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Re: roots wasRe: filtering problem

Hello,
I think a filter that works on the content of the notification (as it would be sent) is needed. People usually filter on things like severity or eventType. E.g. severity is not even part of the data model. 

I think the filter should work on the notification content.

Balazs

Andy Bierman wrote:

tom.petch wrote:

----- Original Message -----
From: "Balazs Lengyel" <balazs.lengyel@ericsson.com>
To: "tom.petch" <cfinss@dial.pipex.com>
Cc: <ietf@andybierman.com>; <netconf@ops.ietf.org>
Sent: Thursday, July 19, 2007 5:14 PM
Subject: Re: roots wasRe: filtering problem



Hello,
I think the datastore will often have multiple roots. I foresee/have heard of 
the following

situations that as I understand are all valid in Netconf:
1) One root in one namespace, other namespaces might be mounted as subtrees 
2) One root per namespace
3) One namespace but with many root elements
4) Many roots in many namespaces
Case 2 can be viewed as a the single rooted case 1) where the first branching 
is according to

the namespace.

Case 3) and 4) I feel the filter should be applied to each root and the

results of these

combined under the <data> element in the get/get-config reply.

Comments?
Mmmm - even more complex than I thought. My initial concern was whether or not the Notifications, the draft in Last Call, were regarded for filtering purposes as part of the configuration datastore at all, or whether the filter was applied 
to the document as it would appear on the wire were it to pass a filter.




This is the $64 question.
When a <filter> element is provided in the <create-subscription>,
does it apply to the conceptual (internal) NETCONF database,
or rather an XML instance document representing the database?  (no)

The examples seem to contradict text that says it works like <get>.
They show the filter is for the <notification> contents,
starting at its one and only child node -- e.g., <event>.

The draft needs to specify the data root for the notification <filter>.


Tom Petch


Balazs


Andy



tom.petch wrote:

This may relate to something that has been bugging me.
XPath is - at times - specified in terms of a root, and an XML document has 
a

single root element.  What is on the wire is an XML document but the

datastore

is not - as Andy has pointed out before.
So what is an XPath filter being applied to? The event as it would appear 
on
the wire as an XML document? A conceptual document created in the datastore 
for

the purposes of filtering?  And if the latter, should we - we should! -

specify

a root, either for the purposes of the examples or else for everything.
RFC4741 is quite discursive about roots but the notification I-D is silent; 
I

think that this last needs to change.

Tom Petch

----- Original Message -----
From: "Martin Bjorklund" <mbj@tail-f.com>
To: <ietf@andybierman.com>
Cc: <netconf@ops.ietf.org>
Sent: Friday, July 13, 2007 4:43 PM
Subject: Re: filtering problem



Andy Bierman <ietf@andybierman.com> wrote:

Hi,
There is another problem with filtering and the examples in sec 5: (!!!) 

The draft must say exactly where in the <notification> element
that the <filter> is applied. The current text does not say anything. 
Agreed.


All the examples in sec. 5 are broken because the 'notification type'
layer is missing.

I think it is ok.  Specify that the filter is applied to the
'notificationContent' element as root (which is the abstract element).


The examples assume the filters can only be
applied to a conceptual datastore, just like the <rpc> filter.

However, the most commonly needed filter is going to be
on the notification type itself!

Example (w/o namespaces):

   <notification>
     <configChange>
        <configChangeTime>date-time string...</configChangeTime>
        <configChangedBy>fred@example.com</configChangedBy>
<configTarget>/interfaces/interface[name='eth0']</configTarget> 
         ...
     </configChange>
   </notification>

For simplicity, assume the manager just wants
this one notification type. The filter is going to be something like:

  <filter type="subtree">
    <configChange/>
  </filter>

Yes, and IMO this is consistent with the examples.


/martin




A filter for configChange just on a specific configTarget might be:

  <filter type="subtree">
    <configChange>
      <configTarget>/interfaces/interface[name='eth0']</configTarget>
    </configChange>
  </filter>

The way the draft is now does not reflect how notifications are
actually structured.


Andy




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--
Balazs Lengyel                       Ericsson Hungary Ltd.
TSP System Manager
ECN: 831 7320                        Fax: +36 1 4377792
Tel: +36-1-437-7320     email: Balazs.Lengyel@ericsson.com

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