Exercise: Querying SAP APIs in a Java Spring Application

In this exercise, you will learn how to query the Business Partner API of SAP S/4HANA Cloud. We will use the Mock Server instead of the actual SAP S/4HANA Cloud.

1. Checkout the branch javaspring_v1.2_query in SAP Business Application Studio

   1. Checkout the Git branch by running the following commands in the terminal:

      Code Snippet

      Copy codeSwitch to dark mode

      12
      cd ~/projects/cloud-sdk-learning-journey
      git checkout -f javaspring_v1.2_query

2. Build and run the project

   1. Build the application by running the following commands in the terminal

      Code Snippet

      Copy codeSwitch to dark mode

      12
      cd bpstandardvdm
      mvn clean install -Dmaven.test.skip=true

   2. Start the application by running the following commands in the terminal

      Code Snippet

      Copy codeSwitch to dark mode

      12
      cd application
      mvn spring-boot:run

      Note

      On the execution of the mvn command, we verified sometimes a "Compilation failure" error. As a workaround, just re-execute the command and the application will start correctly.

      Note

      As an alternative, to run the application, you can open the Application.java file. Choose Run → Start Debugging or press F5.

      

3. Make sure that the Mock Server is up and running as described in the related previous exercise.

   1. In case the Mock server is installed but not started, you need to open a new terminal window and run the following commands:

      Code Snippet

      Copy codeSwitch to dark mode

      12
      cd ~/projects/cloud-s4-sdk-book
      npm run start

4. Query the Business Partner API of the Mock Server

   1. Open the requests.http file

   2. Click on Send Request in the requests.http file to submit the GET request for business partners

      

   3. Stop the running application using Ctrl + C in the corresponding terminal window.

5. Optional: Query the Business Partner API of the sandbox in api.sap.com.

   1. Access https://api.sap.com/api/API_BUSINESS_PARTNER. Login and get your API Key.

      

   2. Open BusinessPartnerController.java file in the ~/projects/cloud-sdk-learning-journey/bpstandardvdm/application/src/main/java/com/sap/cloud/sdk/tutorial/controllers/ folder.

   3. Uncomment section of code to replace the URL property with https://sandbox.api.sap.com/s4hanacloud to retrieve business partners from SAP API Business Hub. Note that you also have to provide the API KEY

      

   4. Re-build and run the application:

      Code Snippet

      Copy codeSwitch to dark mode

      12345
      cd ~/projects/cloud-sdk-learning-journey/bpstandardvdm
      mvn clean install -Dmaven.test.skip=true
      cd application
      mvn spring-boot:run
      

   5. Re-test the Business Partners query in the requests.http file.

   6. Stop the running application using Ctrl + C in the corresponding terminal window.

6. Optional: Query the Business Partner API of your SAP S/4HANA Cloud, public edition tenant.

   1. Uncomment section of code to replace the URL property with https://my######.s4hana.ondemand.com.

   2. Enter proper URL, User and Password. The API Key is not required.

   3. Re-build and run the application.

   4. Re-test the Business Partners query in the requests.http file.

   5. Stop the running application using Ctrl + C in the corresponding terminal window.

7. Optional: code walk-through.

   1. review code in the following source files:

      File name	Comments on code changes
      BusinessPartnerController.java	Code logic is as follows... Annotate the method getBusinessPartners with @RequestMapping to handle the GET method Create a variable named destination of type HttpDestination with information about the Mock Server or API Business Hub Create an instance of the DefaultBusinessPartnerService class Call the getAllBusinessPartner method to retrieve the business partners Use the SAP Cloud SDK fluent API method chaining to provide additional parameters Return the list of business partners as part of the GET request
      requests.http	Provides various HTTP requests that can be submitted to query the Business Partner API
      commands.txt	Provides various commands that can be run on the terminal

      Note

      Review the exercise on SAP Tutorial Navigator on Connecting to OData Service on Cloud Foundry using SAP Cloud SDK. https://developers.sap.com/tutorials/s4sdk-odata-service-cloud-foundry.html

8. Optional: Manually re-create the project in ~/projects/bpstandardvdm.

   1. The following steps create an exact replica of the project you just checked out from Git. Step-by-step, without using Git.

   2. Generate a Spring Boot project using SAP Cloud SDK from scratch using the Maven archetype. Run the following command in the terminal

      Code Snippet

      Copy codeSwitch to dark mode

      12
      cd ~/projects
      mvn archetype:generate "-DarchetypeGroupId=com.sap.cloud.sdk.archetypes" "-DarchetypeArtifactId=spring-boot3" "-DarchetypeVersion=RELEASE" "-DartifactId=bpstandardvdm" "-DgroupId=com.sap.cloud.sdk.tutorial" "-Dpackage=com.sap.cloud.sdk.tutorial"

   3. Open the bpstandardvdm folder in the workspace.

      

   4. Delete the whole application/src/test subfolder.

   5. Create or update the files in the table below

      File name	Type	Contents
      API_BUSINESS_PARTNER.edmx Path: ~/projects/bpstandardvdm/application/edmx/	New	Copy contents from here
      pom.xml Path: ~/projects/bpstandardvdm/application/	Update	Copy contents from here
      BusinessPartnerController.java Path: ~/projects/bpstandardvdm/application/src/main/java/com/sap/cloud/sdk/tutorial/controllers/	New	Copy contents from here...
      serviceNameMappings.properties ~/projects/bpstandardvdm/	New	Copy contents from here...
      requests.http Path: ~/projects/bpstandardvdm/	New	Copy contents from here...

      

   6. Build and run the project in projects/bpstandardvdm.

      Code Snippet

      Copy codeSwitch to dark mode

      12345
      cd ~/projects/bpstandardvdm
      mvn clean install -Dmaven.test.skip=true
      cd application
      mvn spring-boot:run
      

      Note

      On the execution of the mvn command, we verified sometimes a "Compilation failure" error. As a workaround, just re-execute the command and the application will start correctly.

      Note

      Remove the application/src/test folder if it exists in the main folder before running mvn spring-boot:run

   7. Stop the running application using Ctrl + C in the corresponding terminal window.