Question on API interactions leveraging order extension

[carguel]

Hi,

The documentation provided by the Github repository is not really detailed regarding the API interactions between the Client and the STAC Catalog. I have some questions regarding how to implement a server leveraging order extension, for example :

1. where the href field that provides the link to trigger the ordering process shall be located (in the item links section or in the asset definition) ?
2. If it is in the links section, what shall be the relation name ?
3. Are all interactions performed through GET HTTP requests or POST HTTP request, at least for the creation of the order ?

So basically, is there a more formal specification that defines how the client shall interact with the catalog to perform a complete order ?

Thank you for your support.

Christophe

[teije01]

Hello Christophe,

I have no authority on this extension, but I can share how we decided on these factors in our own project:

1. We felt that the best place to add the href is in the item.links section for an orderable item may not already have the assets defined that it will have once it is succeeded
2. we came up with rel="order"
3. Since the order endpoint has side effects and does not only return server-side content, we argued for POST.

[teije01]

And perhaps this sections does answer: https://github.com/stac-extensions/order?tab=readme-ov-file#relation-types

• that the relation is indeed 'order'
• and it should be part of the item.links (following the link to the item spec).

[m-mohr]

The API interaction is indeed not described yet and needs an API extension or a simple new relation type, but it could also be potentially aligned with https://github.com/stapi-spec/stapi-spec or https://github.com/Open-EO/openeo-api/tree/master/extensions/commercial-data or anything that may be defined within OGC.

Please note that (afaik) the order relation type is not meant to be used to execute orders, but instead it should just return additional (meta)data about the order, before or after the execution of the order. Do you agree @emmanuelmathot ?

[emmanuelmathot]

Yes the order extension is really on STAC spec side as a generic schema to handle order metadata. The relationship type "order" was meant to be more an additional info link and should maybe be renamed properly.