Hi Rob,
Thanks for your feedback. The base module we’re talking about is an IETF standard module (now called ietf-hardware) and the augmentations have been added by BBF in the context of pre-provisioning of pluggable HW items in a device (there is a mail thread on including the BBF extension to the IETF entity model but this is not concluded yet. Your second alternative would require us to modify the ietf-hardware module and that needs to come from IETF first before we can adopt this. Best regards - Vriendelijke groeten, Bart Bogaert Broadband-Access System Architect Data Contact number +32 3 2408310 (+32 477 673952) NOKIA Copernicuslaan 50, 2018 Antwerp, Belgium Fortis 220-0002334-42 VAT BE 0404 621 642 Register of Legal Entities Antwerp << This message (including any attachments) contains confidential information intended for a specific individual and purpose, and is protected by law. If you are not the intended recipient, you should delete this message. Any disclosure, copying, or distribution of this message, or the taking of any action based on it, is strictly prohibited without the prior consent of its author. >> From: Robert Wilton [mailto:[email protected]] Sent: 29 November 2016 11:47 To: Bogaert, Bart (Nokia - BE) <[email protected]> Cc: [email protected] Subject: Re: [netmod] Mandatory leafs via augment Hi Bart, You have probably already considered this, but an alternative solution would be to use a global flag to predicate a "leaf d" when statement on, e.g. something along the lines of ... module base-class { prefix base; container base { leaf a; leaf b; leaf c; } } module augment-base { prefix aug; import base-class { prefix base; } leaf globalEnableAugmentedBase { type empty; description "Global flag to control whether leaf d is required." } augment '/base:base' { when '/globalEnableAugmentedBase'; leaf d { mandatory true; } } } This is compliant with the rules, in that a client has to be explicitly aware and enable the "leaf d" functionality. Of course there is still an expectation that clients that are not aware of "augment-base" could still configure "base" objects. It still isn't clear to me whether in your case "base-class" is a standard module, and "augment-base" is a vendor augmentation, in which case it is strongly desirable not to force vendor specific mandatory augmentations, since it means that a generic client that only knows about base-class cannot inter-operate with a device that expects augment-base. Conversely, if the base container is expected to represent an abstract base class, with separate concrete instantiations, then adding a mandatory choice statement to your container base, may allow you to express this more cleanly in YANG. E.g. an example for the latter case is: module base-class { namespace "urn:temp:augment"; prefix base; container base { leaf a { type string; } leaf b { type string; } leaf c { type string; } choice subtype { mandatory true; } } } module augment-base { namespace "urn:temp:augment-base"; prefix aug; import base-class { prefix base; } augment '/base:base/base:subtype'{ case d-subclass { container d { leaf d { mandatory true; type string; } } } } } Regards, Rob On 29/11/2016 08:23, Bogaert, Bart (Nokia - BE) wrote: Andy, Thanks for this feedback. The server would indeed advertise this deviation as a “flag” to the client that the server is expecting more than just the base class. Best regards - Vriendelijke groeten, Bart Bogaert Broadband-Access System Architect Data Contact number +32 3 2408310 (+32 477 673952) NOKIA Copernicuslaan 50, 2018 Antwerp, Belgium Fortis 220-0002334-42 VAT BE 0404 621 642 Register of Legal Entities Antwerp << This message (including any attachments) contains confidential information intended for a specific individual and purpose, and is protected by law. If you are not the intended recipient, you should delete this message. Any disclosure, copying, or distribution of this message, or the taking of any action based on it, is strictly prohibited without the prior consent of its author. >> From: Andy Bierman [mailto:[email protected]] Sent: 28 November 2016 18:39 To: Robert Wilton <mailto:[email protected]> <[email protected]> Cc: Bogaert, Bart (Nokia - BE) <mailto:[email protected]> <[email protected]>; [email protected] <mailto:[email protected]> Subject: Re: [netmod] Mandatory leafs via augment On Mon, Nov 28, 2016 at 7:47 AM, Robert Wilton <[email protected] <mailto:[email protected]> > wrote: Hi Bart, Alas, it sounds like you are attempting to do exactly what the existing text is attempting to prevent you from doing. In particular, your approach will break an existing client from working that hasn't been coded to be aware of the new augment-base module. In terms of your solution, unless I'm missing something, then I'm not sure whether the deviation really helps - it seems to be equivalent to be just writing the must statement directly on 'leaf d' in the augment-base module IIRC, I don't think that YANG prevents you from using a "must" statement to effectively make a leaf mandatory. However, even if this is allowed, it is probably against the spirit of the constraint that YANG is attempting to impose here. I.e. specifically that changes/augmentations to YANG modules are expected to be fully backwards compatible. YANG conformance is per module. That means is is OK for a client to code to "base-class" and not the "augment-base" module. I have tried several times to fix that in YANG with conformance statements that can be more than one module, but this has not been seen as important. Robert is correct that the deviation does not change things at all, other than this is the correct way to do things that are not allowed (and your server must advertise the deviation, which tells the world "I do not implement module "base-class" correctly".) 6087bis allows conditionally mandatory, which usually means you pick a new value for something in the base module (e.g, leaf a, b, or c). The old client will not set leaf b to the new value. leaf b { enumeration { // old enums enum new; } } leaf d { when "../b = new"; mandatory true; type string; } Thanks, Rob Andy On 28/11/2016 15:01, Bogaert, Bart (Nokia - BE) wrote: What we want to express is that if the NC client sends a request to configure an object of class base we have a means to express that it also has to send a value for the augmented leaf. The reason why it is in an augment is because we can't modify the base class. Best regards - Vriendelijke groeten, Bart Bogaert Broadband-Access System Architect Data Contact number +32 3 2408310 (+32 477 673952) NOKIA Copernicuslaan 50, 2018 Antwerp, Belgium Fortis 220-0002334-42 VAT BE 0404 621 642 Register of Legal Entities Antwerp << This message (including any attachments) contains confidential information intended for a specific individual and purpose, and is protected by law. If you are not the intended recipient, you should delete this message. Any disclosure, copying, or distribution of this message, or the taking of any action based on it, is strictly prohibited without the prior consent of its author. -----Original Message----- From: Martin Bjorklund [mailto:[email protected] <mailto:[email protected]> ] Sent: 28 November 2016 14:45 To: Bogaert, Bart (Nokia - BE) <[email protected] <mailto:[email protected]> > Cc: [email protected] <mailto:[email protected]> ; [email protected] <mailto:[email protected]> Subject: Re: [netmod] Mandatory leafs via augment "Bogaert, Bart (Nokia - BE)" <[email protected] <mailto:[email protected]> > wrote: Hi Rob, In the case we're trying to work out basically client and server would be aware of base class, augmentation and deviation as the SW running on the box is expecting a value for a leaf of the augmented data, so leaf d for the NC server (and the application SW dealing with the HW) is expected to have a value in the device. The device would not support objects of the base class only. I could understand that a NC client interacts with other servers only supporting the base class as that device may not require the augmented leafs. I don't understand what you want to do. It seems as if you're saying that if the client thinks that leaf d is mandatory then leaf d is mandatory. Otherwise leaf d is not mandatory. /martin Best regards - Vriendelijke groeten, Bart Bogaert Broadband-Access System Architect Data Contact number +32 3 2408310 (+32 477 673952) NOKIA Copernicuslaan 50, 2018 Antwerp, Belgium Fortis 220-0002334-42 VAT BE 0404 621 642 Register of Legal Entities Antwerp << This message (including any attachments) contains confidential information intended for a specific individual and purpose, and is protected by law. If you are not the intended recipient, you should delete this message. Any disclosure, copying, or distribution of this message, or the taking of any action based on it, is strictly prohibited without the prior consent of its author. From: Robert Wilton [mailto:[email protected] <mailto:[email protected]> ] Sent: 28 November 2016 12:48 To: Bogaert, Bart (Nokia - BE) <[email protected] <mailto:[email protected]> > Cc: [email protected] <mailto:[email protected]> Subject: Re: [netmod] Mandatory leafs via augment Hi Bart, In your idea, am I correct to assume that only the client loads (base-class, augment-base, and base-deviation), and the server only knows about (base-class and augment-base)? Further, am I right to assume that the server would still support clients configuring base even if they don't know about augment-base? I.e. from a server perspective, leaf d isn't actually mandatory. Thanks, Rob On 28/11/2016 11:28, Bogaert, Bart (Nokia - BE) wrote: Assume the following. module base-class { prefix base; container base { leaf a; leaf b; leaf c; } } module augment-base { prefix aug; import base-class { prefix base; } augment '/base:base'{ leaf d; } } module base-deviation { prefix base-dev; deviation "/base:base" { deviate add { must "./aug:d" { error-message "A value for d must be present when configuring augmented base"; } } } Best regards - Vriendelijke groeten, Bart Bogaert Broadband-Access System Architect Data Contact number +32 3 2408310 (+32 477 673952) NOKIA Copernicuslaan 50, 2018 Antwerp, Belgium Fortis 220-0002334-42 VAT BE 0404 621 642 Register of Legal Entities Antwerp << This message (including any attachments) contains confidential information intended for a specific individual and purpose, and is protected by law. If you are not the intended recipient, you should delete this message. Any disclosure, copying, or distribution of this message, or the taking of any action based on it, is strictly prohibited without the prior consent of its author. -----Original Message----- From: Juergen Schoenwaelder [mailto:[email protected] <mailto:[email protected]> ] Sent: 28 November 2016 12:09 To: Bogaert, Bart (Nokia - BE) <mailto:[email protected] <mailto:[email protected]> > <[email protected] <mailto:[email protected]> > Cc: [email protected] <mailto:[email protected]> <mailto:[email protected] <mailto:[email protected]> > Subject: Re: [netmod] Mandatory leafs via augment On Mon, Nov 28, 2016 at 10:42:42AM +0000, Bogaert, Bart (Nokia - BE) wrote: How can we achieve the same if no when-clause can be constructed but we still would like to have a leaf to be mandatory. One way we thought of achieving this is - have a YANG module defining the augmented data - construct a must statement on the object being augmented where we check that something needs to be present that is added via a deviation. An example may help here... /js _______________________________________________ netmod mailing list [email protected] <mailto:[email protected]> <mailto:[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
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