On Fri, Jul 31, 2015 at 9:46 AM, Lou Berger <[email protected]> wrote:
> Andy, > > On 07/27/2015 12:58 PM, Andy Bierman wrote: > > Hi, > > > > I don't think a standard for relocating subtrees would be worth it. > > I am not in favor of moving /interfaces or /system to a new location. > > That's not how YANG works. It only allows "obsolete and start over". > > > > I would suggest pursuing solutions that don't cause > > as much disruption and expense as possible. > > > > I think it would be really good to explore other, less "disruptive" > options. > > Perhaps you'd be willing to have a brain storming session off-line? (Of > course, any proposed changes/approaches would be brought to the WG for > normal WG processing.) > > OK -- send an email invite to the meeting. > Lou > > Andy > > For example, a resource directory of symlinks > > (YANG leaf, type instance-identifier) would allow > > standard or vendor modules to be supported. > > The exact location of the data nodes can change over time, > > and be different on each server. > > > > > > Andy > > > > On Mon, Jul 27, 2015 at 8:48 AM, Lou Berger <[email protected] > > <mailto:[email protected]>> wrote: > > > > Andy, > > > > Thanks for the good information. (I'll followup off line a bit if > > that's okay.) Of course there's a small matter of getting something > > standardized. > > > > Lou > > > > On July 27, 2015 2:19:09 AM Andy Bierman <[email protected] > > <mailto:[email protected]>> wrote: > > > >> > >> > >> On Sun, Jul 26, 2015 at 5:31 PM, Lou Berger <[email protected] > >> <mailto:[email protected]>> wrote: > >> > >> Andy, > >> > >> Have you thought through implications / possibilities for > >> existing models, e.g., interfaces? > >> > >> > >> > >> First we have to define various forms of relocation. > >> > >> (1) Aggregation of datastores > >> > >> The simplest form is aggregation. > >> It is possible to define a YANG container that is a conceptual > >> document root, such that the set of child nodes matches the set > >> of top-level YANG data nodes supported by the server. > >> > >> A YANG extension can mark a YANG container or anyxml as a docroot. > >> Yuma-based code has been doing this for years with a YANG > >> extension called "root" > >> > >> http://www.netconfcentral.org/modules/yuma-ncx/2013-09-23#root.554 > >> > >> http://svn.tools.ietf.org/svn/wg/netmod/yang-1.1/issues.html > >> (See Y34-04) > >> > >> The <config> node below is a document root: > >> > >> container servers { > >> list server { > >> key addr; > >> leaf addr { type inet:ip-address; } > >> anydata config { > >> ncx:root; > >> } > >> } > >> } > >> > >> XPath evaluation requires certain inputs, including a context node > >> and a document root. The 'root' extension tells the tool to use > >> the node with the 'root' tag as the document root, when processing > >> XPath within its descendant nodes. Without the tag, the XPath parser > >> would use 'servers' as the document root, which is incorrect for > >> the relocated YANG nodes within 'config'. > >> > >> (2) Move a subtree within the datastore > >> > >> This is the hardest (of course) because it involves moving the > >> context node > >> not the document root. It is possible for tools to get fooled > >> about the intent > >> of the XPath writer. Basically the tool has to remember the > >> original context node, > >> and do some complicated data manipulation, processing [4] Step > >> in XPath 1.0. Multiple relocated subtrees gets even more > complicated. > >> > >> It may be possible to come up with some guidelines on XPath to > avoid. > >> Basically any Xpath that selects nodes by specific names can be > >> relocated automatically. Nodes selected by function, wildcard, > >> axis, etc. > >> will not be so easy. > >> > >> > >> > >> > >> Thanks, > >> Lou > >> > >> > >> > >> Andy > >> > >> > >> On July 26, 2015 4:41:32 PM Andy Bierman <[email protected] > >> <mailto:[email protected]>> wrote: > >> > >>> Hi Acee, > >>> > >>> I agree that "Relocatable YANG" would be very useful, and > >>> have been > >>> thinking about the problem for awhile. I think the key is to > >>> precisely > >>> define a protocol-independent document root for each of the > >>> various > >>> YANG XPath contexts. In most cases the expression can be > >>> automatically relocated to an ancestor root. For the rest, a > >>> YANG mechanism is needed to tell the compiler to force > evaluation > >>> on the old docroot (not the new docroot ancestor). > >>> > >>> > >>> Andy > >>> > >>> > >>> On Sun, Jul 26, 2015 at 10:49 AM, Acee Lindem (acee) > >>> <[email protected] <mailto:[email protected]>> wrote: > >>> > >>> I think being able to place a given model anywhere in the > >>> device tree > >>> would be useful and this would allow a model to be rooted > >>> in different > >>> locations on different devices. Similarly, we’d need the > >>> ability to prefix > >>> XPATH references to data nodes in the model with the root. > >>> Thanks, > >>> Acee > >>> > >>> On 7/20/15, 11:00 PM, "netmod on behalf of Juergen > >>> Schoenwaelder" > >>> <[email protected] <mailto:[email protected]> > >>> on behalf of > >>> [email protected] > >>> <mailto:[email protected]>> wrote: > >>> > >>> >Lada, > >>> > > >>> >Y34 is closed and I have not seen any new argument here > >>> that indicates > >>> >we made a major mistake with the resolution of Y34. As > >>> such, Y34 > >>> >remains closed. > >>> > > >>> >If you want to discuss new ideas to relocate or > >>> "symlink" data models, > >>> >please do so in a separate thread. (And no, we do not > >>> accept new > >>> >issues for YANG 1.1 either at this point in time.) > >>> > > >>> >/js > >>> > > >>> >On Mon, Jul 20, 2015 at 07:42:49PM +0200, Ladislav > >>> Lhotka wrote: > >>> >> > >>> >> > On 20 Jul 2015, at 19:29, Andy Bierman > >>> <[email protected] <mailto:[email protected]>> wrote: > >>> >> > > >>> >> > > >>> >> > > >>> >> > On Mon, Jul 20, 2015 at 10:15 AM, Ladislav Lhotka > >>> <[email protected] <mailto:[email protected]>> > >>> >>wrote: > >>> >> > > >>> >> > > On 20 Jul 2015, at 17:00, Andy Bierman > >>> <[email protected] <mailto:[email protected]>> wrote: > >>> >> > > > >>> >> > > > >>> >> > > > >>> >> > > On Mon, Jul 20, 2015 at 6:08 AM, Ladislav Lhotka > >>> <[email protected] <mailto:[email protected]>> > >>> >>wrote: > >>> >> > > > >>> >> > > > On 20 Jul 2015, at 14:55, Andy Bierman > >>> <[email protected] <mailto:[email protected]>> wrote: > >>> >> > > > > >>> >> > > > Hi, > >>> >> > > > > >>> >> > > > Can you explain why we need 2 broken anyxmls? > >>> >> > > > (The original and a synonym?) The whole point of > >>> >> > > > anydata is that it does not have XML cruft in it. > >>> >> > > > >>> >> > > Yes, I understand this was your main priority. For > >>> implementors > >>> >>using off-the-shelf XML parsers and tools the XML cruft > >>> is not an issue > >>> >>at all. > >>> >> > > > >>> >> > > > >>> >> > > yes it is an issue. > >>> >> > > We need something to model a container full of > >>> arbitrary YANG data > >>> >>nodes. > >>> >> > > This is something that can be applied to the > >>> contents of a > >>> >>datastore. > >>> >> > > >>> >> > anyxml can do that, too. > >>> >> > > >>> >> > > >>> >> > the WG already decided it can't. > >>> >> > The extra XML PIs, etc. are not accepted by all > >>> servers, remember? > >>> >> > There is no use for the extra stuff in the datastore. > >>> >> > I don't see why we need 2 anyxml constructs that > >>> are not > >>> >> > supported by the industry. One is already too many. > >>> >> > >>> >> I agree, but this is what we are going to have. My > >>> proposal was to have > >>> >>just one with two different names. > >>> >> > >>> >> > > >>> >> > > >>> >> > > > >>> >> > > > >>> >> > > Anyway, I believe there are use cases for > >>> arbitrary XML/JSON/CBOR/… > >>> >>with no (YANG) schema available. My only complaint to > >>> “anyxml” has > >>> >>always been that it is a misnomer for encodings other > >>> than XML. > >>> >> > > > >>> >> > > The message encoding on the wire is not the same > issue > >>> >> > > as the contents of a datastore. Our server stores > >>> its own > >>> >> > > internal data structures. XML, JSON, CBOR are > >>> just message > >>> >> > > encoding formats between client and server. The > >>> datastore > >>> >> > > is not encoded in any of these formats. > >>> >> > > >>> >> > The payload of anyxml needn’t directly map to a data > >>> subtree in the > >>> >>usual sense. > >>> >> > > >>> >> > that's precisely the difference between anyxml and > >>> anydata. > >>> >> > The anydata node MUST map directly into data subtrees. > >>> >> > >>> >> If the server doesn’t know the YANG data model at run > >>> time (which is > >>> >>possible) then it cannot do it - for instance, it > >>> cannot properly map > >>> >>module names to namespace URI or handle lists. > >>> >> > >>> >> > > >>> >> > > >>> >> > > >>> >> > > > >>> >> > > > >>> >> > > > >>> >> > > > >>> >> > > > >>> >> > > > > >>> >> > > > I also don't get the value of a single top-level > >>> node called > >>> >>'device' > >>> >> > > > that every YANG model on the planet is supposed > >>> to augment. > >>> >> > > > Can you explain why a protocol operation to > >>> retrieve the > >>> >> > > > document root (/) is not sufficient for the > >>> top-level node? > >>> >> > > > >>> >> > > I don’t intend to defend their model, the more > >>> serious problem IMO > >>> >>is that a model for a single device/function may be > >>> needed in another > >>> >>device that hosts many virtualised devices/functions of > >>> the former type. > >>> >>We don’t have a good solution for this rather typical > >>> situation. > >>> >> > > > >>> >> > > But a single container called "whatever" provides > >>> no such > >>> >>aggregation. > >>> >> > > You would need a list for that. And the NMS might > >>> have multiple > >>> >> > > layers of hierarchy to represent various > >>> aggregations. The NP > >>> >> > > container called "device" is not helpful for > >>> aggregation. > >>> >> > > >>> >> > The parent node can be a list as well. The “root” > >>> node would be like > >>> >>a mount point in a Unix filesystem. > >>> >> > > >>> >> > > >>> >> > Are you saying all data on a device needs to be in a > >>> top-level list > >>> >>called 'device' > >>> >> > because an NMS might exist that wants to have the > >>> datastores from > >>> >>lots of devices? > >>> >> > As Martin pointed out several times, the NMS can > >>> make its own > >>> >>container or > >>> >> > lists. It does not need the device to mirror its > >>> own structure. > >>> >> > >>> >> As I said, I don’t care that much about the “device” > >>> container. What > >>> >>would be really useful is to have the possibility to do > >>> e.g. this: > >>> >> > >>> >> virtual-node* [name] > >>> >> name > >>> >> if:interfaces > >>> >> ... > >>> >> > >>> >> to support the use case where all virtual nodes are > >>> managed by the same > >>> >>NETCONF/RESTCONF server. > >>> >> > >>> >> Lada > >>> >> > >>> >> > > >>> >> > > >>> >> > > >>> >> > Lada > >>> >> > > >>> >> > Andy > >>> >> > > >>> >> > > >>> >> > > > >>> >> > > > >>> >> > > > >>> >> > > Lada > >>> >> > > > >>> >> > > > >>> >> > > Andy > >>> >> > > > >>> >> > > > >>> >> > > > > >>> >> > > > Andy > >>> >> > > > > >>> >> > > > > >>> >> > > > > >>> >> > > > On Mon, Jul 20, 2015 at 5:48 AM, Ladislav Lhotka > >>> <[email protected] <mailto:[email protected]>> > >>> >>wrote: > >>> >> > > > > >>> >> > > > > On 20 Jul 2015, at 14:45, Ladislav Lhotka > >>> <[email protected] <mailto:[email protected]>> wrote: > >>> >> > > > > > >>> >> > > > > Hi, > >>> >> > > > > > >>> >> > > > > after listening to the presentation of > >>> >> > > > > draft-rtgyangdt-rtgwg-device-model-00 at RTGWG > >>> session, I am > >>> >>wondering > >>> >> > > > > whether the solution chosen for Y34 is really > >>> useful. > >>> >> > > > > > >>> >> > > > > The draft states they want to reuse > >>> ietf-interfaces but their > >>> >>tree in > >>> >> > > > > fact is > >>> >> > > > > > >>> >> > > > > +--rw device > >>> >> > > > > +--rw info > >>> >> > > > > | +--rw device-type? enumeration > >>> >> > > > > +--rw hardware > >>> >> > > > > +--rw interfaces > >>> >> > > > > | +--rw interface* [name] > >>> >> > > > > | ... > >>> >> > > > > +--rw qos > >>> >> > > > > > >>> >> > > > > So the "interfaces" container is no more a > >>> top-level node. > >>> >>There are > >>> >> > > > > three possible options: > >>> >> > > > > > >>> >> > > > > 1. Change the ietf-interfaces module. > >>> >> > > > > 2. Replicate its contents in another module. > >>> >> > > > > 3. Extend YANG so that a *specific* schema > >>> tree can be grafted > >>> >>at a > >>> >> > > > > given data node. > >>> >> > > > > > >>> >> > > > > IMO #1 & #2 are really bad. I thought Y34-04 > >>> was essentially #3 > >>> >>but it > >>> >> > > > > seems it is not so because it doesn't specify > >>> a concrete data > >>> >>model > >>> >> > > > > that's allowed at a given location. > >>> >> > > > > > >>> >> > > > > On the other hand, the only real contribution > >>> of "anydata" over > >>> >>"anyxml" > >>> >> > > > > is that is doesn't permit mixed content in > >>> XML, which is IMO > >>> >>not much. > >>> >> > > > > > >>> >> > > > > I know Y34 was already closed but I think it > >>> is more important > >>> >>to do > >>> >> > > > > things right before YANG 1.1 becomes an RFC. > >>> >> > > > > > >>> >> > > > > What I want to propose is this: > >>> >> > > > > > >>> >> > > > > - Rename "anydata" as a synonym to "anyxml", > >>> and deprecate > >>> >>"anyxml" (but > >>> >> > > > > keep it for backward compatibility). > >>> >> > > > > >>> >> > > > s/Rename/Introduce/ > >>> >> > > > > >>> >> > > > > > >>> >> > > > > - Introduce a new statement and data node > >>> type, e.g. "root", > >>> >>that will > >>> >> > > > > extend the schema tree starting from that > >>> data node with a > >>> >>precisely > >>> >> > > > > specified data model. The specification can > >>> be same or similar > >>> >>as > >>> >> > > > > in yang-library. > >>> >> > > > > > >>> >> > > > > I believe there are other use cases in the > >>> existing modules. For > >>> >> > > > > example, the ietf-routing module could simply > >>> define the data > >>> >>model for > >>> >> > > > > a single routing instance (i.e. without > >>> "routing-instance" list > >>> >>at the > >>> >> > > > > top), and it can be then used without changes > >>> on simple > >>> >>devices, and > >>> >> > > > > more complex router implementations can graft > >>> it as a subtree > >>> >>under > >>> >> > > > > "routing-instance", "networking-instance" or > >>> whatever. > >>> >> > > > > > >>> >> > > > > Lada > >>> >> > > > > > >>> >> > > > > -- > >>> >> > > > > Ladislav Lhotka, CZ.NIC Labs > >>> >> > > > > PGP Key ID: E74E8C0C > >>> >> > > > > > >>> >> > > > > _______________________________________________ > >>> >> > > > > netmod mailing list > >>> >> > > > > [email protected] <mailto:[email protected]> > >>> >> > > > > https://www.ietf.org/mailman/listinfo/netmod > >>> >> > > > > >>> >> > > > -- > >>> >> > > > Ladislav Lhotka, CZ.NIC Labs > >>> >> > > > PGP Key ID: E74E8C0C > >>> >> > > > > >>> >> > > > > >>> >> > > > > >>> >> > > > > >>> >> > > > _______________________________________________ > >>> >> > > > netmod mailing list > >>> >> > > > [email protected] <mailto:[email protected]> > >>> >> > > > https://www.ietf.org/mailman/listinfo/netmod > >>> >> > > > > >>> >> > > > >>> >> > > -- > >>> >> > > Ladislav Lhotka, CZ.NIC Labs > >>> >> > > PGP Key ID: E74E8C0C > >>> >> > > > >>> >> > > > >>> >> > > > >>> >> > > > >>> >> > > > >>> >> > > >>> >> > -- > >>> >> > Ladislav Lhotka, CZ.NIC Labs > >>> >> > PGP Key ID: E74E8C0C > >>> >> > > >>> >> > > >>> >> > > >>> >> > > >>> >> > _______________________________________________ > >>> >> > netmod mailing list > >>> >> > [email protected] <mailto:[email protected]> > >>> >> > https://www.ietf.org/mailman/listinfo/netmod > >>> >> > >>> >> -- > >>> >> Ladislav Lhotka, CZ.NIC Labs > >>> >> PGP Key ID: E74E8C0C > >>> >> > >>> >> > >>> >> > >>> >> > >>> >> _______________________________________________ > >>> >> netmod mailing list > >>> >> [email protected] <mailto:[email protected]> > >>> >> https://www.ietf.org/mailman/listinfo/netmod > >>> > > >>> >-- > >>> >Juergen Schoenwaelder Jacobs University Bremen > >>> gGmbH > >>> >Phone: +49 421 200 3587 Campus Ring 1 | 28759 > >>> Bremen | Germany > >>> >Fax: +49 421 200 3103 > >>> <http://www.jacobs-university.de/> > >>> > > >>> >_______________________________________________ > >>> >netmod mailing list > >>> >[email protected] <mailto:[email protected]> > >>> >https://www.ietf.org/mailman/listinfo/netmod > >>> > >>> _______________________________________________ > >>> netmod mailing list > >>> [email protected] <mailto:[email protected]> > >>> https://www.ietf.org/mailman/listinfo/netmod > >>> > >>> > >>> _______________________________________________ > >>> netmod mailing list > >>> [email protected] <mailto:netmod%40ietf.org> > >>> https://www.ietf.org/mailman/listinfo/netmod > >>> > >> > > > >
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