CAP Java Tutorial - Student Manager

A complete SAP CAP Java application demonstrating how to build, test, and deploy an OData V4 service to SAP BTP Cloud Foundry.

🎯 What You'll Learn

• Define data models using CDS (Core Data Services)
• Create OData V4 services with automatic CRUD operations
• Add custom business logic with Java event handlers
• Configure local development with H2 database and mock authentication
• Deploy to SAP BTP with HANA, XSUAA, and other cloud services

📁 Project Structure

cap-tutorial/
├── README.md                    # This file
├── presentation_script.md       # Full workshop presentation script
└── student-manager/             # CAP Java application
    ├── pom.xml                  # Parent Maven POM
    ├── package.json             # CDS dependencies
    ├── mta.yaml                 # Deployment descriptor
    ├── xs-security.json         # XSUAA security config
    ├── db/
    │   ├── schema.cds           # Data model
    │   └── package.json         # HDI deployer config
    ├── srv/
    │   ├── pom.xml              # Service module POM
    │   ├── service.cds          # Service definition
    │   └── src/main/
    │       ├── java/            # Java source code
    │       └── resources/       # Configuration files
    └── approuter/               # Application Router
        ├── package.json
        └── xs-app.json

🚀 Quick Start

Prerequisites

• Node.js ≥18
• Java JDK 17+
• Maven 3.8+
• @sap/cds-dk (npm install -g @sap/cds-dk)

Run Locally

# Clone the repository
git clone git@github.com:AlexTsvetkov/cap-tutorial.git
cd cap-tutorial/student-manager

# Install dependencies
npm install

# Build and run
mvn clean spring-boot:run -pl srv

Test the API

The application runs at http://localhost:8080

Authentication: Basic Auth with admin/admin or user/user

Endpoint	Description
/odata/v4/StudentService/$metadata	OData metadata
/odata/v4/StudentService/Students	List all students
/odata/v4/StudentService/Students?$filter=status eq 'ACTIVE'	Filter students

Example: Create a Student

curl -X POST http://localhost:8080/odata/v4/StudentService/Students \
  -u admin:admin \
  -H "Content-Type: application/json" \
  -d '{
    "firstName": "John",
    "lastName": "Doe",
    "email": "john.doe@example.com",
    "status": "ACTIVE"
  }'

🏗️ Architecture

┌─────────────────────────────────────────┐
│           Local Development             │
│  ┌─────────────┐    ┌────────────────┐  │
│  │  Spring Boot │    │   H2 Database  │  │
│  │  + CAP Java  │───▶│  (in-memory)   │  │
│  └─────────────┘    └────────────────┘  │
│        │                                 │
│        ▼                                 │
│  Mock Authentication (Basic Auth)       │
└─────────────────────────────────────────┘

┌─────────────────────────────────────────┐
│           SAP BTP Cloud Foundry         │
│  ┌─────────────┐    ┌────────────────┐  │
│  │  Approuter  │───▶│  Java Backend  │  │
│  └──────┬──────┘    └───────┬────────┘  │
│         │                   │           │
│         ▼                   ▼           │
│  ┌─────────────┐    ┌────────────────┐  │
│  │   XSUAA     │    │  HANA Cloud    │  │
│  │  (OAuth2)   │    │ (HDI Container)│  │
│  └─────────────┘    └────────────────┘  │
└─────────────────────────────────────────┘

📚 Documentation

• steps.md - Step-by-step implementation guide
• presentation_script.md - Full workshop script with explanations

🔧 Key Technologies

Technology	Purpose
SAP CAP	Application programming model
CDS	Data modeling language
Spring Boot	Java runtime framework
OData V4	REST API protocol
HANA	Production database
XSUAA	OAuth2 authentication

📦 Deploy to SAP BTP

# Login to Cloud Foundry
cf login -a https://api.cf.us10-001.hana.ondemand.com

# Build MTA archive
mbt build

# Deploy
cf deploy mta_archives/student-manager_1.0.0.mtar

🔗 Resources

• CAP Java Documentation
• CDS Language Reference
• SAP BTP Trial Account
• CAP Samples on GitHub

📄 License

This project is licensed under the MIT License.