Exercise: Implementing Caching in a Java Spring Application

In this exercise, you will learn how to implement caching in SAP Cloud SDK application. We will use the Mock Server instead of the actual SAP S/4HANA Cloud.

1. Enable caching in the application you created in the previous exercise.

   1. Checkout the initial Git branch javaspring_v3.0_caching. To do this, open a Terminal and run the following commands, make sure current working directory is /home/user/projects/cloud-sdk-learning-journey.:

      Code snippet

      Copy code

      pwd
      git checkout -f javaspring_v3.0_caching

      Expand

      

2. Build and run the project

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

      Code snippet

      Copy code

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

      Expand

   2. Open the Application.java file. Press F5 to run the application

      

3. Start the Mock Server

   1. In the Terminal, run the following commands

      Code snippet

      Copy code

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

      Expand

4. Query the Business Partner API of SAP S/4HANA Cloud

   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. Verify that the list of business partners are returned from the Mock Server

   4. Stop the Mock Server by pressing Ctrl + C in the Mock Server project terminal

   5. Click on Send Request in the requests.http file to submit the GET request for business partners within 30 seconds

   6. Verify that the list of business partners are returned from the cache, since the Mock Server is not running

      

   7. Click on Send Request in the requests.http file to submit the GET request for business partners after 30 seconds

   8. Verify that an empty list of business partners is returned due to resilience configuration

      

5. Optional: Review code in the following source files

   1. Note

      Check out the exercise on SAP Tutorial Navigator on Introducing caching to your application. https://developers.sap.com/tutorials/s4sdk-caching.html

      Code walk-through

      File name	Comments on code changes
      GetBusinessPartnersCommand.java	Code logic is as follows... Determine how long objects need to be cached. In our example, we will cache the objects for 30 seconds Declare parameters that need to be stored together with cached data. In our example, we are building the cache without any parameters
      pom.xml	Code logic is as follows... Use the JCache adapter Caffeine, but you can use any implementation you like Add the Caffeine dependency to your application
      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

6. Optional: Manually create the project. The following steps create an exact replica of the project you just checked out using Git.

   Note

   Before you execute this step, you must execute the corresponding optional step, described in the previous Implementing resilience in a Java Spring application exercise.

   1. Create or update the following files in the table below

      File name	Type	Contents
      GetBusinessPartnersCommand.java Path: bpstandardvdm/application/src/main/java/com/sap/cloud/sdk/tutorial/utils	Modified	Copy contents from here...
      pom.xml Path: bpstandardvdm/application	Modified	Copy contents from here...

      

   2. Build and run the project in projects/bpstandardvdm in the same exact way you did in the previous steps with project in projects/cloud-sdk-learning-journey/bpstandardvdm.