be
complex.

My major requirement was to modify minimum code when a MIB is changed
(recompiled). I achieved this by subclassing  MibTable (use Decorator and
Bridge design patterns) and overloading update() (you preload all the
relevant rows for the request), prepare_set_request() (here I added
additional validation, fix agent++ bugs until the new release),
commit_set_request() (here I figure out which rows have been added,
modified). Also I overloaded row_added() and row_delete() (the latter is the
only way to easily know when a row is deleted.)

The main logic is was not a problem, returning right errors and make
dependent tables (with AUGMENTS clause) work in cooperation with their base
tables is more challenging. There is also a problem of rolling back and
returning proper errors when something goes wrong in the back end systems
while everything passed fine through the SNMP agent.

You may have to write some sort of simple state machine to keep track of
what has happened and what has to happen to your tables, because the
agent++'s processing of the varbinds depends only on the sequence of them in
the request, but table independencies may force you to have your own
sequence of events (update(), prepare_set(), etc.)
To deliver the agent in a short time frame I had to go single-threaded.

Have fun,

Alex  

-----Original Message-----
From: Ron Sperber - Israel [mailto:RonS____gilat.com]
Sent: Wednesday, August 08, 2001 9:46 AM
To: 'agentpp-dl____agentpp.com'
Subject: Mib table and DB table


Hi,
I have this dilemma:
I've constructed a mib containing a table that corresponds to a dynamic
table located in an SQL server.
This table can contain up to 10,000 entries and is a dynamic one - meaning
row van be added or deleted.
My question is - since I do not want to keep all the table present in the
memory all the time (which means that I have to pass all over the DB table
once a while) I need another schema to respond with the right values.
I thought of 2 solutions
	- using the MibComplexEntry - but in this case there a lot of DB
access per request (at least in my implementation...)
	- using the usual mibTable and update the Mib in the update function
- but in this case when do I delete the entries ? I 	  can expect several
managers querying simultaneously.
Has anyone dealt with such situation?
thanks in advance ,
			Ron