Application Programming Interface or API

Application Programming Interface or API is?an interface provided by an application for interacting with other applications. APIs specify how software programs are able to exchange information with each other, even if designed and run by different organizations.

SAP Cloud Platform API management?provides simple, scalable and secure access to digital assets through application programming interfaces (APIs) and enables developer communities to consume these.

API in S4 - S/4HANA API is a concept somehow similar to BAPIs known from SAP ECC systems. The difference here is that in the S/4HANA they are?RESTful APIs and use the oData protocol, whereas BAPIs were mainly called using RFC connection (if called from outside of SAP).

APIs are needed?to bring applications together in order to perform a designed function built around sharing data and executing pre-defined processes. They work as the middleware, allowing developers to build new programmatic interactions between the various applications people and businesses use on a daily basis.

There are three categories of API protocols or architectures:?REST, RPC and SOAP.

A REST API is?Representational State Transfer Application Programming Interface that conforms to the constraints of REST architectural style and allows for interaction with RESTful services. REST APIs provide a simple, lightweight way to expose CRUD operations over HTTP,?OData is a more comprehensive protocol for querying and updating data, with a rich set of features for accessing and modifying data, complex types and relationships, custom operations, and more standardized querying

RPC APIs?allow developers to call remote functions in external servers as if they were local to their software. For example, you can add chat functionality to your application by remotely calling messaging functions on another chat application.

Simple object access protocol?(SOAP) is an official protocol maintained by the World Wide Web Consortium (W3C). The main difference is that SOAP is a protocol while REST is not. Typically, an API will adhere to either REST or SOAP, depending on the use case and preferences of the developer.

The OData API is implemented as a REST API?and the technical protocol is Open Data Protocol (OData). This means that you can use standard HTTP methods (for example, the GET method) to call the API.

SAP OData ?(Open Data Protocol) API - An application programming interface allows you to access data (such as monitoring data for example). The API is implemented as a REST API and the technical protocol is?Open Data Protocol?(OData). This means that you can use standard HTTP methods (for example, the GET method) to call the API.

OData is?an ISO/IEC approved, OASIS standard that defines a set of best practices for building and consuming RESTful APIs.

OData is?a resource-based web protocol for querying and updating data. OData defines operations on resources using HTTP commands (for example, GET, PUT , POST , and DELETE ) and specifies the uniform resource indicator (URI) syntax to use to identify the resources.

Difference between API and EDI in SAP - EDI is used for exchanging structured business data between trading partners' EDI systems, while APIs are used for integrating and communicating between different software applications for real-time data exchange.

References:

SAP Business Accelerator Hub - https://api.sap.com/api/OP_API_BUSINESS_PARTNER_SRV/resource/Business_Partner

How to find an API on SAP S/4HANA OP (EN) | SAP Blogs - https://blogs.sap.com/2020/06/11/how-to-find-an-api-on-sap-s-4hana-op-en/

ODATA V4 | SAP S/4HANA Cloud | SAP Business Accelerator Hub - https://api.sap.com/products/SAPS4HANACloud/apis/ODATAV4