Create a Hello World Multitarget Application

You define the entities that have to be deployed, namely modules and resources related to other modules, in the MTA deployment descriptor. This is a YAML file that defines the contract between you as a deployable artifact provider and the SAP BTP as a deployer tool. Initially, you have to describe the metadata required for the deployment.

1. Create an empty text file and name it mtad.yaml.
2. Using a text editor, enter the following data in the file:

Strictly adhere to the correct indentations when working with YAML files, and do not use the tabulator character.

``` YAML
_schema-version: '3.1'

parameters:
   hcp-deployer-version: '1.1.0'

ID: com.example.demo.basic
version: 0.1.0
```

The example above instructs the SAP BTP to:

* Validate the Multitarget Application against the MTA specification version `3.1`
* Use deploy features specific to the SAP BTP marked as version `1.0`
* Deploy the Multitarget Application as a Solution with ID `com.example.demo.basic`
* Consider the Multitarget Application version as a version `0.1.0`

1. Create the module that describes the Java application. In the mtad.yaml, add the following data:

   YAML

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   modules:
       -name: example-java-app
        type: com.sap.java
        requires:
          - name: db-binding
        parameters:
          name: example
          jvm-arguments: -server
          java-version: JRE 7
          runtime: neo-java-web
          runtime-version: 1
   

   The example above instructs the SAP BTP to:

   • Deploy a Java application with a specific runtime, Java version, and runtime arguments
   • Require a MTA resource called db-bindings, where you describe your binding data

2. Describe the database binding ID and the database credentials the Java application has to use by adding the following to the mtad.yaml:

   YAML

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   resources:
     - name: db-binding
       type: com.sap.hcp.persistence
       parameters:
         id:
   

   The example above instructs the SAP BTP to create a database binding during the deployment process.

   At this point of the procedure, no database ID or credentials for your database binding have been added. The reason for this is that all the content of the mtad.yaml so far is a target-platform independent, meaning that the same mtad.yaml could be deployed to multiple SAP BTP subaccounts.

   The information about your database ID and credentials are, however, subaccount-specific. To keep the mtad.yaml target platform independent, you have to create an MTA extension descriptor. This file is used in addition to your primary descriptor file, and contains data that is account-specific.

Security-sensitive data, for example database credentials, should be always deployed using an MTA extension descriptor, so that this data is encrypted.

1. Create an empty text file and name it dev.mtaext.

2. Using a text editor, enter the following data in the file:

   YAML

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   _schema-version: '3.1'
   ID: com.example.demo.basic.config
   extends: com.example.demo.basic
   parameters:
     title: Basic Solution
     description: This is a sample of a basic Solution.
   resources:
   - name: db-binding
     parameters:
       id: dbalias
       user-id: myuser
       password : mypassword
   

The example above instructs the SAP BTP to:

• Extend the com.example.demo.basic MTA deployment descriptor with the com.example.demo.basic.config MTA extension descriptor
• Define the title and description for the target solution that will be visible in the SAP BTP
• Extend the db-binding resource and define within the following parameters:
  • Alias of the database
  • User for the database schema that you own
  • Password for the database schema that you own

  At this point of the procedure, the MTA deployment descriptor, MTA extension descriptor, and the Java application .war files are compiled. You can now package your Multitarget Application archive and deploy it to the SAP BTP.

  The MTA archive contains all entities that have to be deployed. It also contains a manifest file, which links the modules and resources described into the MTA deployment descriptor file using their location in the archive. Using this data, the SAP BTP deploys the Multitarget Application archive as a solution.

1. Create an empty text file and name it MANIFEST.MF. Explicitly use upper-case letters.

2. Using a text editor, enter the following data in the file:

   Manifest-Version: 1.0
   Created-By: example.com
   
   Name: example.war
   Content-Type: application/zip
   MTA-Module: example-java-app
   

   The example above instructs the SAP BTP to link the module example-java-app to the archive example.war.

   CAUTION

   Make sure that the MANIFEST.MF is compliant to the JAR file specification.

MTA archives are compliant to the JAR file specification. This allows you to use commonly available tools for creating, modifying, and signing such archives. For the sake of the tutorial, we assume that you have a root directory named / where you place all the parts of the Multitarget Application before creating the archive.

1. Create a folder called META-INF in the root directory.
2. Place the mtad.yaml and the MANIFEST.MF files inside the META-INF directory.
3. Place the example.war archive inside the root directory.

The MTA extension descriptor file is deployed separately from the MTA archive.

The root directory should now be structured as follows:

```
/example.war
/META-INF
/META-INF/mtad.yaml
/META-INF/MANIFEST.MF
```

1. Archive the content of the root directory in an .mtar format using an archiving tool capable of producing a JAR archive.

After you have created your Multitarget Application archive, you are ready to deploy it into the SAP BTP as a solution. To deploy the archive, proceed as described in Deploy a Standard Solution.