This issue describes a concrete proposal on how to realise attributes reuse through yaml syntax and tooling.

Related issues / PRs:

• Add geo fields from ECS into client and server attributes semantic-conventions#351
• Adding a few browser related attribute conventions semantic-conventions#559

Proposal

I'm proposing to introduce a new, additional type of attribute reference called embed (alternatively: nest) in the syntax that would behave similarly to ref property BUT with the following difference: When embed is used the referenced attribute will be nested under the namespace of the attribute group in which the attribute is being referenced.

Example

See the following example that illustrates the idea and the difference to ref:

We would define geo attributes in a geo.yaml file:

groups:
  - id: geo
    prefix: geo
    type: attribute_group
    brief: Describes the geo location
    attributes:
      - id: location.lon
        type: double
        brief: Longitude of the geo location in [WGS84](https://en.wikipedia.org/wiki/World_Geodetic_System#WGS84).
        examples: [ -73.614830 ]
      - id: location.lat
        type: double
        brief: Latitude of the geo location in [WGS84](https://en.wikipedia.org/wiki/World_Geodetic_System#WGS84).
        examples: [ 45.505918 ]

In client and server files we would embed the attributes.
! Note: Here I consciously embed the geo.location.lon attribute BUT ref the geo.location.lat attribute to demonstrate the difference:

groups:
  - id: client
    prefix: client
    type: attribute_group
    brief: ...
    attributes:
      - id: address
        ...
      - embed: geo.location.lon            <<-- THAT IS NEW
      - ref: geo.location.lat

When rendering (or code generating) the above it will result in the following attributes:

• client.geo.location.lon
• geo.location.lat

Note the difference that geo.location.lon is now nested under the client namespace because it was embedded (embed) while geo.location.lat keeps it's original full name because it was referenced (ref).

Extended proposal

We could even think about an embed_namespaces property on the attribute_group level to simplify embeddings of entire namespaces into other namespace. For example for geo we could do something like the following to embed ALL of the geo.* fields into the client:

groups:
  - id: client
    prefix: client
    type: attribute_group
    brief: ...
    embed_namespaces:
      - id: geo                                        <<-- EMBED the entire geo namespace under client
    attributes:
      - id: address
        ...