This proposal is a great idea. Let’s do it :)
I can probably have a branch with the "Proposed Work" bit, excluding the
CLI ls -l thing, done today or tomorrow. It went quicker than I thought.
But the more important part is any discussion here. The CLI ls -l thing
I don't want to code yet because I don't have a strong feeling about
> On Dec 9, 2014, at 2:00 PM, Brian Stansberry
> Off and on we've had discussions around the idea of "attribute
> We've got some use cases that are crying out for such a thing, so I'd
> like to propose doing something concrete but simple for these for WF 9,
> ideally in the next month.
> A big part of my goal here is to ensure that whatever we do doesn't
> preclude something more advanced in any next generation management
> stuff, e.g. David's stuff.
> PART I Concepts
> 1) What is an attribute group?
> The "attribute group" concept I propose is simply a collection of
> attributes associated with the same resource type that are independently
> configurable but are statically declared to be conceptually related. The
> group has a name, and members. The name provides a brief indication of
> the nature of the relationship.
> The goal is to provide information to the user to help them better
> understand the relationship between attributes. In particular,
> management tools could use this information to visually present related
> attributes together, e.g. in a tab or other grouping widget in the web
> 2) What isn't an attribute group?
> Something relevant to writes.
> 3) Why would I use a child resource instead of an attribute group?
> Because the attributes control a discrete piece of functionality and you
> need to be able to turn that on or off as a unit. So you add/remove the
> 4) Why would I use a complex attribute with a bunch of fields instead of
> n>1 simple attributes in a group.
> a) Because the attributes control a discrete piece of functionality and
> you need to be able to turn that off as a unit. So users can undefine
> the complex attribute.
> b) Because it's a common use case that modifications to n>1 of the
> fields should be done atomically and you don't want to force users to
> use a CLI batch. So you let them use write-attribute and specify the
> value of all the fields.
> 5) Why would I use an attribute group instead of a child resource?
> Because requiring users to add a child resource just to set a bunch of
> values that are really part of the config of the parent resource forces
> them to use a CLI batch to correctly configure the parent resource.
> 6) Why would I use an attribute group instead a complex attribute?
> Because the various attributes should be independently configurable. In
> particular, wiping out the config for all of them by simply undefining
> the complex attribute isn't appropriate.
> PART II Proposed Work
> 1) The basics
> We add a piece of metadata to the read-resource-description output for
> an attribute. Name is 'attribute-group', value type is ModelType.STRING,
> value is the name of the group, with 'undefined' allowed.
> The group is simply the set of attributes that share the same string.
> To implement this, we add public String
> AttributeDefinition.getAttributeGroup() and add support for setting it
> to the relevant Builder. ReadResourceDescriptionHandler outputs the value.
> 2) XML parsing/marshalling
> Modify PersistentResourceXMLDescription such that attributes in an
> attribute group get persisted in their own child element, whose name is
> the name of the group.
> PersistentResourceXMLBuilder exposes a setter to allow users to turn
> this on/off for that resource. Turning it off will allow the addition of
> attribute group settings for a resource without requiring an immediate
> corresponding xsd change.
> 3) Web console
> HAL can make use of the additional metadata at its leisure, and as it
> becomes available.
> 4) Low level management API
> The output of read-resource and read-resource-description is modified
> such that attributes are sorted by group name and then by attribute name.
> 5) CLI
> I'm not clear on exactly what to do here, but my instinct is the output
> of the 'ls -l' command should be modified. Probably add a GROUP column
> to the right and sort the order of attributes by group and then by
> attribute name.
> PART III Other possible things to do
> A :read-attribute-group(name=<groupname>) operation or an
> "attribute-groups=[<groupname>*]" param to :read-resource, to make
> convenient to read a set of attributes without needing to read the
> entire resource.
> We could also consider adding an "attribute-groups" section to the
> read-resource-description output, where a fuller i18n text description
> of the meaning of the group could be written. If we do this we should
> probably do it in WF 9 as it will likely add some sort of requirement to
> subsystem authors that we expose right from the start.
> If you're still awake, comments as always are appreciated.
> Brian Stansberry
> Senior Principal Software Engineer
> JBoss by Red Hat
>  For example, the JDKORB pull request at
uses child resources in a
> number of places where it seems like attribute groups are a better fit.
> wildfly-dev mailing list
Jason T. Greene
WildFly Lead / JBoss EAP Platform Architect
JBoss, a division of Red Hat