OData: Communication between SAPUI5-Apps and SAP Backend

The Open Data Protocol (OData) is a Web protocol based on the REST (Representational State Transfer) principles and is used to process requests and updates of data from various sources in the SAP back end. Web technologies such as HTTP (Hypertext Transfer Protocol), AtomPub (Atom Publishing Protocol), and JSON (JavaScript Object Notation) are used.
SAPUI5 applications do not access the back end directly, but via the SAP Gateway Client, which provides the OData service. Using the SAP Gateway Client, it is possible to program in a standardized way using Smart Controls and to securely display or change data from the back end. Smart Controls enable functions that have been developed once to be used several times. Smart controls are graphical elements (such as input fields) in the SAPUI5 apps that are maintained in the abstract data model of the SAP Gateway Client. The SAPUI5 applications can adopt the properties of Smart Controls using the metadata from the OData data model.
An OData service can be addressed platform-independently using the SAP Gateway client. It is called using URIs (Uniform Resource Identifiers), which determine which OData service is called with which data model.
According to the REST guidelines, the OData service can be called using the following requests:

• GET: Determine a single entry or a list of entries
• POST: Create a new entry
• PUT: Change an existing entry
• DELETE: Delete an existing entry
• PATCH: Update individual attributes of an existing entry

Thus, the use of OData for mobile applications is imminent, as this service is particularly flexible in terms of data origin, platform use and standards for use