Re: [netmod] Action and RPC statements

[Martin Bjorklund <[e-mail]>]

Lou Berger <[e-mail]> wrote:
> Martin,
> 
> If I have an RPC or action that changes state, how would the
> persistence of that state be indicated with an NMBA data stores.  I
> expected it to be related to the data store, but I read your mail
> below as saying otherwise

The side effects of executing an rpc or action is described in the
rpc/action itself.  This is not a problem.  For example, see the
definition of <edit-config>.  So with NMDA, this continues to work
like before.


/martin




> Thanks,
> Lou
> 
> 
> On November 6, 2017 8:20:12 AM Martin Bjorklund <[e-mail]>
> wrote:
> 
> > Hi,
> >
> > Trying to summarize this issue.
> >
> > The problem is which datastore is used to:
> >
> >     1a. evaluate action ancestor nodes
> >     1b. evaluate action input/output parameter leafref,
> >         instance-identifier, must, when
> >     2.  evaluate rpc input/output parameter leafref,
> >         instance-identifier, must, when
> >
> > (Note that the side effects of an action/rpc is not part of this
> > issue)
> >
> > I think it would be very weird if 1a and 1b were treated differently,
> > so I just label them as 1 below.
> >
> > Possible solutions:
> >
> > A.  Always use <operational> for 1 and 2.
> >
> >     (This is what the current nmda draft says).
> >
> > B.  Let the client specify the datastore for 1, and use <operational>
> >     for 2.
> >
> >     (Note that this is trivial in RESTCONF (since the datastore is
> >     part of the URL), but would require a new parameter for NETCONF
> >     (or a new <action2>).
> >
> > C.  Let the client specify the datastore for 1 and 2.
> >
> >     This would require a new generic parameter for how RPCs are
> >     invoked in both NETCONF and RESTCONF.
> >
> > D.  Like B, but let the description of the "rpc" statement optionally
> >     override this.
> >
> >
> > I prefer B and then D.
> >
> >
> > /martin
> >
> >
> >
> >
> > Andy Bierman <[e-mail]> wrote:
> >> On Thu, Nov 2, 2017 at 2:16 PM, Phil Shafer <[e-mail]> wrote:
> >>
> >> > Sorry, if I wasn't clear.  I meant the <datastore> element would
> >> > be directly under <action>, so the system knows where to start
> >> > looking for data.  Guessing is bad.
> >> >
> >> >
> >> Totally agree guessing is bad.
> >> Did you see the <action2> proposal in a previous email?
> >> That is exactly what I proposed, except I do not want to
> >> overload <action> so the new template would be a different name.
> >>
> >> I realize the expanded name of the datastore element prevents it from
> >> being confused with top-level YANG nodes, but the conformance
> >> is more clear with a new name.
> >>
> >>
> >>
> >>
> >> > Thanks,
> >> >  Phil
> >> >
> >>
> >> Andy
> >>
> >>
> >> >
> >> >
> >> > Andy Bierman writes:
> >> > >So a server will be required to guess the correct datastore until it
> >> > >finds the right one that matches the action instance?
> >> > >
> >> > >   <action>
> >> > >       <top>
> >> > >          <list1>
> >> > >             <key>10</key>
> >> > >             <do-test>
> >> > >                <datastore>candidate</datastore>
> >> > >             </do-test>
> >> > >          </list1>
> >> > >        </top>
> >> > >    </action>
> >> > >
> >> > >The server will guess the datastore in some proprietary order and
> >> > >parse
> >> > >instances of /top/ and /top/list1.  Then it finds the <do-test> action
> >> > >and parses the input to get to the datastore and find out the real
> >> > datastore
> >> > >to use.  If the server guessed wrong, then it reparses the <action>
> >> > against
> >> > >the requested datastore.  Hopefully the schema trees match up.
> >> > >
> >> > >Will vendors do all the extra work required to support this sort of
> >> > >thing?
> >> > >I doubt it.
> >> > >
> >> > >
> >> > >Andy
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >On Tue, Oct 31, 2017 at 11:36 PM, Phil Shafer <[e-mail]>
> >> > >wrote:
> >> > >
> >> > >> Robert Wilton writes:
> >> > >> >ii) However, as far as I can see, it doesn't make sense for an action
> >> > to
> >> > >> >directly affect the contents of any configuration datastore, that
> >> > should
> >> > >> >be done via a purpose built rpc (like edit-config).
> >> > >>
> >> > >> An example action would be to retrieve the  fingerprint of an ssh
> >> > >> key.  I might want to get the fingerprint of a key in <candidate>
> >> > >> before I commit it.
> >> > >>
> >> > >> Or I could have an action that sets the SNMPv3 auth key to a random
> >> > >> value, and I want to invoke that action against <candidate>.
> >> > >>
> >> > >> Seems like <startup> might also be an interesting place to target
> >> > >> actions, but I can't think of a good example.
> >> > >>
> >> > >> There are always scenarios where something is useful, and the problem
> >> > >> with ruling it out is that it becomes needed at some later point.
> >> > >> We've a habit of ruling out things and later wishing we had them.
> >> > >>
> >> > >> Is the easy fix to just put a datastore leaf under rpc/action and
> >> > >> have it default to operational?  Any specific RPC can define its
> >> > >> own datastore leaf of hard-code the database in the description
> >> > >> (explicitly or implicitly <operational>), but the <action> RPC only
> >> > >> gets this if we make a new parameter for it.
> >> > >>
> >> > >> Thanks,
> >> > >>  Phil
> >> > >>
> >> > >
> >> > >--001a11411b0ad2d58d055cee96cb
> >> > >Content-Type: text/html; charset="UTF-8"
> >> > >Content-Transfer-Encoding: quoted-printable
> >> > >
> >> > ><div dir=3D"ltr">Hi,<div><br></div><div>So a server will be required
> >> > >to
> >> > gue=
> >> > >ss the correct datastore until it</div><div>finds the right one that
> >> > matche=
> >> > >s the action instance?</div><div><br></div><div>=C2=A0
> >> > =C2=A0&lt;action&gt;=
> >> > ></div><div>=C2=A0 =C2=A0 =C2=A0 =C2=A0&lt;top&gt;</div><div>=C2=A0
> >> > =C2=A0 =
> >> > >=C2=A0 =C2=A0 =C2=A0 &lt;list1&gt;</div><div>=C2=A0 =C2=A0 =C2=A0
> >> > >=C2=A0 =
> >> > >=C2=A0 =C2=A0 =C2=A0&lt;key&gt;10&lt;/key&gt;</div><div>=C2=A0 =C2=A0
> >> > =C2=
> >> > >=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0&lt;do-test&gt;</div><div>=C2=A0 =C2=A0
> >> > =C2=
> >> > >=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 &lt;datastore&gt;candidate&lt;
> >> > /datas=
> >> > >tore&gt;</div><div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0
> >> > =C2=A0&lt;/do-=
> >> > >test&gt;</div><div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0
> >> > &lt;/list1&gt;</div><=
> >> > >div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 &lt;/top&gt;</div><div>=C2=A0 =C2=A0
> >> > &lt;/a=
> >> > >ction&gt;</div><div><br></div><div>The server will guess the datastore
> >> > in s=
> >> > >ome proprietary order and parse</div><div>instances of /top/ and
> >> > /top/list1=
> >> > >.=C2=A0 Then it finds the &lt;do-test&gt; action</div><div>and parses
> >> > >the
> >> > i=
> >> > >nput to get to the datastore and find out the real
> >> > >datastore</div><div>to
> >> > u=
> >> > >se.=C2=A0 If the server guessed wrong, then it reparses the
> >> > &lt;action&gt; =
> >> > >against</div><div>the requested datastore.=C2=A0 Hopefully the schema
> >> > trees=
> >> > > match up.</div><div><br></div><div>Will vendors do all the extra work
> >> > requ=
> >> > >ired to support this sort of thing?</div><div>I doubt
> >> > it.</div><div><br></d=
> >> > >iv><div><br></div><div>Andy</div><div><br></div><div><br></
> >> > div><div><br></d=
> >> > >iv><div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">On
> >> > >Tue,
> >> > O=
> >> > >ct 31, 2017 at 11:36 PM, Phil Shafer <span dir=3D"ltr">&lt;<a
> >> > href=3D"mailt=
> >> > >o:[e-mail]" target=3D"_blank">[e-mail]</a>&gt;</span>
> >> > wrote=
> >> > >:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0
> >> > .8ex;border-le=
> >> > >ft:1px #ccc solid;padding-left:1ex">Robert Wilton writes:<br>
> >> > >&gt;ii) However, as far as I can see, it doesn&#39;t make sense for an
> >> > acti=
> >> > >on to<br>
> >> > >&gt;directly affect the contents of any configuration datastore, that
> >> > shoul=
> >> > >d<br>
> >> > >&gt;be done via a purpose built rpc (like edit-config).<br>
> >> > ><br>
> >> > >An example action would be to retrieve the=C2=A0 fingerprint of an
> >> > >ssh<br>
> >> > >key.=C2=A0 I might want to get the fingerprint of a key in
> >> > &lt;candidate&gt=
> >> > >;<br>
> >> > >before I commit it.<br>
> >> > ><br>
> >> > >Or I could have an action that sets the SNMPv3 auth key to a
> >> > >random<br>
> >> > >value, and I want to invoke that action against &lt;candidate&gt;.<br>
> >> > ><br>
> >> > >Seems like &lt;startup&gt; might also be an interesting place to
> >> > target<br>
> >> > >actions, but I can&#39;t think of a good example.<br>
> >> > ><br>
> >> > >There are always scenarios where something is useful, and the
> >> > >problem<br>
> >> > >with ruling it out is that it becomes needed at some later point.<br>
> >> > >We&#39;ve a habit of ruling out things and later wishing we had
> >> > >them.<br>
> >> > ><br>
> >> > >Is the easy fix to just put a datastore leaf under rpc/action and<br>
> >> > >have it default to operational?=C2=A0 Any specific RPC can define
> >> > >its<br>
> >> > >own datastore leaf of hard-code the database in the description<br>
> >> > >(explicitly or implicitly &lt;operational&gt;), but the &lt;action&gt;
> >> > RPC =
> >> > >only<br>
> >> > >gets this if we make a new parameter for it.<br>
> >> > ><br>
> >> > >Thanks,<br>
> >> > >=C2=A0Phil<br>
> >> > ></blockquote></div><br></div></div></div>
> >> > >
> >> > >--001a11411b0ad2d58d055cee96cb--
> >> >
> >
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>