Hi,
On Thu, Sep 26, 2019 at 9:14 AM tom petch <[email protected]> wrote: > Inline > > Tom Petch > > ----- Original Message ----- > From: "Andy Bierman" <[email protected]> > To: "Rob Wilton (rwilton)" <[email protected]> > Cc: <[email protected]>; <[email protected]> > Sent: Thursday, September 26, 2019 3:33 PM > > On Thu, Sep 26, 2019 at 3:32 AM Rob Wilton (rwilton) <[email protected]> > wrote: > > > > > > > > -----Original Message----- > > > From: netmod <[email protected]> On Behalf Of Martin Bjorklund > > > Sent: 26 September 2019 08:45 > > > To: [email protected] > > > Cc: [email protected]; [email protected] > > > Subject: Re: [netmod] 答复: 答复: Please clarify implementation about > > > ‘when’ > > > > > > > > > > > > > It also says in 8.2: > > > > > > > > > > o If a request modifies a configuration data node such that > any > > > > > node's "when" expression becomes false, then the node in > the > > > data > > > > > tree with the "when" expression is deleted by the server. > > > > > > > > Right. But the request won't modify a configuration data node > because > > > > it is rejected. So the premise of the above implication doesn't > hold, > > > > and the conclusion doesn't apply. > > > > > > With the same logic you can claim conformance if you reject a > request to > > > create nodes under a case if another case is active. I think it is > quite > > > clear that this auto-deletion is part of the spec, and something > clients > > > can rely on. If the intention had been that this was optional to > > > implement, it would have been clearly stated, and there would have > been > > > mechanism present for clients to detect this. > > > > > I don't like the 'when' behaviour, I would have rather that clients > were > > forced to delete the configuration explicitly (or pass an option for > an > > implicit delete). > > I hear the opposite from customers. > They insist that the server implement every last detail of the > machine-readable YANG, > especially when-stmt auto-deletion. The auto-cleanup is seen as a > feature. > > > However, I do agree with Martin & Juergen, that the intent of the spec > is > > that servers perform the 'when' auto-delete behaviour, and clients > must be > > able to rely on compliant servers behaving this way. > > > > agreed. > It is hard to argue against consistent, predicable server behavior > for datastore editing. (NP containers and NMDA are also causing > problems, > and should be fixed in yang-next if that ever happens). > > <tp> > > Andy > > This caught my eye. What is the problem with NMDA? Anything specific? > > My own problem is that it is different to what has been proposed as > suitable for the previous 12 years but I doubt if many customers would > think that. > > My comments are in the context of operator expectations for consistent implementations. The first problem with NMDA is the new YANG library. There is an assumption that the client can and will change from an architecture where there is 1 schema tree per server to an architecture where there can be a completely different schema tree for configuration vs operational datastores. There is no such desire or willingness on the client side to properly address this complexity. IMO NMDA is going to need to function without this complexity. The benefits of <operational> are not hindered at all (in a properly implemented server) if /yang-library is left out. The IETF has completely punted the problem of converting data for a configuration datastore to the schema tree for <operational>. Deviations may be different. A leaf may be string in 1 tree and decimal64 in the other. There is an incorrect assumption that software developers will deal with these corner-cases (correctly and consistently). The other big problem is an untested NMDA transition strategy that is not well understood by vendors. Should non-NMDA (/foo-state) be visible to <get-data> or just <get>? Using the YANG library to separate the modules relies on the assumption that the client is capable of managing each datastore independently (instead of 1 schema tree per server). > Tom Petch > > Andy > Thanks, > > Rob > > > > > > Andy > > > > > > > > > > /martin > > > _______________________________________________ > > > netmod mailing list > > > [email protected] > > > https://www.ietf.org/mailman/listinfo/netmod > > _______________________________________________ > >
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