[wildfly-dev] Management Model: Squatter Resources

[David M. Lloyd]

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
>>
>

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