Understanding SAP HANA Core Data Services (CDS) 

Use SAP HANA Core Data Services (CDS) to build design-time, data-persistence models in SAP HANA Extended Application Services.

The SAP HANA Core Data Services (CDS) Reference explains how to use SAP HANA CDS to define and consume semantically rich, design-time data models in SAP HANA. The model described in CDS enables you to use the Data Definition Language to define the artifacts that make up the design-time, data-persistence model. The data is exposed in response to client requests via HTTP, for example, from an SAPUI5-based application.

Data Persistence Model in SAP HANA

The persistence model defines the schema, tables, sequences, and views that specify what data to make accessible for consumption by XS applications and how.

In SAP HANA Extended Application Services (SAP HANA XS), the persistence model is mapped to the consumption model that is exposed to client applications and users so that data can be analyzed and displayed in the appropriate form in the client application interface. The way you design and develop the database objects required for your data model depends on whether you are developing applications that run in the SAP HANA XS classic or XS advanced run-time environment.

• SAP HANA XS Classic Model
• SAP HANA XS Advanced Model

SAP HANA XS classic mode

SAP HANA XS classic model enables you to create database schema, tables, views, and sequences as design-time files in the SAP HANA repository. Repository files can be read by applications that you develop. When implementing the data persistence model in XS classic, you can use either the Core Data Services (CDS) syntax or HDBtable syntax (or both). “HDBtable syntax” is a collective term; it includes the different configuration schema for each of the various design-time data artifacts, for example: schema (.hdbschema), sequence (.hdbsequence), table (.hdbtable), and view (.hdbview).

All repository files including your view definition can be transported (along with tables, schema, and sequences) to other SAP HANA systems, for example, in a delivery unit. A delivery unit is the medium SAP HANA provides to enable you to assemble all your application-related repository artifacts together into an archive that can be easily exported to other systems.

SAP HANA XS Advanced Model

For the XS advanced run time, you develop multi-target applications (MTA), which contain modules, for example: a database module, a module for your business logic (Node.js), and a UI module for your client interface (HTML5). The modules enable you to group together in logical subpackages the artifacts that you need for the various elements of your multi-target application. You can deploy the whole package or the individual subpackages.