Set Up SAP Business Application Studio for CAP Java

1. Change the color theme to your preferences.

   Go to File > Settings > Color Theme and choose an item from the list. We used Dark (Visual Studio).

   

2. From the main menu, choose Terminal > New Terminal.

   

3. A terminal window should now have been opened on the bottom of the window. From the terminal, run cd projects to go to the projects directory.

   

4. Now, run:

   mvn -B archetype:generate -DarchetypeArtifactId=cds-services-archetype -DarchetypeGroupId=com.sap.cds \
   -DarchetypeVersion=RELEASE \
   -DgroupId=com.sap.cap -DartifactId=products-service -Dpackage=com.sap.cap.productsservice
   

   This will initialize the application using the maven archetype cds-services-archetype and create your project as follows:

   • The project is named products-service.
   • The db folder stores database-related artifacts.
   • The srv folder stores your Java application.

   

5. From the main menu, choose File > Open Workspace.

6. Choose products-service and then Open.

   

   If you see a notification asking if you want to synchronize the Java classpath/configuration, choose Always.

   If you have any problem indication for any of the pom.xml files yet, don’t worry; ignore them for now.

CAP applications use Core Data Services (CDS) to describe:

• Data structures by using entity definitions
• How data structures are consumed by using service definitions

In this step, you’ll define a simple service, which also defines its own entity. In more complex applications, services usually expose projections on entities defined in the data model.

1. Right-click on the srv folder and choose New File.

   

2. Call it admin-service.cds and click OK to create the file.

3. Add the following service definition to the file and make sure you Save the file (keyboard shortcut CTRL+S):

   service AdminService {
       entity Products {
           key ID : Integer;
           title  : String(111);
           descr  : String(1111);
       }
   }
   

1. From the main menu, open a terminal with Terminal > New Terminal.
   You should be in the products-service project but in order to be sure run pwd.

   pwd
   

   

2. Run the following command in the terminal to trigger the maven build process:

   mvn clean install
   

Running this for the first time in a fresh dev space might take a while, depending on the network. Please wait until you see the BUILD SUCCESS message before continuing with the tutorial.

After running this command, some files are generated and added to the srv/src/main/resources/edmx folder. This is the default path, where CAP Java runtime looks for the model definitions.

While creating the project skeleton, the application Application.java file was created, which contains a main method. The Application.java is the startup class for the Spring Boot container.

1. Look at the Application.java in the com.sap.cap.productsservice package (file path: srv/src/main/java/com/sap/cap/productsservice).

   

   If you use CTRL+P in SAP Business Application Studio, you open a search bar. Start typing Application.java to find and open the file.

   As you can see, the file doesn’t contain CAP-specific startup instructions. It’s the typical boilerplate code found in every Spring Boot application. The initialization of the CAP Java runtime is done by Spring automatically, based on the dependencies defined in the pom.xml.

2. Go to the root of your project by running the following command in the terminal:

   cd ~/projects/products-service
   

3. Start the application:

   mvn clean spring-boot:run
   

   A notification message saying “A service is listening to port 8080” will appear in the bottom right.

   

   If you have issues exposing the port or opening the application, take a look at the next step where alternative ways to expose the port and open the application are explained.

4. Choose Expose and Open.

5. Provide app-port as the unique description.

6. Hit the Enter key to open the application in a new tab.