Re: FW: I-D ACTION:draft-weijing-netconf-interface-00.txt

[Andy Bierman <abierman@cisco.com>]

At 08:32 AM 7/9/2003, Juergen Schoenwaelder wrote:

>>>>>> Allen, Keith writes:
>
>Keith> What is your feeling here?  When both the CMIP and SNMP folks
>Keith> decided that the ASN.1 data definition language alone was not
>Keith> enough, they each developed their own object definition
>Keith> language of sorts.  I have heard that the CMIP folks debated
>Keith> quite a bit over the need to support the ability to define and
>Keith> invoke methods on objects but ended up supporting the ability
>Keith> with the M-Action capability.  I don't know if the SNMP folks
>Keith> debated it but they didn't end up supporting a way to define
>Keith> and invoke methods on objects.  
>
>SNMP folks did not even manage to define create/delete - we just
>have this RowStatus hack which pushes some of the complexity from
>the protocol into the instrumentation, which has proven to be
>problematic. :-(
>
>Keith> If you look at CMIP information models, there are surprisingly
>Keith> few custom methods defined for the objects.  And some of the
>Keith> more often used methods, such as setting up a connection, could
>Keith> have just as easily been done with a standard "create" method.
>
>Some methods (or RPC calls if you will) have proven to be very
>useful. The most prominent example is running a traceroute or ping
>from a remote device. Doing these things without protocol support to
>invoke operations (a term I prefer instead of methods since it has
>less OO baggage) results in kind of ugly solutions. Look at RFC 2925
>for an example. In other words, many things can be done very well
>without such a "method" capability but some things are really hard to
>do without such a capability. It is a trade-off, as usual.

The xmlconf draft describes user-defined rpc calls,
which are the same as 'exec' commands on some routers.
Is this what you mean or something else?


>Keith> I lean towards using standard create, delete, get, set only,
>Keith> mainly because I think trying to devise a way of defining
>Keith> methods on objects in XML schema will be too painful and not
>Keith> worth the complexity.  I know this is not truly
>Keith> object-oriented, but I think it is reasonable given that the
>Keith> answer is XML.  I do support, however, trying to view the
>Keith> elements in an XML infoset as object as much as possible.
>
>I think the logic is wrong. We have to figure out whether we need
>methods (and whether we need them now or prefer a plan to do them
>later) and then we select/create a suitable language that supports
>this, if needed. Not the other way round.

Do you mean methods in the OO sense -- RPC-like exchanges
which can be specific to a particular data object?  (Rather
than a fixed set of high-level methods which are potentially
applicable to all data objects).

>BTW, WSDL is in my understanding a way to define methods (well,
>actually just RPCs since there is no notion of an object binding if I
>recall right - and they are not even necessarily RPCs - just messages)
>where the data structures exchanged are defined by XML schemas.  Since
>people seem to hate SOAP, we would need something similar to WSDL to
>define methods for netconf if we were to support "methods" in the
>netconf protocol.
>
>/js

Andy



>-- 
>Juergen Schoenwaelder               International University Bremen
><http://www.eecs.iu-bremen.de/>     P.O. Box 750 561, 28725 Bremen, Germany
>
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