The OData Protocol
OData is a protocol based on REST which provides the means to provide CRUD (create, read, update, delete) functionality to applications implemented as calls to remote APIs over HTTP. It defines best practices and improves the interoperability of APIs through specific document types such as service and metadata documents. OData services use the entity data model and the Common Schema Definition Language (CSDL). OData offers functions such as complex filtering, pagination, and free-text search.
The latest version is OData v4, but OData v2 is still supported, especially by SAP. In the SAP ecosystem, back-end technologies are used to provide OData APIs, while front-end technologies mainly work with OData.
OData is favored for synchronous integrations, for example, in SAP S/4HANA, where it replaces BAPI technology. Although SOAP is still used for asynchronous integrations, there are efforts to use OData here as well. It is important to note that other SAP products, such as SAP NetWeaver and SAP Business Suite, also support OData.