onboard GTN training to the EOSC Portal

The EOSC Portal offers two ways to onboard training resources:
1) via a web interface for each Resource individually, or
2) via the EOSC Portal API (you need to prepare the Resource description according to the EOSC Training Resource Profile https://wiki.eoscfuture.eu/display/PUBLIC/F.+EOSC+Training+Resource+Profile).

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> Having an API to expose the training resources, we would suggest to use the EOSC Portal API.
In brief, the Provider needs to use the AAI of the Portal to retrieve a new API token. Then, the Provider prepares the Resource description, according to the EOSC Training Resource Profile (https://wiki.eoscfuture.eu/display/PUBLIC/F.+EOSC+Training+Resource+Profile) by calling the API’s POST/Resource/validate method.
Upon successful validation, the Provider calls the POST/Resource method to add the new Resources in the catalogue. Upon success, the Provider receives a new set of Resource IDs and the new Resources are onboarded in the Portal.
A detailed description of the Portal Open API is available at https://providers.eosc-portal.eu/openapi.

Please see the following:
- user guide on how to onboard Training Resources into the EOSC Marketplace: https://wiki.eoscfuture.eu/display/PUBLIC/Step-by-step+guide%3A+How+to+onboard+Training+Resources+into+the+EOSC+Marketplace, and
- course on to onboard services/resources via the EOSC Portal API (here you will find detailed instructions about the onboarding focusing on the use of the API, see section 6): https://openplato.eu/course/view.php?id=61