In the URL of your service you can use the origin segment parameter o to expose the system alias. However, there can be different system aliases for one backend system if you use multiple origin composition. With multiple origin composition you can have access to several backend systems to retrieve data and might not necessarily want to use system aliases but instead use a combination of system ID and client. If you also want to create OData requests you might not have information on any SAP Gateway system alias. Therefore, SAP Gateway also supports OData requests with a combination of system ID and client as backend origin.
In addition, you might wish to refrain from thus exposing the system name of your SAP Gateway system in the URL of your service for security reasons. In this case, instead of the system name you can also use the system ID (SID) together with the corresponding client.
Sample syntax for system alias: /sap/opu/odata/IWBEP/TEA_TEST_APPLICATION;o=XYZ_999/Teams
Sample syntax for system ID and client: /sap/opu/odata/IWBEP/TEA_TEST_APPLICATION;o=sid(XYZ.999)/Teams
The processing is as follows:
The SAP Gateway system searches for all existing system aliases for the user and the specified service.
The SAP Gateway system checks if one from above system aliases equals sid(XYZ.999). If this is the case, this system will be used.
If no such system exists underneath the specified service, then SAP Gateway checks whether one of the above system aliases has defined a system ID XYZ and client 999.
If this is the case, this system ID will be used. Otherwise an error message is displayed.
For each system alias you need to enter also a system ID and a client, if this has not yet been configured already. For more information, see Creating the SAP System Alias for Applications.