Currently, the support for substitution mapping is extremely limited. the substitution_mapping section is parsed and validated, but nothing more.
However, supporting this feature (and hence, allowing for service composition) is of high priority. Currently, we are at the the designing phase - going over the spec to identify vague and ambiguous parts, and consolidating TOSCA's pov regarding substitution mapping with the current ARIA implementation. Relevant Jira issue: https://issues.apache.org/jira/browse/ARIA-292 On Tue, Aug 8, 2017 at 11:03 PM, Steve Baillargeon < steve.baillarg...@ericsson.com> wrote: > Hi > I have looked at the data you have provided. > I am trying to catch up (understand) to current ARIA support for > substitution mapping. > What is supported today and what are the limitations/considerations? > What is missing (hence the need for full implementation)? > Do you have an working example or set of guidelines for using substitution > mapping today? > Or should I avoid it completely for now? > > - Steve B > > -----Original Message----- > From: Tal Liron [mailto:t...@cloudify.co] > Sent: Monday, August 07, 2017 8:41 PM > To: dev@ariatosca.incubator.apache.org > Subject: Re: Service Composition / Substitution Mapping > > Well, this is exactly what policies are for. :) > > Again, I think the rule of thumb should be that users put policies in place > *only* if the defaults do not suffice. > > On Mon, Aug 7, 2017 at 6:42 PM, Ran Ziv <r...@cloudify.co> wrote: > > > The sensible defaults Tal's mentioned sound indeed sensible to me. > > I'd also like users to have control over this, though I'm a bit > > worried about us getting too carried away with how arbitrarily we use > > policies for configuring, well, pretty much anything. It might not be > > a problem right now but I'm not certain that will remain the case in > > the future when the number of them grows.. > > > > > > On Wed, Aug 2, 2017 at 7:14 PM, Tal Liron <t...@cloudify.co> wrote: > > > > > Our goal with adding new "conventions" to ARIA, such as policies, is > > > to always make them optional. The idea is that a plain-vanilla TOSCA > > template > > > would "just work" in ARIA via sensible defaults. The extra stuff is > > > there if you know you are using ARIA and you want to make use of its > features. > > > (The opposite is true, too: we make sure that any additions are > > > still > > pure > > > TOSCA and would be parsed validly by other TOSCA parsers.) > > > > > > On Wed, Aug 2, 2017 at 9:08 AM, DeWayne Filppi <dewa...@cloudify.co> > > > wrote: > > > > > > > Cool. Missed that. That leaves things almost completely wide > > > > open > > from > > > > the orchestrator side, IOW few predefined keys. Too few IMHO, but > > > > if everyone uses ARIA conventions it could work. > > > > > > > > On Tue, Aug 1, 2017 at 11:49 PM, Tal Liron <t...@cloudify.co> wrote: > > > > > > > > > I agree! Luckily metadata exists in the 1.0 spec. :) > > > > > > > > > > http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile- > > > > > YAML/v1.0/cos01/TOSCA-Simple-Profile-YAML-v1.0-cos01.html#_ > > > Toc379455044 > > > > > > > > > > On Tue, Aug 1, 2017 at 7:16 PM, DeWayne Filppi > > > > > <dewa...@cloudify.co> > > > > > wrote: > > > > > > > > > > > It occurs that it might be useful to be able to tag service > > templates > > > > > with > > > > > > arbitrary meta-data. Perhaps at one level carried forward > > > > > > from a > > > CSAR > > > > > > manifest, but also user definable. This would allow > > > > > > inter-service references to be definitive, if desired. This > > > > > > could be implicitly > > > > > defined > > > > > > as a capability by the orchestrator, but some kind of special > > > > requirement > > > > > > type(s) would be needed to utilize it. This way, external > > > > > > repos > > > could > > > > be > > > > > > used safely and directly without the separate load step. > > > > > > > > > > > > On Tue, Aug 1, 2017 at 12:43 PM, Tal Liron <t...@cloudify.co> > > wrote: > > > > > > > > > > > > > Thanks for the kudos. :) > > > > > > > > > > > > > > This topic was discussed on this list a while ago. It's > > > > > > > indeed > > > tricky > > > > > to > > > > > > > get right, because TOSCA leaves a lot of room for the > > orchestrator > > > to > > > > > > > implement. > > > > > > > > > > > > > > I'm thinking of it working something like this: > > > > > > > > > > > > > > 1. The reqs-and-caps engine by default will always look for > > > > satisfiable > > > > > > > capabilities within the currently instantiated service. > > > > > > > HOWEVER, > > if > > > > > such > > > > > > a > > > > > > > capability is not present, the option is there to look for > > another > > > > > > > instantiated service that exposes the capabilities in > > substitution > > > > > > > mappings. > > > > > > > > > > > > > > 2. If we DON'T have another instantiated service, but DO > > > > > > > have a > > > > service > > > > > > > template that could fit the bill, perhaps we need to > > > > > > > instantiate > > > that > > > > > > other > > > > > > > service first. One obvious option is to do this automatically. > > But > > > I > > > > > feel > > > > > > > like this can create unforeseen consequences -- for example, > > > > > > > some > > > > dummy > > > > > > > test template that someone happened to have in the database > > > > > > > might > > > get > > > > > > > instantiated by mistake. Also, it might need to trigger > > > > > > > multiple > > > > > install > > > > > > > workflows at once... a big mess. So I suggest that instead > > > > > > > we > > > > provide a > > > > > > > very detailed validation error here saying that the > > > > > > > requirement > > > > cannot > > > > > be > > > > > > > satisfied, HOWEVER there exist service templates A, B, and C > > > > > > > that > > > can > > > > > > > substitute for us, so maybe the nice user would like to > > instantiate > > > > > them > > > > > > > first? This seems very reasonable to me. > > > > > > > > > > > > > > 3. If indeed another service satisfies this, a special node > > > > > > > is > > > added > > > > to > > > > > > the > > > > > > > current service (with the correct type -- but without a > > > > > > > service > > > > > template > > > > > > > foreign key), which serves as a proxy of the other service > > > template. > > > > > I'm > > > > > > > not sure how we would mark this exactly. We can't use the > > > service_fk > > > > > > field, > > > > > > > because it's still in our current service. So perhaps > > > > > > > there's > > need > > > > of a > > > > > > new > > > > > > > fk field, maybe substituted_service_fk? > > > > > > > > > > > > > > The above might be "sensible defaults," but it seems to me > > > > > > > that > > > users > > > > > > > really need control over this. So I propose to add a new > > > > > aria.Composition > > > > > > > policy that would let you provide hints for this mechanism. > > > > > > > For > > > > > example, > > > > > > > you might want to "filter" the target service by service > > > > > > > template > > > > name > > > > > > and > > > > > > > even by metadata in the service template. For example, you > > > > > > > might > > > want > > > > > to > > > > > > > require version 1.2.2 of a specific service, no less. > > > > > > > > > > > > > > Those are some quick thoughts. Exactly how such a policy > > > > > > > would > > look > > > > > with > > > > > > > require more thought... > > > > > > > > > > > > > > > > > > > > > On Tue, Aug 1, 2017 at 2:20 PM, Avia Efrat > > > > > > > <a...@cloudify.co> > > > wrote: > > > > > > > > > > > > > > > Hello all, > > > > > > > > > > > > > > > > I'm starting to work on a full implementation of > > > > > substitution_mapping, > > > > > > > > which will lead to the ability of service composition. > > > > > > > > > > > > > > > > For those unacquainted with substitution mapping, here are > > > > > > > > some > > > > quick > > > > > > > > resources: > > > > > > > > *From the spec > > > > > > > > <http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile- > > > > > > > > YAML/v1.0/TOSCA-Simple-Profile-YAML-v1.0.html>, > > > > > > > > sections:* > > > > > > > > 2.10 > > > > > > > > <http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile- > > > > > > > > YAML/v1.0/os/TOSCA-Simple-Profile-YAML-v1.0-os.html#_ > > > > Toc471725208>, > > > > > > > > 2.11 > > > > > > > > <http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile- > > > > > > > > YAML/v1.0/os/TOSCA-Simple-Profile-YAML-v1.0-os.html#_ > > > Toc471725209> > > > > > > > > (theory and examples) > > > > > > > > 3.8.1, 3.8.2 (grammar) > > > > > > > > *From Tal's amazing lecture on TOSCA > > > > > > > > <https://www.youtube.com/watch?v=6xGmpi--7-A>:* > > > > > > > > 00:00 until 12:30. > > > > > > > > > > > > > > > > If anyone wishes to: > > > > > > > > * ask questions regarding this feature > > > > > > > > * suggest real-life use cases > > > > > > > > * offer their insight about vague parts of the spec > > > > > > > > * anything else about substitution mapping and service > > > composition > > > > > > > > Then please, feel encouraged to leave your feedback! > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
