I think we should support arbitrary objects for tags. Users should use only 
tags they understand, so it's fine to have free-form tags in there.
The problem with tag objects in YAML is that we can't use DSL - because  the 
tags need to be resolved pretty early, while constructing the EntitySpec when 
there are no running entities. So Futures/Tasks/DeferredSuppliers should not be 
allowed for tag values.
On the other hand YAML lists, maps could be useful.

Svet.


> On 31.03.2017 г., at 11:49, Valentin Aitken 
> <[email protected]> wrote:
> 
> Hi,
> 
> I'd like to bring attention to a new feature I suggested in BROOKLYN-460 [1] 
> and [2].
> Current requirement is to be able to supply String tags in an entity spec in 
> YAML so it can be then retrieved via REST API with GET 
> /v1/applications/<appId>/entities/<entityId>/tags.
> 
> Example usage in a YAML blueprint:
> services:
> - type: org.apache.brooklyn.entity.software.base.VanillaSoftwareProcess
>  brooklyn.tags:
>  - tag1
>  - "2"
>  - hello world
> 
> Please shout if you have further requirements for brooklyn.tags.
> 
> Main concern raised in [2] comments is whether that syntax should support any 
> Object as a tag.
> 
> My concern is that although Object is allowed
> in Apache Brooklyn only classes defined in 
> org.apache.brooklyn.core.mgmt.BrooklynTags are used as a tag.
> Every entity has this tag at the moment:
> [{"kind":"yaml_spec","contents":"services:\n- type......"}]
> 
> That is good since REST query for tags in every entity will have "kind" field 
> which someone can rely on.
> Good use case is to very easy filter out kind -> yaml_spec and making sure 
> user can retrieve only tags assigned in YAML.
> That's why I decided to follow the same pattern and in YAML and accept
> string values only which are then passed to 
> org.apache.brooklyn.core.mgmt.BrooklynTags.newNotesTag
> in order to keep existing pattern with "kind" and "contents" fields for every 
> tag.
> 
> 
> [1] https://issues.apache.org/jira/browse/BROOKLYN-460
> [2] https://github.com/apache/brooklyn-server/pull/612
> 
> -- 
> Valentin Aitken
> Software Engineer
> Cloudsoft Corporation Ltd.
> www.cloudsoft.io
> 

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