8:21 a.m.
On 12/10/14, 3:59 AM, Emmanuel Hugonnet wrote:
Maybe we should also group attributes by their attribute group names
instead of displaying them per natural sorting ?
This is what I meant by
"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."
I used the verb "sorted" though because I have no intent of modifying
the output structure by creating a level for the attribute group. That
would be an incompatible change in the output format and would obscure
the distinction between an attribute group and a complex attribute.
Is aliasing to be supported ? What if I want to change the attribute
group name ?
Good question.
Heiko, I don't think Emmanuel is talking about users changing this. We
use aliasing in other contexts as a mechanism for maintaining
compatibility. If something is poorly named (e.g. a bad resource address
name) we can fix it in a later release but also register an alias under
the old name to provide compatibility.
I don't see how aliasing could work here. Only thing I can imagine is
using it in the ls -l output, such that the same attribute can appear >
1 times, if it is associated with more than 1 group. I suppose a console
could do a similar thing, but I don't at all regard maintaining that
kind of compatibility in UI layout to be a requirement.
I'm not sure how much we regard consistency in the ls -l output across
releases as being a requirement. I think of that as being an output
format for humans, not machines.
Aliasing is an example of a reason for allowing an attribute to belong
to more than one group. There may be others. Perhaps as an aid to querying?
Emmanuel
Le 09/12/2014 21:00, Brian Stansberry a écrit :
> Off and on we've had discussions around the idea of "attribute
groups".
> We've got some use cases that are crying out for such a thing[1], 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
> console.
>
> 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
> resource.
>
> 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
it
> 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