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Re: sub-tree filtering proposals
On Wed, Jun 09, 2004 at 08:42:04AM -0700, Andy Bierman wrote:
> We do not have WG consensus that all devices can support,
> and all applications need, full Xpath. I think we have
> consensus for a limited set of features:
> - select all nodes matching specified attribute or simple content values
> - select a specific instance of an object, in a manner independent
> of any instance naming scheme
> - select specific nodes by name
> - select by any combination of the above
>
> This is the feature set we have been assuming via the subtree filtering
> examples all along. If some people think we need more powerful
> selection criteria as the minimum feature set, then speak up.
> Juergen's Xpath subset seems to be enough to support this feature set.
> I think the subtree filtering supports it as well.
>
> My biggest concern is that we forget that the target platforms
> for NETCONF agent are embedded operating systems within network
> devices, and small devices don't need the same complex features
> that large devices may need.
>
> IMO, we should do the following (yet another proposal :-)
>
> - mandatory-to-implement subtree node selection
> - optional-to-implement "full Xpath 1.0" node selection
> - #xpath capability set if this is supported
So what is "subtree node selection" compared to "subtree filtering"?
I am confused now. Do you refer to your original selection proposal
now?
> 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.
> The advantages of the proposal above are:
> - subtree filtering is easy to implement on agents;
> only XML parser needed, not XML and Xpath parsers
Come on, parsing Xpath expression is really not that complicated. I am
really wondering on which basis you calculate how much you save on
embedded boxes...
> - 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.
In case "subtree expressions" means just expressions of the form
"/foo/bar", then we are back in SNMP stone age where everything
you want to select on has to be part of the name (OID).
> - 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
At the price of creating another totally incompatible beast.
/js
--
Juergen Schoenwaelder International University Bremen
<http://www.eecs.iu-bremen.de/> P.O. Box 750 561, 28725 Bremen, Germany
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