Monday, December 14, 2015

Core Data Services (CDS)

Within raising significance of SAP HANA there needed to be programming frameworks introduced to speed up accessing data in database to SAP applications. This is purpose of Core Data Services (CDS) which is an infrastructure for defining and consuming semantically rich and reusable data models. Modern SAP apps like SAP Business Suite or SAP S/4HANA are leveraging the CDS as it represents data layer for them. Framework around the CDS supports creation of reusable data models in database instead of the ABAP server. Similarly it supports consumption of these data models.

The data models are defined in ABAP programs as CDS views. By dealing with the CDS views the ABAP program has an access to the data in the data model. The view implements a semantic data model in the ABAP Dictionary. It allows to define entity types (business objects like customer, order, ...) and semantic relationships between these objects. The relationships correspond to foreign key relationships in traditional entity relationship (ER) models. Technically the CDS uses SQL-based DDL language to literally describe the relations. Moreover there are additions to DDL e.g. associations, which define the relationships between CDS views, and annotations, which direct the domain-specific use of CDS artifacts. By having described the semantics by the annotations we can use data and data types in different contexts (e.g. UI, analytics, searching).

The CDS was introduced within SPS 05 for SAP NetWeaver 7.4. In NetWeaver 7.5 there are more than 6k SAP standard view definitions that can be leveraged. This number of the CDSs keeps growing plus there more and more functionality being added in new SPS of NetWeaver 7.5.

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