Re: Non-existent syntax 1.3.6.1.4.1.1466.115.121.1.51 referenced (ITS#2029)

[michael@stroeder.com]

Kurt D. Zeilenga wrote:
> 
> Applications should use subschema discovery to check whether
> the server supports the schema elements they intend to use
> and, hence, already knows.

Well, let's assume an application has knowledge about how to deal 
with attribute type 2.5.4.22. It wants to know whether 
'teletexTerminalIdentifier' is supported by the server. It happily 
reads the declaration from attributeTypes in sub schema sub entry. 
But the syntax used in the attribute type declaration is not 
supported by the server.

The conclusion by the application MUST be:

=> The attribute type is not supported by this server because the 
client application has to assume that the server does not even 
know how to handle data with syntax 1.3.6.1.4.1.1466.115.121.1.51 
(not to speak of matching).

=> All object classes containing the attribute 
'teletexTerminalIdentifier' are not supported.

If you are referring to non-existing syntaxes you should leave out 
attribute ldapSyntaxes in sub schema sub entry completely. In this 
case an application could assume that the server does not make any 
statements about which syntaxes it supports and reasonable 
defaults could be applied.

 >  Applications should not use
> schema which they don't have any knowledge of, except for
> some definition provided in a subschema.

Can you elaborate on this? Phrases starting with "except for" 
usually opens a big can of worms...

>  Subschema doesn't
> provide the application with knowledge of semantics.

I'm not talking about semantics at all.

Ciao, Michael.