Subject: SAP Business Application Studio (BAS)
The Cloud Application Programming Model (CAP) is SAP’s framework for building enterprise-grade, scalable cloud applications quickly and efficiently. It provides a consistent approach to defining data models, business logic, and service layers using modern development standards and tools.
One of the foundational tasks when working with CAP in SAP Business Application Studio (BAS) is defining your data models and services effectively. This article guides you through the core concepts and best practices for designing data models and exposing services within the CAP framework.
In CAP, the data model defines the structure of the application data, similar to how a database schema works but with a higher level of abstraction. CAP uses Core Data Services (CDS) syntax—an industry-standard modeling language—to describe entities, their relationships, and constraints in a concise and platform-independent way.
.cds file (e.g., schema.cds) inside the db folder.Example:
namespace my.bookshop;
entity Books {
key ID : UUID;
title : String(111);
author : Association to Authors;
stock : Integer;
}
entity Authors {
key ID : UUID;
name : String(111);
country : String(50);
}
Example:
annotate Books with {
@UI.LineItem: [{Value: title}, {Value: author.name}]
}
Services expose your data and business logic over standard protocols such as OData or REST.
srv folder, create a .cds file (e.g., service.cds).Example:
using my.bookshop as db from '../db/schema';
service CatalogService {
entity Books as projection on db.Books;
entity Authors as projection on db.Authors;
}
srv folder with a cat-service.js file that implements custom handlers.Example:
module.exports = cds.service.impl(function() {
const { Books } = this.entities;
this.after('READ', Books, (each) => {
if(each.stock < 5) {
each.title += ' (Low Stock)';
}
});
});
| Best Practice | Description |
|---|---|
| Modularize CDS models | Split large models into smaller, maintainable files |
| Use Associations effectively | Model real-world relationships accurately |
| Leverage Annotations | Enhance UI and API behaviors without coding |
| Keep Service Definitions Lean | Expose only necessary entities and actions |
| Implement Custom Logic Sparingly | Avoid overcomplicating service handlers |
Defining clear, well-structured data models and services is key to building robust SAP CAP applications. With SAP Business Application Studio, developers have a streamlined environment that supports CDS modeling, service definition, and implementation seamlessly.
Mastering these concepts enables rapid development of scalable, maintainable cloud applications that integrate effortlessly within the SAP ecosystem.