[wildfly-dev] Management Model: Squatter Resources
Brian Stansberry
brian.stansberry at redhat.com
Thu Oct 30 11:16:43 EDT 2014
I shouldn't have mentioned min/max, as my only point was that it was a
crusty thing out there that doesn't really address the problem.
In this case, yes, there could be a 1:1 address to name relationship,
but there is nothing in our metadata that describes that only one of
those addresses can legally exist in a given tree.
We have an "alternatives" description for the requirement for a choice
amongst attributes, but nothing like that for resources.
On 10/30/14, 9:15 AM, Jason Greene wrote:
> Wow I am error-prone in the morning!
>
> "1:1 address to name relationship”
>
> -> 1:1 address to description relationship
>
> "/subsystem=messaging=*:read-resource-definition”
>
> -> subsystem=messaging=*:read-resource-description
>
>> On Oct 30, 2014, at 9:12 AM, Jason Greene <jason.greene at redhat.com> wrote:
>>
>> 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
>>> _______________________________________________
>>> wildfly-dev mailing list
>>> wildfly-dev at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/wildfly-dev
>>
>> --
>> Jason T. Greene
>> WildFly Lead / JBoss EAP Platform Architect
>> JBoss, a division of Red Hat
>>
>
> --
> Jason T. Greene
> WildFly Lead / JBoss EAP Platform Architect
> JBoss, a division of Red Hat
>
--
Brian Stansberry
Senior Principal Software Engineer
JBoss by Red Hat
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