RE: sub-tree filtering proposals

[Andy Bierman <abierman@cisco.com>]

At 09:31 AM 6/9/2004, Glenn Waters wrote:

>> From: Andy Bierman [<mailto:abierman@cisco.com>mailto:abierman@cisco.com] 
>> Sent: Wednesday, June 09, 2004 11:42 
>> To: Frank Strauß 
>> Cc: netconf@ops.ietf.org 
>> Subject: Re: sub-tree filtering proposals 
>  
>> IMO, we should do the following (yet another proposal :-) 
>> 
>>   - mandatory-to-implement subtree node selection 
>
>Is the mandatory to implement based on what Jeurgen proposed? 

this is the subtree filtering already in the draft and
documented in my original email on this thread.  This
is not partial Xpath


>>   - optional-to-implement "full Xpath 1.0" node selection 
>>     - #xpath capability set if this is supported 
>> 
>> The XML Directorate consensus seems to be leaning to partial 
>> Xpath, but there are strong concerns that an Xpath subset will be 
>> incompatible with standard tools, and therefore pointless. 
>
>It's not pointless. Some reasons that an XPath subset is useful are: 
>- compatability with full XPath which allows developers to learn one set of filtering 
>- code reuse between subset and full implementation 
>- training will be easier -- can leverage existing training for the bits we support 
>- a clean migration path from "XPath-lite" to "XPath-full" 

I think the WG is still split on this point.
I agree with Phil.  We will have a lot of variance
between minimal subset and full Xpath, and application
writers will have difficulty managing this variance.
If we had mandatory subtree plus optional full Xpath,
there is less variance possible (just 2 choices: full 
subtree, full Xpath).

Or we could make both filtering mechanisms optional and
let the market decide which ones are useful.  


>> 
>> The advantages of the proposal above are: 
>>   - subtree filtering is easy to implement on agents; 
>>     only XML parser needed, not XML and Xpath parsers 
>>   - subtree expressions are valid XML which look identical 
>>     to the data models (XML content) that operators will 
>>     need to know anyways.  Xpath should not be mandatory-to-know 
>>     in order to use NETCONF. 
>>   - Vendors are encouraged to also support full Xpath 1.0, if it 
>>     is appropriate for the platform and data model size 
>>   - We avoid definition and deployment of a NETCONF-only Xpath subset 
>> 
>> Andy 
>
>Regards, /gww 

Andy


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