Hi Per,
*From:* Igor Bryskin [mailto:igor.brys...@huawei.com]
*Sent:* Sunday, October 8, 2017 7:04 PM
*To:* Igor Bryskin <igor.brys...@huawei.com>; p...@tail-f.com;
*xufeng.liu.i...@gmail.com
*Cc:* netc...@ietf.org; netmod@ietf.org
*Subject:* Re: [Netconf] [netmod] Retrieving Information Pointed by
*leafref
Hi Joel,
Thanks, I think I didnt explain our problem correctly.
In our case we have a leafref pointing to a te tunnel name, which
happens to be a key to lookup the (axilary) tunnel. We need a way to
include the entire tunnel body (not just a name) into the get
response. This is to optimize the number of iterations between the
client and the server. As Xufeng put it something similar to SQL join,
Igor
*From:*Igor Bryskin
*To:*p...@tail-f.com,xufeng.liu.i...@gmail.com,
*Cc:*netc...@ietf.org,netmod@ietf.org,
*Date:*2017-10-08 17:36:47
*Subject:*Re: [Netconf] [netmod] Retrieving Information Pointed by
*leafref
Hi Per,
In a nutshell we would lika for a netconf client to have a way to
instruct the server on whether in response to the get request the
server needs to provide the entire body of a datastore node pointed
to by a leafref or just a pointer to said node, so that the node's
body could be retrieved by a subsequent separate request. This is
requested by implementors who want to optimise rhe number of
interactions between a client and its server.
Cheers,
Igor
*From:*Per Hedeland
*To:*Xufeng Liu,
*Cc:*netc...@ietf.org,'NetMod WG',
*Date:*2017-10-08 14:01:27
*Subject:*Re: [Netconf] [netmod] Retrieving Information Pointed by
*leafref
On 2017-10-06 23:11, Xufeng Liu wrote:
During the design team discussion for TE and MPLS YANG modeling, we
have received a request from implementers: How to minimize the number
of NETCONF/RESTCONF RPCs to improve operation efficiency?
Especially for the case when the operator or client software needs to
retrieve the object contents pointed by a leafref.
For example, given the following simplified TE tunnel model,
+--rw te
+--rw explicit-paths
| +--rw explicit-path* [name]
| +--rw name string
| +--rw explicit-route-object* [index]
| +--rw index uint32
| +--rw explicit-route-usage? identityref
+--rw tunnels
| +--rw tunnel* [name]
| | +--rw name string
| | +--rw paths
| | | +--rw path* [name]
| | | +--rw explicit-path? ->
| | | ../../../../../explicit-paths/explicit-path/name
when the client tries to retrieve a tunnels information based on the
tunnel name, the get operation returns a list of leafrefs pointing
to the paths of the tunnel.
Sorry, I'm afraid I don't follow. Can you explain exactly what your
"get" request is (protocol and payload), and where the "list of
leafref's" (whatever that may be) occurs in the reply?
*/[Xufeng] The get operation is the NETCONF/RESTCON <get> protocol
*operation, or the <get-data> operation described in
*https://tools.ietf.org/html/draft-dsdt-nmda-netconf-01 and the GET
*operations
on {+restconf}/ds/<datastore> described in
https://tools.ietf.org/html/draft-ietf-netconf-nmda-restconf-00./*
*/ /*
*/We have a list of leafref values because in this example model, each
*tunnel contains a list of paths, each of them contains a leafref. The
* get returns a value for each instance of such a leafref,
which (as a string value) will be used as a constraint (foreign key)
to retrieve the instance of an explicit-path in the model above./*
JFYI, in case there is some fundamental misunderstanding here: a leaf
of
type leafref has a single value - *one* of those that satisfy the
leafref
constraint, in case there are multiple "candidates".
--Per
The client needs to issue at
least one more get operation to retrieve the path information about
the given tunnel. The request is to combine these two operations into
one.
In the RDBMS SQL world, join can be used when SQL select is
performed, but NETCONF/YANG currently does not have this capability.
Wed like to ask whether such a request is considered reasonable.
If the request is reasonable, the next question is how to
proceed. This seems to be a protocol issue rather than YANG modeling
issue. Is it acceptable to add a new operation to achieve such a
<get-data> operation with expanded leafrefs?
Comments and suggestions are appreciated.
Thanks,
- Xufeng
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