Adding of a new field product:availability

[ogaquiere]

Add 'availability' field to define the direct availability of item's assets for download. Authorized values are "online' or "offline'.
It could be extended with other possible values in the future.

More details in Readme

[Scartography]

I like this, I understand that availability: online/offline is used quite widely. My suggestion would be to use simple boolean of product:available: TRUE/FALSE as there might be known or unknown reasons why the data is there or not and this would simply indicate status of STAC item it describes.

A bool gets a nice tick or cross in STAC browser:

[Scartography]

Also maybe instead of just having this information at item level, let it be possible to have this information at asset level as well?

[ogaquiere]

@Scartography

Thanks for your feedback.

About your first proposition, the objective is to add more values for this field in the future, even if the first use meets a need for Long Term Archiving. Thus we could have the following first 2 values :

• online
• archived (instead on offline)

About your second point, indeed, it would be useful to allow it at asset level. I will change in this way.

[Scartography]

I would find it appealing to work with flags (bools) here maybe mostly due to machine readability (developers accessing/evaluating data).

I am aware that the common practice is that of values you are suggesting, so this more to consider and use whats best.

Don't know if archived as available or not, but I can image having both as some data providers will be able to still have data available when archived and some not, thus individual flags might go a long way. Food for thought.

[m-mohr]

For context: The property is very similar or related to:

• published/expired/unpublished - especially unpublished seems to cater for the same usecase, just slightly differently
• order:status
• storage:tier (was in 1.0.0, but has been removed in 2.0.0)

[emmanuelmathot]

Agreed with Matthias.
From what I read in the README PR, I would see that information as a derived information from order extension and fall into the Activating offline assets use case.

[mario-winkler]

I would like to add some context:

This PR stems from the discussion around the new STAC-based interfaces for the Copernicus ground segment services, especially the LTA service, where a strict separation of semantics between products and orders exists. The intention of product:availablility was to reflect this at catalog level and to avoid a mixin of any order related information in the product metadata.

Also, as LTA clients are generally more interested in products and their online/offline states, not deriving this information from other properties was considered more appropriate. Apart from that I agree, that this falls into the activating offline assets use case.