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The following steps will explain how to create the very first HelloWorld example on SCP Neo using the SAP S/4HANA Cloud SDK. If you want to follow this tutorial, we highly recommend checking out the first part of this blog series. You will not need any additional software as the server will run on your local machine.

Note: This post is part of a series. For a complete overview visit the SAP S/4HANA Cloud SDK Overview.

 

Goal of this blog post

The tutorial will show you the first steps when developing applications for the SCP Neo using the SAP S/4HANA Cloud SDK. To be precise, we will cover the following steps:

  1. Generate a project stub using a Maven Archetype
  2. Understand the project structure and its artifacts
  3. Implement and understand the Hello World Servlet
  4. Implement and understand the integration test
  5. Deployment

 

Generate Project from Archetype

Since you have already installed Maven, you can use it to generate a project stub from the SAP S/4HANA Cloud SDK Maven archetype. Just use your console (e.g. IDE, OS, navigate to a parent directory for your project and run the following command.

mvn archetype:generate -DarchetypeGroupId=com.sap.cloud.sdk.archetypes -DarchetypeArtifactId=scp-neo-javaee6 -DarchetypeVersion=1.0.0-SNAPSHOT

Once the generation process is started, Maven will ask you for the usual module parameters:

groupId an identifier representing your group, company or organization (e.g. com.mycompany.cloud)
artifactId an identifier for your application (e.g. firstapp)
version the version of your application (e.g. 1.0-SNAPSHOT)
package the name of the top-level package your source code will reside in (typically equal to your groupId, e.g. com.mycompany.cloud)

After the required values are provided, Maven will generate the new project from the Cloud SDK archetype:

For the tutorial we suppose you have chosen “firstapp” as artifactId / project name.

Now you can work with it just like any other Maven project.

cd /path/to/firstapp
mvn clean install

Understand the project structure and its artifacts

Once the Maven project is generated, you can open your favorite IDE and load the project as “Maven Project”. After importing the project into your IDE, the overall structure will look like this:

The first thing you will notice, is the directories firstapp-app and firstapp-integration-tests. These are Maven sub-modules and they serve different aspects of your code testing environment. The following separation of application and test modules makes it possible to run integrations test without deploying.

  • application contains the source code and configuration of your actual web application
    src/main/java Here goes your production code, nothing else. As you can see, there’s already the HelloWorldServlet, which we will look at in more detail soon.
    src/main/resources Anything that you require in your production code but is no compilable code goes here (typically things like API definition files for RAML or OpenAPI, Database Migration Files for Flyway or Liquibase)
    src/main/webapp contains the deployment descriptor for your web application – the infamous web.xml
    src/test/java This is the place for your automated tests.
    src/test/resources Tests may also require additional resources to work properly such as configuration files. This is their place.
    pom.xml This is your project management file for Maven where you can maintain other open source dependencies or use plugins that ease your build Environment.
  • integration-tests contains the integration tests for your application. Its structure is similar toapplication.
    src/test/java Here you can put all your integration tests. As you can see, there’s already the HelloWorldServiceTest corresponding to the HelloWorldServlet.
    src/test/resources Here go all the resources needed for the integration tests to run.

This separation of test modules makes it possible to just run integrations test without deploying, as well as deploying the application without running time consuming integration tests. Unit tests will be kept publicly inside the application module. For that topic we highly recommend the articles and educational videos from Martin Fowler. For a start we advice reading his post about Unit Tests.

Integration tests

During development it becomes important to test newly implemented code to external services, i.e. logic running in a distributed environment. This is where integration tests are an important tool to ensure correctness and stability over the whole internal and external deployment. Since these integration tests may contain confidential information, like business logic and test access tokens, it can be helpful to maintain its operation inside a dedicated Maven sub module. That way the application can be shipped without integration tests and their dependency.

Implement and understand the Hello World Servlet

Now that you understand the project structure, take a closer look at the HelloWorldServlet.java

package com.sap.cloud.sdk.tutorial;
 
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
 
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
 
@WebServlet("/hello-servlet")
public class HelloWorldServlet extends HttpServlet
{
    private static final long serialVersionUID = 1L;
    private static final Logger logger = LoggerFactory.getLogger(HelloWorldServlet.class);
 
    @Override
    protected void doGet( final HttpServletRequest request, final HttpServletResponse response )
        throws ServletException, IOException
    {
        logger.info("I am running!");
        response.getWriter().write("Hello World!");
    }
}

The HelloWorldServlet extends HttpServlet, so this will be a HTTP endpoint that we can visit. We map this endpoint to the /hello-servlet route using @WebServlet("/hello-servlet").

By overriding the function doGet, we define what happens when a client performs an HTTP GET request on the /hello-servlet route. in this case we simply write a response containing “Hello World!”.

Implement and understand the integration test

Let’s take a look into the integration test project. It already contains a test for our simple HelloWorldServlet:

package com.sap.cloud.sdk.tutorial;
 
import com.jayway.restassured.RestAssured;
import org.jboss.arquillian.container.test.api.Deployment;
import org.jboss.arquillian.junit.Arquillian;
import org.jboss.arquillian.test.api.ArquillianResource;
import org.jboss.shrinkwrap.api.spec.WebArchive;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.runner.RunWith;
import java.net.URL;
 
import com.sap.cloud.sdk.tutorial.HelloWorldServlet;
import com.sap.cloud.sdk.testutil.MockUtil;
 
import static com.jayway.restassured.RestAssured.given;
import static org.assertj.core.api.Assertions.assertThat;
 
@RunWith( Arquillian.class )
public class HelloWorldServiceTest
{
    private static final MockUtil mockUtil = new MockUtil();
 
    @ArquillianResource
    private URL baseUrl;
 
    @Deployment
    public static WebArchive createDeployment()
    {
        return TestUtil.createDeployment(HelloWorldServlet.class);
    }
 
    @BeforeClass
    public static void beforeClass()
    {
        mockUtil.mockDefaults();
    }
 
    @Before
    public void before()
    {
        RestAssured.baseURI = baseUrl.toExternalForm();
    }
 
    @Test
    public void testService()
    {
        final String body = given().get("/hello-servlet").body().asString();
        assertThat(body).isEqualToIgnoringCase("Hello World!");
    }
}

As you can see, HelloWorldServiceTest uses JUnit to define the test.

  • It declares BeforeClass and Deployment for the general test setup.
  • The MockUtil provides easy access to mocked backend systems, e.g. preconfigured ERP connections for the test cases.
  • A WebArchive is deployed as a test run setup, including predefined additional classes, here: HelloWorldServlet.class
  • The integration test features RestAssured to easily run WebService calls over HTTP. Later you will see the advantages of having this library on hand, when dealing with more sophisticated examples. Here it runs an assertion test on the result of a GET request to the local /hello-servlet route.

Deployment

It is time to finally deploy the application.

Local deployment

To run all required Maven goals, you can use the following commands in the project root path, i.e. parent module:

mvn clean install
mvn scp:clean scp:push -pl application

The first command will cascade the goal execution of clean and install to both Maven sub modules. It will break in case of any compilation errors or test failures.

The second command will run a cleanup and startup for the SCP Neo application. The -pl argument defines the project location in which the Maven goals are being executed. If there is already a previously started instance of the application running, the goal scp:clean will try to stop it on localhost:8080 and will remove the cached server files of the application. scp:push will start the application on localhost:8080. The web server is started as background process and will take additional seconds to initialize.

Once a couple of seconds have passed, you can open a browser and go to http://localhost:8080/hello

  • You will be greeted with a login screen.
  • Enter test / test

 

Hello world!

That’s it.

When you are done and want to close the local SCP deployment, please use the scp:clean command for the application project. It will close any connection and stop the server.

mvn scp:clean -pl application

 


 

Remote deployment

As a requirement make sure to have the Neo CLI available.

In case you are missing this tool, feel free to download it. A traditional installation is not required:

The Neo CLI comes packaged with the SAP Cloud Platform Neo Environment SDK

  1. Go to https://tools.hana.ondemand.com/#cloud
  2. Download and unzip the latest neo-javaee6-wp-sdk-######.zip alias “Java EE 6 Web Profile”
  3. Go into the directory “tools” and find the neo.bat (Windows) or neo.sh (Mac/Linux)

Please consider reading the readme.txt file in case you use a proxy server for connecting to the host. Also we recommend adding this tools directory to your PATH variable, in order to run its executables from any location.

Once you open your Neo platform website, you will see your account name as well as the hostname of the service.

The hostname is usually depending on your general location:

Europe (Rot) – Trial hanatrial.ondemand.com
Europe (Rot) eu1.hana.ondemand.com
US West (Chandler) us2.hana.ondemand.com
US East (Ashburn) us1.hana.ondemand.com
US East (Sterling) us3.hana.ondemand.com
Japan (Tokyo) jp1.hana.ondemand.com
China (Shanghai) cn1.hana.ondemand.com
Australia (Sydney) ap1.hana.ondemand.com

 

  • Now run the required Maven goals in the project root path and use neo to deploy the packaged application to the remote Neo instance.
    mvn clean install
    /path/to/neo deploy --host HOST --account ACCOUNT --user USER --application firstapp --source firstapp-app/target/firstapp-app-1.0-SNAPSHOT.war
    /path/to/neo start --host HOST --account ACCOUNT --user USER --application firstapp

  • You can check the status of your deployment with the status command:
    /path/to/neo status --host HOST --account ACCOUNT --user USER --application firstapp

  • If you want to list all running applications use the list-applications command:
    /path/to/neo list-applications --host HOST --account ACCOUNT --user USER

  • On the Neo website you will find the corresponding URL, where your application is reachable.Hello world!

That’s it.

To find additional Neo commands, e.g. for stopping and undeploying applications, please take a look into the official lists of Neo Console Client Commands.

 


Appendix

Hint: Force application shutdown

In case the Maven scp:clean goal does not shutdown the application background process, even after the second execution, we recommend terminating it by hand. First you need to detemine the process id by the public port. Then terminate the process.

# Windows
netstat -o -n -a | findstr 0.0:8003
taskkill /F /PID <PID>
# OSX
lsof -i :8003
kill -9 <PID>
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