Re: [NGO] external module properties

[Andy Bierman <ietf at andybierman.com>]

Juergen Schoenwaelder wrote:
> On Sat, Apr 26, 2008 at 02:38:52PM -0700, Andy Bierman wrote:
>> Juergen Schoenwaelder wrote:
>>> On Sat, Apr 26, 2008 at 11:28:20AM -0700, Andy Bierman wrote:
>>>  
>>>> LAST-UPDATED and REVISION are optional in SMIv2.
>>> This is not correct. The SMIv2 does mandate a LAST-REVISION clause
>>> (see section 5 and 5.1 of RFC 2578).  The IETF guidelines in addition
>>> mandate the presence of REVISION clauses and the LAST-UPDATED clause
>>> becomes redundant when you have REVISION clauses. That is why YANG
>>> only has revision statements.
>> some modules like SNMPv2-TC have no MODULE-IDENTITY section
> 
> The modules SNMPv2-SMI, SNMPv2-TC, SNMPv2-CONF defintion the language
> itself and are not proper MIB modules anyway. And in any case, a
> counter example would not invalidate what is written down in RFC 2578.
>  
>>> The YANG language itself does not mandate the presence of one or more
>>> revision statements. This is consistent with YANG's philosophy of
>>> mandating only those things that are essential for the language to
>>> function and leave other things to guidelines or applicability
>>> definitions.
>> I think the NETMOD philosophy should consider the entire
>> network configuration problem, which includes properties like
>> module version.
> 
> It does. There is a revision statement and all the other stuff needed
> for the entire network configuration problem.
> 
>>> PS: If YANG were to support versioned imports, revision clauses
>>>     would have to be mandatory because without version information,
>>>     a compiler would not be able to resolve imports. Right now,
>>>     compilers can do the right thing without having revision
>>>     statements and hence they are optional.
>> External entities (humans, applications) need to be able to distinguish
>> between multiple versions of the same module.  Why does a YANG module
>> need to include a 'namespace' clause?  Maybe some vendors want to
>> ignore namespaces.  IMO, it should not be optional to provide a version
>> identifier.  This is a separate issue from requiring the version identifier
>> to change under certain conditions.
> 
> Namespace information is needed for parsers to work properly in case
> of identifier clashes. And I am sure the IETF will require that
> revision clauses are present in YANG modules. But this is not a
> technical requirement of the language itself; it is a usage guideline
> requirement. I believe this distinction is worthwhile to make.


no -- the prefix is needed for the language parser.
The namespace URI string isn't used anywhere in YANG.

> 
> /js
> 

Andy


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