Hi Stuart, Thanks for the thoughts. More in-line...
> From: STUART VENTERS. March 16, 2016 3:49 PM > > Eric, > > I did the suggested OpenDaylight (ODL)search, and yes there is a lot of > activity > there. There are a lot of trees in that forest. > > The best overview I found seems to be here. > https://wiki.opendaylight.org/view/OpenDaylight_Controller:_SAL_Architecture > _Overview#Nested_Subsystems > > Mapping my words to ODL, > My Sibling is the ODL Nested system. > My Parent might be ODL Top-level Subsystem? > > Having had lunch to think about it, I don't think I should have picked > NetConf as > a place to choose what data to mount. > I suspect it should be somewhere in the application, separate for both Yang > and > Netconf. > ODL appears to use the Northbound Restconf interface to do this function > <module xmlns="urn:opendaylight:params:xml:ns:yang:controller:config"> > > Stepping back, for this mounting stuff, there are at least 3 issues: > 1) Specifying a where in the Parent schema to put the sibling schema. > 2) Specifying the type of the sibling. > 3) Specifying what sibling data instance to put at a specific parent node data > instance. > > I think Yang would be a great place to do 1 and 2, but I think the > application > should handle 3. > ODL appears to put 1) in Yang, I'm not sure about 2), and 3) in the > application. > Your proposed definition's mention of data-tree appears to put 3 into Yang > with > appears to conflict with ODL. ODL Mounts instance data. One example showing how applications can get to that can be seen at: http://sdntutorials.com/how-to-access-data-in-md-sal-from-mount-point/ > Since you clearly don't want however Yang turns out to collide with ODL, but > appear to be proposing something that collides, I must not understand? I don't see the collision of (3) with the originally proposed definition for "Peer Mount". It might be worth looking at: https://tools.ietf.org/html/draft-clemm-netmod-mount-03 which was used an initial seed for ODL's implementation of Peer Mount. > Another use case: > ODL Yang device mounting is about grafting and removing whole, existing > devices as branches in a single tree on a running system. Grafting, yes. Not sure about removing as the Mount is a reference, not an actual relocation. > For this, there may be some benefit in treating the grafted branch as a > special > sort of node in the tree. > Having a special keyword like 'mount' might help this, or the application > function > that does 3) above could handle it. There certainly are trade-offs between application-centric data representation and infrastructure-centric representation. Open Daylight is a good test-case here as it provides network-wide abstractions to a diverse application set. (I.e., the end-goal of Peer Mount always has been simplifying life for the application developer, and these network-wide abstractions are intended for this purpose.) > Another use case is simply making a big device model by grafting together > smaller, whole, existing models. > In this case, the benefit may be to make the grafted branch look like a non- > special vanilla node in the tree. > In this case, I don't see the benefit over a special keyword like 'mount' > over an > existing one like 'uses'. Peer Mount and Alias Mount are intended to enable the referencing of existing, populated data trees. Eric > Regards, > > Stuart > > > -----Original Message----- > From: Eric Voit (evoit) [mailto:ev...@cisco.com] > Sent: Wednesday, March 16, 2016 12:20 PM > To: STUART VENTERS > Cc: netmod@ietf.org; Martin Bjorklund (mbjorklu); 'Juergen Schoenwaelder' > Subject: RE: [netmod] Differentiating the types of Mount > > > From: STUART VENTERS, March 16, 2016 12:58 PM > > > > Defining a schema-tree seems Yang's strong suite. > > I'm not sure if the suite extends to defining what goes into a > > data-tree governed by the schema-tree. > > Hi Stuart, > > Open Daylight has found Mounting YANG data from one device to another has > proven central to their effort. Doing a quick Google search for "mount > site:opendaylight.org" gives 800+ results. > > Based on that, I was hoping that being defining the variants of Mount across > different constituencies would help us not collide as the technologies evolve. > This includes a shared definition of "YANG Mount" which shows what is common > across all efforts. > > Thanks, > Eric > > > Perhaps: > > > > YANG Mount > > ---------------- > > Definition: An abstracted term for a YANG mechanism that grafts a > > sibling schema-tree as a subtree of a parent schema-tree. > > Purpose: Provides flexibility by enabling the growth of YANG models > > via an explicit reference to other YANG models defined elsewhere. > > > > Given the ability to specify a combined schema-tree, maybe something > > at the protocol level could specify what data to use to populate the grafted > tree. > > This could provide a place to specify details like who has ownership > > of the data, if it is RW, etc. > > > > NETCONF Mount > > ------------------ > > Definition: An abstracted term for a NETCONF mechanism to construct a > > combined data-tree according to a schema defined with YANG mount. > > Purpose: ... > > > > > > > > -----Original Message----- > > From: netmod [mailto:netmod-boun...@ietf.org] On Behalf Of Juergen > > Schoenwaelder > > Sent: Wednesday, March 16, 2016 6:23 AM > > To: Eric Voit (evoit) > > Cc: netmod@ietf.org; Martin Bjorklund (mbjorklu) > > Subject: Re: [netmod] Differentiating the types of Mount > > > > On Wed, Mar 16, 2016 at 03:59:50AM +0000, Eric Voit (evoit) wrote: > > > To help differentiate between concepts and drafts, below are > > > strawman > > definitions for the various types of Mount which we have been discussing > > over > > the last year in Netmod. Thoughts/suggestions? > > > > > > YANG Mount > > > ---------------- > > > Definition: An abstracted term for a mechanism that a parent YANG > > > model can > > use to link in YANG information defined or located elsewhere. > > > Purpose: Provides model flexibility by enabling the growth of YANG > > > trees via > > an explicit reference to other YANG information and structures. > > > > Trying to rewrite the definition to be more consistent with existing > > terminology: > > > > The abstract concept of incorporating a YANG-defined data tree (the > > mounted data tree) into a existing YANG-defined data tree (the > > parent data tree). > > > > Well, this is not really correct, perhaps we have to just say 'tree' > > instead of 'data tree' since a schema mount (as I understand it) seems > > to incorporate a schema tree into another schema tree while the other > > two mounts incorporate a data tree into a data tree. So perhaps the > > general definition is something like this: > > > > The abstract concept of incorporating a YANG-defined data tree or > > schema tree (the mounted data or schema tree) into a existing > > YANG-defined data tree or schema tree (the parent data tree). > > > > The schema mount then essentially removes data tree and the other two > > mounts remove the schema tree from this definition. > > > > Is your alias mount simply a special case of a peer mount where the > > peer is local? Or is there more to it? In other words, would it be > > reasonable to think of the terms in this way: > > > > +-> schema (tree) mount > > | > > mount -> | +-> local data tree (alias) mount > > +-> data (tree) mount -> | > > +-> remote data tree (peer) mount > > > > /js > > > > -- > > 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 > > netmod@ietf.org > > https://www.ietf.org/mailman/listinfo/netmod _______________________________________________ netmod mailing list netmod@ietf.org https://www.ietf.org/mailman/listinfo/netmod
