[katello-devel] Katello Backend Service Relationships and Architecture

[Eric D Helms]

On Thu, Dec 6, 2012 at 10:45 AM, Tom McKay <thomasmckay at redhat.com> wrote:

>
>
> ----- Original Message -----
> > From: "Eric D Helms" <ericdhelms at gmail.com>
> > To: katello-devel at redhat.com
> > Sent: Wednesday, December 5, 2012 9:20:06 PM
> > Subject: [katello-devel] Katello Backend Service Relationships and
>  Architecture
> >
> >
> > They say a picture is worth a thousands words, and after, for lack of
> > a better word, being bugged by the differences in backend service
> > integration I decided to try and spell out the current lay of the
> > land. I have attempted to do this in two ways. The first being a
> > diagram showing how our models, glue and controllers are laid out in
> > relation to backend services with arrows indicating the directional
> > awareness that one entity has with another. For example, an arrow
> > pointing from glue/candlepin to resources/candlepin since
> > glue/candlepin has direct knowledge of the resources but not vice
> > versa. Second, I have attempted to quell out into bullet points how
> > each backend service is currently (and by this I mean as of PulpV2
> > branch) integrated.
> >
> >
> > Disclaimer: This is my understanding of things and there are places
> > where I could have gotten something wrong or mis-represented that
> > actual implementation
> >
> >
> >
> > Reference Diagram:
> >
> https://docs.google.com/drawings/d/1lK-BozdUbTBJPnvSv40uCtzy4_Y1qUZCIJesq_pqsHY/edit
> >
> >
> > Note: This is taking into consideration the changes made in the
> > PulpV2 branch and current Candlepin and Foreman work in master
> >
> >
> >
> >
> > PulpV2
> >
> >
> > - All Pulp functionality is contained within app/models/glue/pulp
> > - All glue layers are modules that are included into the Katello
> > model if use_pulp = true
> > - Katello Models are treated as the main entity, with Pulp glue layer
> > adding functionality if included
> > - Even non-persisted objects have a top-level representation in
> > Katello (e.g. errata, package, distribution)
> > - Nothing is proxied
> > - Basic functionality is orchestrated (CRUD)
> > - Use of callbacks and hooks to trigger top-level events that can be
> > listened to by glue layer
> > - There is no notion of pulp outside the glue layer
> >
> >
> >
> >
> > Candlepin
> >
> >
> > - Contains a single Candlepin only model without corresponding
> > inclusion in a Katello entity (OwnerInfo)
> > - Contains some proxied functionality mainly for subscription manager
> > - Not all Candlepin functionality is contained in glue layer
> > - Basic functionality is orchestrated (CRUD)
> >
>
> Definitely room for clean-up in the candlepin layer. I would love to see
> us move to align with the clean pulp v2 integration style.
>
> From what we learned cleaning-up the Pulp layer for V2 integration, doing
the same for the Candlepin side shouldn't be too difficult or
time-consuming.

-Eric


> >
> >
> >
> > Foreman
> >
> >
> > - Foreman is front and center at all layers
> > - Controllers for API and UI are under foreman/ and namespaced
> > - Models are under foreman/ and are classed as Foreman::
> > - Katello models that have corresponding Foreman model also get a
> > separate model file besides their glue layer counterpart (i.e.
> > models/foreman/user)
> > - Other models have lightweight representations and are entirely pass
> > through objects down to Foreman but are not top-level Katello
> > entities
> > - Glue layer is fenced off and only included if use_foreman set to
> > true
> >
> >
> >
> >
> > ElasticSearch
> >
> >
> > - All ES functionality is contained within
> > app/models/glue/elasticsearch
> > - All glue layers are modules that included into the corresponding
> > Katello model
> > - Adds functionality but does not directly impart itself into the
> > models
> > - Use of callbacks and hooks to trigger top-level events that can be
> > listened to by glue layer
> >
> >
> >
> >
> > I am hoping this will spark some discussion, as I worry that the
> > differences in integration points for each backend service will only
> > make our lives as developers more difficult down the road.
> >
> >
> > -Eric
> > _______________________________________________
> > katello-devel mailing list
> > katello-devel at redhat.com
> > https://www.redhat.com/mailman/listinfo/katello-devel
>
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