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gh-secondsky-sap-skills-ski…/references/cap-development.md
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CAP Development Reference

Overview

SAP Cloud Application Programming Model (CAP) is SAP's recommended framework for building enterprise-grade applications on SAP BTP using Node.js or Java.

Operational Profiles

CAP provides three operational profiles for different development stages:

Development Profile

Database: SQLite (Node.js) / H2 (Java)

Features:

  • Rapid prototyping with minimal setup
  • Mocked variants of SAP BTP services (authentication, database, messaging, app gateway)
  • No BTP subscription required
  • Cost-effective testing

Usage:

cds watch  # Automatically uses development profile

Hybrid Profile

Database: Cloud services (e.g., SAP HANA Cloud)

Features:

  • Run application locally
  • Bind to real cloud services for integration testing
  • Use cds bind or local configuration files
  • Test with production-like data

Usage:

cds bind --to hana:my-hana-instance
cds watch --profile hybrid

Production Profile

Database: SAP HANA Cloud

Features:

  • Deployed to SAP BTP (Cloud Foundry or Kyma)
  • Platform-managed service bindings
  • Production configuration for logging and security
  • Database migrations via cds deploy

Usage:

cds build --production
cf deploy mta_archives/my-app.mtar

Profile Summary

Profile Database Use Case
Development SQLite/H2 Local prototyping, mock services
Hybrid Cloud services Local app with cloud DB/services
Production SAP HANA Cloud Full cloud deployment

Supported Languages and Runtimes

Language Framework Runtime Options
Node.js Express.js Cloud Foundry, Kyma
Java Spring Boot Cloud Foundry, Kyma
TypeScript Node.js Cloud Foundry, Kyma

Development Tools

Tool Purpose
SAP Business Application Studio Primary cloud IDE
Visual Studio Code Local development with CDS extension
IntelliJ IDEA Java CAP development
CDS CLI Command-line development

Core CDS Commands

# Initialize new project
cds init my-project

# Add features
cds add hana          # SAP HANA Cloud support
cds add xsuaa         # Authentication
cds add mta           # MTA descriptor
cds add helm          # Helm charts for Kyma
cds add multitenancy  # Multitenant support
cds add approuter     # Application router

# Development
cds watch             # Run with live reload
cds build             # Build for deployment
cds deploy            # Deploy to HANA

# Service inspection
cds compile           # Compile CDS models
cds serve             # Start services

Domain Modeling with CDS

Entity Definition

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);
  books  : Association to many Books on books.author = $self;
}

Service Definition

using my.bookshop from '../db/schema';

service CatalogService {
  @readonly entity Books as projection on bookshop.Books;
  entity Authors as projection on bookshop.Authors;

  action submitOrder(book: Books:ID, quantity: Integer);
}

CAP Design Principles

Domain-Driven Design

  • Focus on core domain logic
  • Align code structure with business concepts
  • Collaboration between technical and domain experts

Agnostic Design

CAP abstracts:

  • Deployment approaches
  • Authentication strategies
  • Protocols (REST, OData, GraphQL)
  • Asynchronous channels
  • Database technologies

Out-of-the-Box Integration

  • SAP HANA Cloud for persistence
  • Authorization management services
  • Connectivity tools for external systems

Platform Integration

Database Support

Database Use Case
SQLite Development (Node.js)
H2 Development (Java)
PostgreSQL Production alternative
SAP HANA Cloud Production (recommended)

Service Bindings

# mta.yaml service binding example
modules:
  - name: my-srv
    type: nodejs
    requires:
      - name: my-hana
      - name: my-xsuaa
      - name: my-destination

resources:
  - name: my-hana
    type: com.sap.xs.hdi-container
  - name: my-xsuaa
    type: org.cloudfoundry.managed-service
    parameters:
      service: xsuaa
      service-plan: application

Microservices Architecture

CAP supports microservice development with:

  • Separate lifecycles per service
  • Independent runtimes
  • Event-based communication

Considerations:

  • Microservices introduce complexity
  • Potential performance trade-offs
  • Start monolithic, extract when needed

API Consumption

Supported Protocols

  • OData V2/V4
  • REST
  • OpenAPI

SAP Cloud SDK Integration

Generate typed client (recommended approach):

# Generate OData client from service specification
npx @sap-cloud-sdk/generator --input ./API_BUSINESS_PARTNER.edmx --outputDir ./generated

Use generated client:

// Import from generated client (path depends on generator output)
const { businessPartnerApi } = require('./generated/business-partner-service');

// Fetch business partners from S/4HANA
const businessPartners = await businessPartnerApi
  .requestBuilder()
  .getAll()
  .execute({ destinationName: 'S4HANA' });

Note

: The @sap/cloud-sdk-vdm-* packages are deprecated. Use @sap-cloud-sdk/generator to generate typed clients from OData service specifications. See SAP Cloud SDK documentation for details.

Multitenancy

Enable Multitenancy

cds add multitenancy

Key Features

  • Tenant isolation
  • Per-tenant database schemas
  • Subscription lifecycle hooks
  • Resource sharing across tenants

SaaS Entry Points

Approach Description Consumer Requirements
Central SAP Build Work Zone managed Own Work Zone instance
Local Standalone app router None

Extensibility

In-App Extensions

// Extend existing service
extend service CatalogService with {
  entity CustomEntity {
    key ID : UUID;
    customField : String;
  }
}

Custom Handlers

// srv/cat-service.js
module.exports = (srv) => {
  srv.before('CREATE', 'Books', async (req) => {
    // Validation logic
    if (!req.data.title) {
      req.error(400, 'Title is required');
    }
  });

  srv.on('submitOrder', async (req) => {
    // Custom action implementation
    const { book, quantity } = req.data;
    // Process order...
  });
};

Security Implementation

Authentication

// Require authentication
service CatalogService @(requires: 'authenticated-user') {
  entity Books as projection on bookshop.Books;
}

Authorization

// Role-based access
service AdminService @(requires: 'admin') {
  entity Books as projection on bookshop.Books;

  @(restrict: [{ grant: 'READ', to: 'viewer' }])
  entity Reports { ... }
}

Built-in Security Features

  • Parameterized queries (SQL injection prevention)
  • CSRF protection for UI applications
  • CDS constraints for input validation

Testing

Unit Testing with Jest

const cds = require('@sap/cds');

describe('CatalogService', () => {
  let srv;

  beforeAll(async () => {
    srv = await cds.connect.to('CatalogService');
  });

  it('should return books', async () => {
    const books = await srv.read('Books');
    expect(books).toBeDefined();
  });
});

Integration Testing

# Run tests
npm test

# With coverage
npm test -- --coverage

Deployment Commands

Cloud Foundry

# Build MTA
mbt build

# Deploy
cf deploy mta_archives/my-project_1.0.0.mtar

# Or with cf push for simple apps
cf push

Kyma

# Add Helm support
cds add helm

# Deploy with Helm
helm upgrade --install my-app ./chart

Common Issues and Solutions

Issue Cause Solution
HANA deployment fails Wrong HDI container Verify requires in mta.yaml
Authentication errors XSUAA not bound Run cf bind-service
Database connection refused Wrong profile Set NODE_ENV=production
Model compilation errors CDS syntax Run cds compile --to json for details

Source Documentation

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