[jboss-as7-dev] problems with deployment overlays and linking

[Alexey Loubyansky]

Another issue related to this command and management of the overlay and 
links is that this command can't be a part of a batch because actions 
like create a new overlay with content and adding content to an existing 
overlay can't translate into a single composite operation, which a batch 
translates to.

The problem is referencing results of one step in a composite operation 
from arguments of another step in the same composite operation.

Alexey

On 08/15/2012 04:11 PM, Alexey Loubyansky wrote:
> I've been prototyping a CLI command that manages deployment overlays and
> got worried :)
>
> I think, the current representation (actually, the data structure, in
> other words) of the overlays and their linking in the management model
> will lead to a lot of issues related to consistency of the data and
> complicate management of deployments in general.
>
> Basically, it's a many-to-many relationship between overlays and
> deployments. Currently, overlays and deployments are defined separately
> and linked using the "third table", each row of which consists of a link
> name, overlay name and deployment name (or deployment name regex). (BTW,
> I understand this design is not random, there were reasons to organize
> it this way but I'd like to raise my concerns).
>
> Which is a common practice in a relational database design but our
> management model is not as sophisticated, yet :) We don't have:
> - foreign key constraints (again, yet, I know Brian is going to look
> into that);
> - no cascade-delete;
> - no queries (e.g. by node attributes).
>
>
> CREATING A LINK AND LOOKING FOR IT
>
> To create a link between an overlay and a deployment, I have to come up
> with a name for it, which has to be unique, like a primary key. Well, I
> chose the format overlay_name-deployment_name. Then, in CLI, I rely on
> this format to search for the link(s), since searching by resource
> attributes turns out to be much more complicated, although possible.
> Actually, even searching using this naming format by deployment name or
> an overlay name is not that smooth. So, the CLI now expects a specific
> naming format. Taking into account that the CLI is not the only
> management tool and that any application or user can manage things
> "manually", it'd be good for all the users and tools to agree on the
> naming format, which is not practical.
>
> REMOVING A DEPLOYMENT
>
> Until now it was about removing only the deployment. Now, not to run
> into inconsistencies in the model, the "third table" has to be searched
> for references and cleaned up if found.
>
> Removing an overlay leads to the same consequences, of course, which is
> unavoidable anyway. But I think we could re-organize the model to
> minimize the risks or running into inconsistencies and simplify management.
>
> ALTERNATIVE STRUCTURES
>
> I discussed these issues with Emanuel, who agreed and had in mind
> another idea to represent this in the model, which I actually find more
> logical and elaborate. I'll let him follow up and describe it in details.
>
> Thanks,
> Alexey
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