[wildfly-dev] Management Model: Squatter Resources
Jason Greene
jason.greene at redhat.com
Thu Oct 30 10:12:18 EDT 2014
It sounds like in this case min/max is unnecessary because of the 1:1 address to name relationship. I think Jeff’s case is easily solved by returning fully qualified address based resource definitions. For example, if you do:
/subsystem=messaging=*:read-resource-definition
If the result contained nested N sets of resource definitions, as previously discussed, it’s all pretty straight forward.
> On Oct 30, 2014, at 9:00 AM, Brian Stansberry <brian.stansberry at redhat.com> wrote:
>
> I'm not so sure that bad idea was yours.
>
> But +1 on getting rid of the existing min/max thing.
>
> On 10/30/14, 8:58 AM, David M. Lloyd wrote:
>> Using schema-ish things like min/max was probably a bad idea on my part.
>> After trying to model XML schema in various ways for various reasons
>> over the years, I know now that the simpler our rules are, the easier it
>> will be to implement a cohesive and useful UX.
>>
>> IMO any currently unused and un-useful constructs like this that are
>> hanging around probably need to be pruned, before someone actually uses
>> them and makes everyone's live more difficult. :-)
>>
>> On 10/30/2014 08:44 AM, Brian Stansberry wrote:
>>> No, we don't. That currently would have to be handled in a custom way by
>>> the OSH that does the add for any of the children.
>>>
>>> There are some bits and pieces in the metadata that can help with doing
>>> some sort of automated validation (i.e. a currently basically unused
>>> max/min child count thing) but I don't think what's there is sufficient.
>>>
>>> The fact the metadata isn't there means a client like the console
>>> couldn't enforce the constraint server side, for a better UX.
>>>
>>> On 10/30/14, 8:08 AM, David M. Lloyd wrote:
>>>> I mean, a single child where there can be many possible types for that
>>>> child.
>>>>
>>>> On 10/30/2014 08:01 AM, David M. Lloyd wrote:
>>>>> I think that polymorphism is a new use case for 'squatters'. I wonder
>>>>> if we have any existing code which enforces single children?
>>>>>
>>>>> On 10/30/2014 05:40 AM, Jeff Mesnil wrote:
>>>>>> I’m integrating HornetQ 2.5 in WildFly and I have a new use case for resources that is related to singleton/squatter resources.
>>>>>>
>>>>>> In HornetQ 2.5 they have completely rewritten the HA configuration. Basically, a server can be configured as live-only, replicated (master, slave, or colocated) or using shared-store (again as a master, slave or colocated).
>>>>>>
>>>>>> To represent this in the management model, I have added several resources under hornetq-server:
>>>>>>
>>>>>> /subsystem=messaging/
>>>>>> hornetq-server=*/
>>>>>> ha-policy=live-only
>>>>>> ha-policy=replicated-master
>>>>>> ha-policy=replicated-slave
>>>>>> ha-policy=replicated-colocated
>>>>>> ha-policy=shared-store-master
>>>>>> ha-policy=shared-store-slave
>>>>>> ha-policy=shared-store-colocated
>>>>>>
>>>>>> I have constraints for this ha-policy resource:
>>>>>> * There can at most one child for this type of resource (no child means no HA). This is enforces during the MODEL stage.
>>>>>> * The child can only be named using one of the 7 values above (i.e. there is no resource definition for ha-policy=*, using any other name would fail)
>>>>>>
>>>>>> Each ha-policy definition has a different set of attributes. Using an attribute group to represent the HA policy does not seem a good fit as some of them have subresources too.
>>>>>>
>>>>>> I wonder if that representation fits with our roadmap and whether it can be considered as a singleton (as there can only be one resource of that type among). I have the additional constraints of having only one chile for that type that is not covered by your proposal though.
>>>>>>
>>>>>> I especially wonder how the console (and to a lesser extent the cli) can deal with this resource.
>>>>>>
>>>>>> Heiko, is it something that would make sense for the console based on this resource description:
>>>>>>
>>>>>> [standalone at localhost:9990 hornetq-server=default] ./ha-policy=*:read-resource-description(recursive-depth=1)
>>>>>> {
>>>>>> "outcome" => "success",
>>>>>> "result" => [
>>>>>> {
>>>>>> "address" => [
>>>>>> ("subsystem" => "messaging"),
>>>>>> ("hornetq-server" => "default"),
>>>>>> ("ha-policy" => "replication-colocated")
>>>>>> ],
>>>>>> "outcome" => "success",
>>>>>> "result" => {
>>>>>> ...
>>>>>> }
>>>>>> },
>>>>>> {
>>>>>> "address" => [
>>>>>> ("subsystem" => "messaging"),
>>>>>> ("hornetq-server" => "default"),
>>>>>> ("ha-policy" => "replication-master")
>>>>>> ],
>>>>>> "outcome" => "success",
>>>>>> "result" => {
>>>>>> ...
>>>>>> }
>>>>>> },
>>>>>> {
>>>>>> "address" => [
>>>>>> ("subsystem" => "messaging"),
>>>>>> ("hornetq-server" => "default"),
>>>>>> ("ha-policy" => "shared-store-slave")
>>>>>> ],
>>>>>> "outcome" => "success",
>>>>>> "result" => {
>>>>>> ...
>>>>>> }
>>>>>> },
>>>>>> {
>>>>>> "address" => [
>>>>>> ("subsystem" => "messaging"),
>>>>>> ("hornetq-server" => "default"),
>>>>>> ("ha-policy" => "live-only")
>>>>>> ],
>>>>>> "outcome" => "success",
>>>>>> "result" => {
>>>>>> ...
>>>>>> }
>>>>>> },
>>>>>> {
>>>>>> "address" => [
>>>>>> ("subsystem" => "messaging"),
>>>>>> ("hornetq-server" => "default"),
>>>>>> ("ha-policy" => "shared-store-master")
>>>>>> ],
>>>>>> "outcome" => "success",
>>>>>> "result" => {
>>>>>> ...
>>>>>> }
>>>>>> },
>>>>>> {
>>>>>> "address" => [
>>>>>> ("subsystem" => "messaging"),
>>>>>> ("hornetq-server" => "default"),
>>>>>> ("ha-policy" => "replication-slave")
>>>>>> ],
>>>>>> "outcome" => "success",
>>>>>> "result" => {
>>>>>> ...
>>>>>> }
>>>>>> },
>>>>>> {
>>>>>> "address" => [
>>>>>> ("subsystem" => "messaging"),
>>>>>> ("hornetq-server" => "default"),
>>>>>> ("ha-policy" => "shared-store-colocated")
>>>>>> ],
>>>>>> "outcome" => "success",
>>>>>> "result" => {
>>>>>> ...
>>>>>> }
>>>>>> }
>>>>>> ]
>>>>>> }
>>>>>>
>>>>>> jeff
>>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
>
> --
> Brian Stansberry
> Senior Principal Software Engineer
> JBoss by Red Hat
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--
Jason T. Greene
WildFly Lead / JBoss EAP Platform Architect
JBoss, a division of Red Hat
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