An OAuth 2.0 client enables you to access services offered by of a service provider, for example, SAP HANA Cloud Platform, Google Cloud Platform, Microsoft Azure, or any other cloud service. The service provider's services are protected by OAuth 2.0.
The Application Server ABAP takes on the role of an OAuth 2.0 client. Using the OAuth 2.0 client, end users can access and consume services, for example, HTML 5 applications, that do not directly request data using an XMLHttpRequest (XHR) and delegate this request to the AS ABAP. A service provider provides the service, which is reachable from an Application Server ABAP acting as an OAuth 2.0 server. In addition, the OAuth 2.0 client can provide AS ABAP-based resources that end users can consume in the service provider. This requires access tokens that are suitable for the AS ABAP and the service provider. To request an access token, you can use one of the following grant types:
SAML 2.0 bearer assertion (grant type extension)
Please also make sure that you implement SAP Note 2043775 .
For more information, see the related link.