SAP HANA XS Advanced, Creating an HTML5 Module

What is a Multi-Target Application?: The XS Advanced application platform is based on >Cloud Foundry, an open-source platform that provides a layer of abstraction between your application and the underlying infrastructure. This is useful because it allows you to deploy the same application in different cloud providers. Cloud Foundry allows for a micro-service approach. A Multi-Target Application allows you to bundle all the different micro-services conforming your business application into the same lifecycle. For more information about multi-target applications (MTA), refer to this blog post.

Begin by right-clicking on your project and then choosing New -> HTML5 Module

Name the module web. Press Next to see the confirmation. Then press Finish.

You will notice a new folder under the project folder. SAP Web IDE has automatically created the appropriate folder structure for you. Open the resources folder to answer the validation below.

Before you can use the UAA service, you need to create a instance for your application.

If you have installed the XS Advanced administration cockpit (included by default in SAP HANA, express edition SPS03 or higher), you can use the graphical interface to create an instance of the UAA service.

The default URL for the cockpit in HANA express is https://hxehost:51036, you can find out using the XS CLI as below:

Open the XSA cockpit with a different browser or alternate between private/incognito and normal mode. Log in with XSA_ADMIN (or an appropriate user) if prompted. Click on the organization you are using for development:

Then continue to select the same space you have chosen for your MTA project

Expand the Services menu, select Service Marketplace and click Authorization and Trust management:

Use Instances and press New Instance. Choose service plan space

When prompted for an optional .json file, click next. Use UAA-service as the name of the Instance

Click Finish and you will see your instance is created.

Alternatively, if you do not have the XS Advanced Cockpit in your server, you can use the Command Line Interface:

- This can be downloaded from the SAP HANA Developer Edition directly, using the Download Manager and choosing "Clients" from the [SAP HANA, Express Edition, getting started](https://www.sap.com/developer/topics/sap-hana-express.html) or via the [SAP Service Marketplace](https://websmp208.sap-ag.de/~SAPIDP/002006825000000234912001E)

```
xs login -a http://<hostname>:3XX30 -o HANAExpress -s development -u XSA_ADMIN
```

If you are not using HANA Express, change the organization (`HANAExpress`), space (`development`) and user (`XSA_DEV`) accordingly. The API endpoint may also be different.

The space has to match the space that was setup in the Project Settings. You can check it by right-clicking on the repository folder and opening "Project Settings"


![Command line XS Login](5.png)
To create the UAA service issue the following command:

```
xs create-service xsuaa space APP_UAA

```

![Command line UAA](6.png)

The User Account and Authentication service validates users and their roles and provides them with an authentication token. You can find more information on the UAA service in the developer guide.

Before you can establish a dependency between your HTML5 module and the UAA service instance you created in the previous step, you need to list the UAA service instance as a resource in your applications. Open the mta.yaml file in graphical mode and got to the resources tab. Create a new resource using the + Sign

Fill in the name, choose com.sap.xs.uaa-space from the search help and add the following key-value pairs to the parameters: config-path and ./xs-security.json.

Click Modules to add the dependency to the UAA service in the web module

What is this mta.yaml file for?
We have so far created a Multi Target Application, that is, an application that will contain different modules, such as an HTML5 module and some database artifacts within a HANA Database Module. This file is a design-time descriptor, that will be used by the platform to create a deployment descriptor. This file contains information related to the application (ID, version, description) as well as resources, modules and parameters that will be deployed and required at runtime.

And click on Save

Open the Code Editor tab in the bottom to see the actual contents of the mta.yaml file.

The web folder in your project contains the resources that will be served out by this HTML5 module. This HTML5 module manages all HTML/client side UI resources (in the resources folder) and performs the task of reverse proxy for all other internal services, like a application router. This way you have a single HTTP endpoint and avoid any CORS issues. AMong other files, the Basic HTML5 Module wizard created a file called xs-app.json.

In this file you can map the routes to destinations you defined in the mta.yaml. We can also set authentication and other options. Go ahead and change the authenticationMethod to route in the xs-app.json file.

{
	"welcomeFile": "index.html",
	"authenticationMethod": "route",
	"routes": [ ]
}

You will learn how to add routes to backend modules in the next tutorials. You can check this post to learn more about how this works.

Your initial development is done and you are ready to deploy your application onto the XS Advanced server. Right-click on the project and press Build.

And check the results in the log.

Click on the web folder and click on Run. This will open a new browser tab to the default page of this web service.

The console will be updated with the status of the service. Notice there is a logs URL that will be of use if something goes wrong.

Did you get a red cross and an error in the logs saying the UAA service has not been found? The name of the service in the yaml definition needs to match the name of the service you created. The application and the service need to be in the same space too.

A new tab will open and you will see the default Hello World button has been placed for you: