Welcome to CAP Samples for Java

Welcome to the bookshop-java project. It demonstrates how to build business applications using the CAP Java SDK providing a book shop web application as an example. The application in this project enables browsing books, managing books, and managing orders.

Outline

Overview
- Demonstrated Features
Getting Started
Code Tour
Get Support
License

Overview

This sample application shows how to conveniently create business applications based on CDS domain models, persisting data with H2, or SAP HANA, and exposing an OData V4 frontend with an SAP Fiori frontend on top.

This sample uses Spring Boot as an application framework. Although a CAP Java application isn’t required to build on Spring Boot, it’s the first choice of framework, as it’s seamlessly integrated.

The domain models are defined using CDS entity definitions.

By default, an in-memory H2 database is used for data persistency. Once productively deployed to SAP Business Technology Platform, SAP HANA can be used.

Services are defined using CDS Service Models. The OData V4 Protocol Adapter translates the CDS service models into corresponding OData schemas and maps the incoming OData requests to the corresponding CDS services.

Although CAP provides generic event handlers to serve most CRUD requests out-of-the-box, it’s possible to add business logic through Custom Event Handlers.

A SAP Fiori UI is added using predefined SAP Fiori elements templates. SAP Fiori annotations add information to the service definitions, on how to render the data.

CAP provides built-in multitenancy support with out-of-the box tenant isolation. The sample application demonstrates usage of MTX sidecar based on streamlined MTX and can be deployed as multitenant application. The deprecated classic MTX setup is shown in the mtx-classic branch for reference.

Demonstrated Features

Framework and Infrastructure related Features:

Application configuration for Spring and CDS using application.yaml
Mocking users for local development
Authentication & Authorization (including user-specific restrictions with @restrict in the Admin Service)
Cloud Foundry Deployment using MTA with XSUAA Service Bindings
Application Router configuration including authentication via the XSUAA Service. See package.json, xs-app.json and xs-security.json
Multitenancy configuration via mta-multi-tenant.yaml, .cdsrc.json, sidecar module
Feature toggles. In CF, features can be toggled by assigning the roles expert or premium-customer to the user.
Messaging configuration and handlers with local messaging and message brokers.
Consumption of Remote services in [srv/external.cds] and [srv/notes-mashup.cds]

Domain Model related Features:

CDS Query Language with a Static CDS Model in the Admin Service
Use of Aspects in the Model Definition such as the managed or cuid Aspect in Books
Input validation using model annotation @assert.format
Data Localization for Books
Use of Media Data in Books and AdminService

Service Model related Features:

Custom event handlers such as the Custom business logic for the Admin Service
Custom actions such as addToOrder in the Admin Service. The Action implementation is in the Admin Service Event Handler
Add annotations for searchable elements in the Admin Service
Localized Messages in the Admin Service Event Handler
role- and instance-based restrictions in AdminService and ReviewService
Use of @cds.persistence.skip in AdminService
Media Data processing in the Admin Service Event Handler

User Interface related Features:

Support for SAP Fiori Elements
SAP Fiori Draft based Editing for Books, Orders and Reviews
SAP Fiori annotations specific for Browse Books, Manage Books, Manage Orders, Manage Reviews and common annotations, which apply to all UI's
UI Annotations for custom actions in the Browse Books and Manage Books UI, including annotations for a button and a popup
Value Help for Books and Authors
Model Localization for English and German language for static texts
Custom File Upload extension which provides a button for uploading CSV files
A simple Swagger UI for the CatalogService API at http://localhost:8080/swagger/index.html

CDS Maven Plugin Features:

Install Node.js in the default version.
Install a configured version of @sap/cds-dk.
Execute arbitrary CDS commands.
Generate Java POJOs for type-safe access to the CDS model.
Clean project from artifacts of the previous build.

Getting Started

The following sections describe how to set up, build, and run the project.

Prerequisites

Make sure you have set up a development environment (that means, you’ve installed the CDS Compiler, Java 21, and Apache Maven) as described here. This sample application requires a Java 21 compatible JDK. We recommend using SapMachine 21.

Clone Build & Run

Clone the project:

git clone https://github.com/SAP-samples/cloud-cap-samples-java.git

Build and run the application:

mvn spring-boot:run

Note

Please note that some IDEs may interfere with their autobuild when launching the application from the CLI using Maven. Therefore, please ensure that no IDEs are running in parallel or launch the application natively from your preferred IDE as described below.

Use the following links in the browser to check if everything works fine:

http://localhost:8080: This should show the automatically generated index page of served paths.
http://localhost:8080/fiori.html: This is the actual bookshop application UI.
http://localhost:8080/swagger/index.html: This is providing a Swagger UI for the CatalogService API.

You'll start with a predefined stock of books as this procedure starts the bookshop application with a CSV-initialized in-memory H2 database.

Two mock users in addition to the default mock users are defined for local development:

User: user, password: user to browse books
User: admin, password: admin to manage books and orders

Using VS Code

VS Code supports the project out-of-the-box, when using the Extension Pack for Java. To launch the application in VS Code navigate to the Application class and click on Run or Debug.

Using Eclipse

Use the following steps to import the project to Eclipse:

Import the project using File > Import > Existing Maven Projects.

Now, you should see the projects bookshop and bookshop-parent in the project/package explorer view.
In Project Explorer, change the property "Package Presentation" from "Flat" to "Hierarchical" for better understanding.

Building and Running

To compile the project, right-click the file pom.xml in the bookshop-parent project root folder and select Run as > Maven build.

In the following dialog, enter the string clean install into the field labeled with "Goals" and click "Run".

Note: This step also compiles the CDS artifacts, thus repeat this once you made changes to the CDS model. This step also generates source files, therefore refresh the "bookshop" project in your IDE.
To run the application, right-click the bookshop project root in the Package Explorer and select Run as > Spring Boot App (make sure you have Spring Tools 4 installed).

This step creates a default Run Configuration named Bookshop - Application and starts the application afterwards. To go on with the next step, stop the application again.
Then, set the default working directory by editing your Run Configuration via Run > Run Configurations > Bookshop - Application. On the tab Arguments change the default Working Directory to:

${workspace_loc:bookshop-parent}

Afterward, click Run. This step starts the applications main method located in src/main/java/my/bookshop/Application.java.

Using IntelliJ Idea (Community and Ultimate)

IntelliJ can handle the project more or less out-of-the-box. Since some of the event handlers in the project rely on the code generated from the CDS model the build path of the project (module) needs to be extended with the folder containing the generated code. In order to add the generated code you need to add the 'gen' folder to the build path:

Right-click the srv/src/gen/java folder, select 'Mark Directory as' and mark it as 'Sources Root'.
Right-click the srv/src/gen/resources folder, select 'Mark Directory as' and mark it as 'Resources Root'.

After the generated code is considered by IntelliJ's build the application can be handled just as any other Spring Boot application in IntelliJ.

Database Setup and Spring Profiles

The application comes with two predefined profiles that determine how to run the application: default, and cloud (see srv/src/main/resources/application.yaml).

The default profile specifies to use an in-memory H2 database. The in-memory database is set up automatically during startup of the application and initialized with some example data from CSV files.
When deploying the application to Cloud Foundry, the CF Java Buildpack automatically configures the cloud Spring profile. This profile doesn’t specify any datasource location. In that case CAP Java can automatically detect SAP HANA service bindings available in the environment.

API_BUSINESS_PARTNER Remote Service and Spring Profiles

The behavior of the API_BUSINESS_PARTNER remote service is controlled using profiles (see srv/src/main/resources/application.yaml):

Using mock data via internal service: When using only the default profile (default when omitting any profile setting), the API_BUSINESS_PARTNER API is mocked as a local service using the mock data.
Using mock data via internal service through OData: With the mocked profile, all requests to the API_BUSINESS_PARTNER service will be routed through HTTP and OData to itself (http://localhost:<port>/api/API_BUSINESS_PARTNER/...). This mode is similar to using a real remote destination, and such helps to prevent issues from differences in local service and remote service behavior.
Using the sandbox environment: You can access data from the SAP API Business Hub sandbox with the sandbox profile. The API key needs to be provided with the environment variable CDS_REMOTE_SERVICES_API_BUSINESS_PARTNER_HTTP_HEADERS_APIKEY or in the respective section in application.yaml. You can retrieve it by clicking on Show API Key on this page after logging in.
Using S/4HANA cloud or on-premise system: With the destination profile, you can access data from a real S/4HANA system. You need to create a destination with name s4-destination and make sure that an instance of XSUAA and destination service are bound to your application. For an on-premise destination, you additionally need to bind the connectivity service and add an additional property URL.headers.sap-client with the S/4HANA client number to your destination.

The profiles sandbox and destination can be combined with the default profile for hybrid testing and with the cloud profile when deployed to the cloud.

Deploy to SAP Business Technology Platform, Cloud Foundry

CAP Java applications can be deployed to the SAP Business Technology Platform either in single tenant or in multitenancy mode. See Multitenancy in CAP Java for more information.

Prerequisites:

Install the Cloud MTA Build Tool: npm install -g mbt.
Install the Cloud Foundry Command Line Interface.
Get an SAP Business Technology Platform account to deploy the services and applications.
Create a SAP HANA Cloud Instance in your SAP Business Technology Platform space.
Ensure you have an entitlement for SAP HANA Schemas & HDI Containers with plan hdi-shared in the same space.
Ensure you have provided an API Key for the sandbox environment as described in the previous section.

Note

Please note that some IDEs may interfere with their autobuild during the MTA build and thus lead to corrupt MTA build results. Therefore, please ensure that no IDEs are running in parallel with your MTA build.

Deploy as Single Tenant Application:

Rename mta-single-tenant.yaml to mta.yaml
Run mbt build
Run cf login
Run cf deploy mta_archives/bookshop_1.0.0.mtar

Deploy as Multitenant Application:

Rename mta-multi-tenant.yaml to mta.yaml
Run mbt build
Run cf login
Run cf deploy mta_archives/bookshop-mt_1.0.0.mtar
Go to another subaccount in your global account, under subscriptions and subscribe to the application you deployed.
Run cf map-route bookshop-mt-app <YOUR DOMAIN> --hostname <SUBSCRIBER TENANT>-<ORG>-<SPACE>-bookshop-mt-app or create and bind the route manually.

Note

Please note that the route length is limited to 63 characters and can easily be exceeded. So keeping the app name and sub-account subdomain as short as possible will help you stay within length.

Before you can access the UI using the (tenant-specific) URL to the bookshop(-mt)-app application, make sure to Setup Authorizations in SAP Business Technology Platform.

Deploy to SAP Business Technology Platform, Kyma Runtime

TIP: You can find more information in the Deploy Your CAP Application on SAP BTP Kyma Runtime tutorial and in the Deploy to Kyma/K8s guide of the CAP documentation.

Preconditions

BTP Subaccount with Kyma Runtime
BTP Subaccount with Cloud Foundry Space
HANA Cloud instance available for your Cloud Foundry space
BTP Entitlements for: HANA HDI Services & Container plan hdi-shared, Launchpad Service plan standard
Container Registry (e.g. Docker Hub)
Command Line Tools: kubectl, kubectl-oidc_login, pack, docker, helm, cf
Logged into Kyma Runtime (with kubectl CLI), Cloud Foundry space (with cf CLI) and Container Registry (with docker login)
@sap/cds-dk >= 6.6.0

Add Deployment Files

CAP tooling provides you a Helm chart for deployment to Kyma.

For single tenant deployment, replace the requires section in .cdsrc.json with:

    "requires": {
        "auth": {
            "kind": "xsuaa"
        },
        "approuter": {
            "kind": "cloudfoundry"
        },
        "db": {
            "kind": "hana-cloud"
        }
    },

In addition remove "profile": "with-mtx-sidecar" from .cdsrc.json and delete the mtx folder in root.

For multi tenant deployment, replace the requires section in .cdsrc.json with:

    "requires": {
        "multitenancy": true,
        "extensibility": true,
        "toggles": true,
        "auth": {
            "kind": "xsuaa"
        },
        "approuter": {
            "kind": "cloudfoundry"
        }
    },

Add the CAP Helm chart with the required features to this project:

cds add helm

Use API_BUSSINESS_PARTNER Remote Service (optional, single tenant only)

You can try the API_BUSINESS_PARTNER service with a real S/4HANA system with the following configuration:

Create either an on-premise or cloud destination in your subaccount.
Add configuration required for the destination service by executing the following command.
```
cds add destination
```

Set the profiles cloud and destination active in your values.yaml file:

srv:
  ...
  env:
    SPRING_PROFILES_ACTIVE: cloud,destination

For on-premise only: Add the connectivity service to your Helm chart:
```
cds add connectivity
```
Note: cds add helm will not add configuration required to create a Connectivity Service Instance. This Service Instance should be created by the Kyma Cluster Administrator. For more information regarding configuration of Connectivity Instance, please check the documentation.

See also: API_BUSINESS_PARTNER Remote Service and Spring Profiles

Prepare Kubernetes Namespace

Create container registry secret

Create a secret container-registry with credentials to access the container registry:

bash ./scripts/create-container-registry-secret.sh

The Docker Server is the full qualified hostname of your container registry.

Create a HDI container / Service Manager Instance and a Secret

This step is only required if you're using a BTP Trial account. If you're using a production or a free tier account then you can create HDI Container from Kyma directly by adding a mapping to your Kyma namespace in your HANA Cloud Instance and skip this step.

Single Tenant

bash ./scripts/create-db-secret.sh bookshop-db

It will create a HDI container bookshop-db instance on your currently targeted Cloud Foundry space and a secret bookshop-db with the credentials in your current Kubernetes namespace.

Make the following changes to your chart/values.yaml.

srv:
  bindings:
    db:
-     serviceInstanceName: hana
+     fromSecret: bookshop-db
...

hana-deployer:
  bindings:
    hana:
-     serviceInstanceName: hana
+     fromSecret: bookshop-db

...
- hana:
-   serviceOfferingName: hana
-   servicePlanName: hdi-shared

Make the following changes to your chart/Chart.yaml.

dependencies:
  ...
-  - name: service-instance
-    alias: hana
-    version: ">0.0.0"
  ...

Multi Tenant

bash ./scripts/create-sm-secret.sh bookshop-sm

It will create a Service Manager bookshop-sm instance on your currently targeted Cloud Foundry space and a secret bookshop-sm with the credentials in your current Kubernetes namespace.

Make the following changes to your chart/values.yaml.

srv:
  bindings:
    service-manager:
-     serviceInstanceName: service-manager
+     fromSecret: bookshop-sm
...

sidecar:
  bindings:
    service-manager:
-     serviceInstanceName: service-manager
+     fromSecret: bookshop-sm

...
- service-manager:
-   serviceOfferingName: service-manager
-   servicePlanName: container

Make the following changes to your chart/Chart.yaml.

dependencies:
  ...
-  - name: service-instance
-    alias: service-manager
-    version: ">0.0.0"
  ...

Build

cds build --production

Build image for CAP service:

mvn clean package -DskipTests=true

pack build ${YOUR_CONTAINER_REGISTRY:?}/bookshop-srv \
        --path srv/target/*-exec.jar \
        --buildpack gcr.io/paketo-buildpacks/sap-machine \
        --buildpack gcr.io/paketo-buildpacks/java \
        --builder paketobuildpacks/builder-jammy-base \
        --env SPRING_PROFILES_ACTIVE=cloud \
        --env BP_JVM_VERSION=17

(Replace ${YOUR_CONTAINER_REGISTRY:?} with the full-qualified hostname of your container registry)

Build Approuter Image:

pack build ${YOUR_CONTAINER_REGISTRY:?}/bookshop-approuter \
     --path app \
     --buildpack gcr.io/paketo-buildpacks/nodejs \
     --builder paketobuildpacks/builder-jammy-base \
     --env BP_NODE_RUN_SCRIPTS=""

Build database deployer image (single tenant only):

pack build ${YOUR_CONTAINER_REGISTRY:?}/bookshop-hana-deployer \
     --path db \
     --buildpack gcr.io/paketo-buildpacks/nodejs \
     --builder paketobuildpacks/builder-jammy-base \
     --env BP_NODE_RUN_SCRIPTS=""

Build sidecar image (multi tenant only):

pack build ${YOUR_CONTAINER_REGISTRY:?}/bookshop-sidecar \
     --path mtx/sidecar/gen \
     --buildpack gcr.io/paketo-buildpacks/nodejs \
     --builder paketobuildpacks/builder-jammy-base \
     --env BP_NODE_RUN_SCRIPTS=""

Push container images

You can push all the container images to your container registry, using:

docker push ${YOUR_CONTAINER_REGISTRY:?}/bookshop-srv

docker push ${YOUR_CONTAINER_REGISTRY:?}/bookshop-approuter

Single Tenant

docker push ${YOUR_CONTAINER_REGISTRY:?}/bookshop-hana-deployer

Multi Tenant

docker push ${YOUR_CONTAINER_REGISTRY:?}/bookshop-sidecar

Configuration

Make the following changes in the chart/values.yaml file.

Change value of global.domain key to your cluster domain.
Replace <your-cluster-domain> in xsuaa.parameters.oauth2-configuration.redirect-uris with your cluster domain.
Replace <your-container-registry> with your container registry.
Make the following change to add backend destinations required by Approuter.

-  backendDestinations: {}
+  backendDestinations:
+     backend:
+       service: srv
+     mtx-api:
+       service: srv

Add your image registry secret created in Create container registry secret step.

global:
  domain: null
-  imagePullSecret: {}
+  imagePullSecret:
+    name: container-registry

If the application is deployed multiple times in the same cluster, make sure to adapt the values of xsappname and appName under saasRegistryParameters in values/Chart.yaml

Deployment

Deploy the helm chart using the following command:

Single Tenant

helm install bookshop ./chart --set-file xsuaa.jsonParameters=xs-security.json

Before you can access the UI you should make sure to Setup Authorizations in SAP Business Technology Platform.

Click on the approuter url logged by the helm install to access the UI.

Multi Tenant

helm install bookshop ./chart --set-file xsuaa.jsonParameters=xs-security-mt.json

In case of multi tenant, you'll have to subscribe to the application from a different subaccount. You can follow the steps mentioned here to access the application.

Setup Authorizations in SAP Business Technology Platform

To access services and UIs that require specific authorizations (e.g. admin) you need to assign a corresponding role and role collections to your user in SAP BTP Cockpit.

For single-tenant applications open the subaccount where you deployed the bookshop application to. For multitenant applications open the subaccount where you subscribed to the bookshop application.
Navigate to Security -> Roles
Create a role with name bookshop-admin based on the admin role template of the bookshop application:
1. Enter a Business Partner ID of your S/4 system as value for the businessPartner attribute. When using the sandbox environment use 10401010.
Navigate to Security -> Role Collections
Create a new role collection bookshop-admin:
1. Assign the bookshop-admin role to this role collection
2. Assign the role collection to your user

Code Tour

Take the guided tour in VS Code through our CAP Samples for Java and learn which CAP features are showcased by the different parts of the repository. Just install the CodeTour extension for VS Code.

Get Support

In case you have a question, find a bug, or otherwise need support, please use our community. See the documentation at https://cap.cloud.sap for more details about CAP.

Name		Name	Last commit message	Last commit date
Latest commit History 283 Commits
.github/workflows		.github/workflows
.reuse		.reuse
.tours		.tours
LICENSES		LICENSES
app		app
assets		assets
db		db
fts/isbn		fts/isbn
integration-tests		integration-tests
mtx/sidecar		mtx/sidecar
scripts		scripts
srv		srv
.cdsprettier.json		.cdsprettier.json
.cdsrc.json		.cdsrc.json
.gitignore		.gitignore
LICENSE		LICENSE
README.md		README.md
mta-multi-tenant.yaml		mta-multi-tenant.yaml
mta-single-tenant.yaml		mta-single-tenant.yaml
pom.xml		pom.xml
requests.http		requests.http
xs-security-mt.json		xs-security-mt.json
xs-security.json		xs-security.json

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etimr/cloud-cap-samples-java

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Welcome to CAP Samples for Java

Outline

Overview

Demonstrated Features

Getting Started

Prerequisites

Clone Build & Run

Using VS Code

Using Eclipse

Building and Running

Using IntelliJ Idea (Community and Ultimate)

Database Setup and Spring Profiles

API_BUSINESS_PARTNER Remote Service and Spring Profiles

Deploy to SAP Business Technology Platform, Cloud Foundry

Deploy to SAP Business Technology Platform, Kyma Runtime

Preconditions

Add Deployment Files

Use API_BUSSINESS_PARTNER Remote Service (optional, single tenant only)

Prepare Kubernetes Namespace

Create container registry secret

Create a HDI container / Service Manager Instance and a Secret

Single Tenant

Multi Tenant

Build

Push container images

Single Tenant

Multi Tenant

Configuration

Deployment

Single Tenant

Multi Tenant

Setup Authorizations in SAP Business Technology Platform

Code Tour

Get Support

License

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