Add identification of Global Caches to WNM

[kaiwirt]

Note: sections marked with * are required.

Overview of proposal*

For the metrics exported by a Global Cache there is the problem on how to identify the data source. Currently the URL of the href is used for this which leads to several problems. During the WIS2-to-GTS-Gateway test meeting it was proposed to use the centre-id of the data source in the metrics. For WIS2 Nodes this is the centre-id value of the Topic. However if the data is retrieved from a Global Cache there is no identification of the Global Cache available.
Thus, the WNM message should be extended by an (optional) properties.cache-id which is set by Global Caches with their centre-id.

Amendment details*

Add an optional properties.cache-id to the WNM specification.
Update the Manual and Guide Section of Global Caches such that: Global Caches SHALL add an properties.cache-id to cache WNM specifying the centre-id of the Global Cache that emitted this WNM

Requestor(s)*

@kaiwirt

Consultations

See section 3.6 of the above mentioned meeting report

Comments

[tomkralidis]

TT-WISMD 2025-03-19:
Options for naming:

1. properties.cache_id
2. properties.global-cache_id
3. properties.cache-centre-id
4. other options?

[tomkralidis]

Propose option 2. global-cache aligns with how centre-id's of global services are identified.

[tomkralidis]

PR in #157

[amilan17]

wmo-im/wis2-guide#43