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From Tino Schwarze <>
Subject Re: OID size limit?
Date Thu, 28 Dec 2006 15:35:55 GMT
Hi Emmanuel,

On Thu, Dec 28, 2006 at 03:56:50PM +0100, Emmanuel Lecharny wrote:

> so far, OID parts are stored in java long, so into the interval [-2^63,
> 2^63-1]. You can use up to 19 digits for an element of an OID, so your
> sample won'ty be accepted.
> If you want to generate "random" OID, what I suggest is that you store 32
> bits values separated by a '.', like :
><myprivateOID>.0.<first 32 bits value>.<second 32 bits value>.
> ... .<last 32 bits value>.

Oh, I see. That's rather cumbersome and would clutter the structure a
lot. Well, one's not supposed to parse the structure anyway...

> Do also remember that, in LDAP, OID are used to declare new attribute types,
> so creating arbitrary long OID does not make a lot of sense, but as I'm not
> aware of all the possible use-cases...
> I would be very interested to know why you need such OID values.

Well, I'd like to create an automated open-EIS to LDAP mapping. In
open-EIS we've got so-called templates (which are basically RDBMS tables
with lots of sugar and niceties like multi-language support etc.). A
template has a uniqe name called GUID, e.g. "c4u_classic_email". To
avoid having to assign a unique template OID for each open-EIS template
(extending the data model etc.), I just took the template GUID (which
consist of [a-zA-Z0-9_] and is up to 128 characters long) and converted
it to a number.

That way, the template GUID -> OID mapping is unique and I don't need a
central registry (which is rather cumbersome because third parties may
develop open-EIS modules themselves and currently, they don't need to
tell us; then they'd need to apply for template OID, wait for it etc.).

I'll try the 32-bits approach (BTW why 32 and not 42? ;-) ).

> >is there any known limitation of OID size or the size of an OID part?
> >I'm going to use auto-generated OIDs and they will look like:
> >
> >.<myprivateOID>.0.8228681198498217497059596.0.7212074495361812662326490325180684
> >
> >The OID BNF grammar doesn't specify any limits, so I'm only wondering
> >whether there are known real-life limits. Will performance be affected
> >by these monsters?




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