[wildfly-dev] Management Model: Squatter Resources

[Jeff Mesnil]

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

-- 
Jeff Mesnil
JBoss, a division of Red Hat
http://jmesnil.net/