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Create a Cloud Foundry or XS Advanced App that Queries SAP HANA

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Create a Cloud Foundry or XS Advanced App that Queries SAP HANA
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Create a Cloud Foundry or XS Advanced App that Queries SAP HANA

March 22, 2021
Created by
January 12, 2021
Create a Node.js app that queries SAP HANA and can be run in Cloud Foundry or XS Advanced.

You will learn

  • How to use the command line interface (CLI) to deploy a Node.js app to Cloud Foundry or XS advanced
  • How to view the logs and enable tracing in the deployed app
  • How to connect from a Node.js app running in Cloud Foundry to an on-premise SAP HANA instance through the Cloud Connector
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Prerequisites

  • You have completed the first 4 tutorials in this mission

In the previous tutorials, applications that queried SAP HANA were run on a local machine. In this tutorial, a simple application will be run within the SAP BTP which uses Cloud Foundry or within the SAP HANA, express edition which uses XS advanced (and is also based on Cloud Foundry).

For additional details, consult The XS Advanced Programming Model. For a more complete example, see the Node.js topics in week 3 of Software Development on SAP HANA.


Step 1: Get started with the Command Line Interface (CLI)

The command line interface (CLI) for Cloud Foundry is named cf while the CLI used for apps running in SAP HANA, express edition is named xs.

  1. Check to see if you have the CLI installed and verify the version.

    cf -v
    
    cf cli version

    To install the CLI, see Installing the CLI and Installing the cf CLI.

    xs -v
    
    xs cli version

    The installer for xs can be downloaded from SAP Software Downloads under SAP HANA PLATFORM EDITION | SAP HANA PLATFORM EDITION 2.0 | XS RUNTIME 1.

  2. Access help by running the following:

    cf help
    cf help login
    
    xs help
    xs help login
    
  3. Log in to the Cloud Foundry or XS advanced.

    cf login
    
    cf login

    If you are an SAP employee, you may need to enter your password plus a two-factor authentication passcode.

    The API URL, if requested, can be found in the SAP BTP cockpit.

    api URL

    .

    xs login
    
    xs login

    The API URL, if requested, can be verified in the XSA is up app.

    xsa running
  4. Additional examples are shown below to view the target information, running services, and deployed apps.

    cf target
    cf services
    cf apps
    cf buildpacks
    
    xs target
    xs services
    xs apps
    xs buildpacks
    
    services

    Additional details can be found at Getting Started with the cf CLI and Get Started with the XS CLI Client.

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Step 2: Create Node.js app that queries SAP HANA
  1. Create a folder named nodeCF\nodeQueryCF and enter the newly created directory.

    mkdir %HOMEPATH%\HANAClientsTutorial\nodeCF\nodeQueryCF
    cd %HOMEPATH%\HANAClientsTutorial\nodeCF\nodeQueryCF
    
    mkdir $HOME/HANAClientsTutorial/nodeCF/nodeQueryCF
    cd $HOME/HANAClientsTutorial/nodeCF/nodeQueryCF
    
  2. Initialize the project, install express, and @sap/hana-client from NPM.

    npm init -y
    npm install express
    npm install @sap/hana-client
    
  3. Open a file named server.js in an editor.

    notepad server.js
    
    pico server.js
    
  4. Add the code below to server.js.

    var express = require('express');
    var hana = require('@sap/hana-client');
    var app = express();
    
    app.get('/', function (req, res) {
        res.send('Hello World');
    })
    
    app.get('/Customers', function (req, res) {
        var connOptions = {
            serverNode: 'XXXXXX.hana.trial-XXXXX.hanacloud.ondemand.com:443',
            //serverNode: 'linux-bj72:39015',
            UID: 'USER1',
            PWD: 'Password1'
            //traceFile: 'stdout',
            //traceOptions: 'sql=warning'
        };
    
      var connection = hana.createConnection();
      connection.connect(connOptions, function(err) {
          if (err) {
              return console.error(err);
          }
          var sql = 'select * from HOTEL.CUSTOMER;';
          var rows = connection.exec(sql, function(err, rows) {
              if (err) {
                  return console.error(err);
              }
              console.log(rows);
              res.send(rows);
              connection.disconnect(function(err) {
                  if (err) {
                      return console.error(err);
                  }   
              });
          });
      });
    })
    
    const port = process.env.PORT || 3000;
    var server = app.listen(port, function () {
        var host = server.address().address
        var port = server.address().port
        console.log("Example app listening at http://%s:%s", host, port)
    })
    

    Update the values for host and port.

  5. Run and test the app locally.

    node server.js
    
    running locally
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Step 3: Deploy and test in SAP BTP or XS Advanced
  1. Create a deployment descriptor.

    cd ..
    notepad manifest.yml
    
    cd ..
    pico manifest.yml
    

    Add the code below to manifest.yml.

    ---
    applications:
    - name: nodeQueryCF
      random-route: true
      type: nodejs
      path: nodeQueryCF
      command: node server.js
      memory: 128M
    

    For additional details, consult App Manifest Attribute Reference.

  2. Deploy the app to Cloud Foundry or XS advanced.

    cf push
    
    push result

    Notice above the URL to open the app was generated as the manifest.yml contained the random-route setting.

    xs push
    

    .
    push result

    Alternatively, the URL of the app can be found by running the following command:

    cf app nodeQueryCF
    
    xs app nodeQueryCF
    
  3. Test the app.

    cf app

    .

    xs app

For additional details see:

Developing Node.js in the Cloud Foundry Environment

Tutorial: Setting up your JavaScript Application in XS Advanced

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Step 4: Additional commands
  1. The app can be stopped and started with the below commands:

    cf stop nodeQueryCF
    cf start nodeQueryCF
    
  2. The applications lifecycle events can be seen with the below command:

    cf events nodeQueryCF
    
    events
  3. The logs of the application can be seen with the below command:

    cf logs --recent nodeQueryCF
    

    The following command will show the tail of the log.

    cf logs nodeQueryCF
    
  4. As of version 2.7, the SAP HANA client interfaces can output trace information to stdout or stderr.

    cf set-env nodeQueryCF HDB_SQLDBC_TRACEFILE stdout
    cf set-env nodeQueryCF HDB_SQLDBC_TRACEOPTS SQL=WARN
    cf restage nodeQueryCF
    cf env nodeQueryCF
    cf logs nodeQueryCF
    

    Alternatively, the trace settings can be specified in the application code.

    Refresh the browser and notice that the trace information can now be seen.

    trace
  5. The deployed app can also be managed in the associated cockpit.

    SAP BTP Cockpit

    SAP BTP cockpit

    Details of the application nodeQueryCF

    SAP BTP cockpit

    SAP HANA XS Advanced Cockpit

    XS advanced cockpit

    Note that the number of running instances can be scaled if needed.

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Step 5: Connect from the Node.js app running in the cloud to an on-premise database (optional)

The Cloud Connector enables communication from the SAP BTP running in the public internet to securely connect to a configured on-premise system such as SAP HANA, express edition. The following steps demonstrate how to do this with the previously deployed app nodeQueryCF.

  1. Follow step 3 at Access Remote Sources with SAP HANA Database Explorer to install and configure the Cloud Connector.

  2. In the project created in step 2, perform the following steps to bind a connectivity service instance to the application.

    • Navigate to Service Bindings and choose Bind Service.

      bind service
    • Add the Connectivity service.

      connectivity service
    • Provide an instance name such as MyConnectivityService.

      connectivity service
    • Examine the values of the connectivity service. In particular, the indicated values below are used for the proxyPort and proxyHostname values in the server.js file and will be to access the proxy service which enables communication with the cloud connector.

      connectivity service
  3. Add the service name to the project’s manifest.yml.

    cd %HOMEPATH%\HANAClientsTutorial\nodeCF
    notepad manifest.yml
    
    cd $HOME/HANAClientsTutorial/nodeCF
    pico manifest.yml
    
      services:
      - MyConnectivityService
    
  4. Make a backup of the server.js file and add the node module axios which is promise based HTTP client and is used to fetch a JWT token. For further details see SAP Cloud Platform: How to call – on-Premise System – from Node.js app – via Cloud Connector.

    cd nodeQueryCF
    copy server.js server.js.bak
    npm install axios
    
    cd nodeQueryCF
    cp server.js server.js.bak
    npm install axios
    
  5. Open the file named server.js in an editor and replace its contents.

    notepad server.js
    
    pico server.js
    
    var axios = require('axios');
    var express = require('express');
    var hana = require('@sap/hana-client');
    var app = express();
    
    const VCAP_SERVICES = JSON.parse(process.env.VCAP_SERVICES);
    const conSrvCred = VCAP_SERVICES.connectivity[0].credentials;
    
    app.get('/', function (req, res) {
        res.send('Hello World');
    })
    
    app.get('/Customers', async function (req, res) {
        const connJwtToken = await _fetchJwtToken(conSrvCred.token_service_url, conSrvCred.clientid, conSrvCred.clientsecret);
    
        var connOptions = {
            serverNode: 'v-linux-bj72:39015', // Virtual host specified in the Cloud Connector
            proxyUsername: connJwtToken,
            proxyPort: conSrvCred.onpremise_socks5_proxy_port,
            proxyHostname: conSrvCred.onpremise_proxy_host,
            //proxyScpAccount: 'myLocID',  // Cloud Connector's location ID if specified in the Cloud Connector
                                           // A location ID is used when multiple Cloud Connectors are connected to the same subaccount
            UID: 'USER1',
            PWD: 'Password1'
            //traceFile: 'stdout',
            //traceOptions: 'sql=warning'
        };
    
        var connection = hana.createConnection();
        connection.connect(connOptions, function(err) {
            if (err) {
                return console.error(err);
            }
            var sql = 'select * from HOTEL.CUSTOMER;';
            var rows = connection.exec(sql, function(err, rows) {
                if (err) {
                    return console.error(err);
                }
                console.log(rows);
                res.send(rows);
                connection.disconnect(function(err) {
                    if (err) {
                        return console.error(err);
                    }   
                });
            });
        });
    })
    
    const port = process.env.PORT || 3000;
    var server = app.listen(port, function () {
         var host = server.address().address
         var port = server.address().port
         console.log("Example app listening at http://%s:%s", host, port)
    })
    
    const _fetchJwtToken = async function(oauthUrl, oauthClient, oauthSecret) {
    	return new Promise ((resolve, reject) => {
    		const tokenUrl = oauthUrl + '/oauth/token?grant_type=client_credentials&response_type=token'  
            const config = {
    			headers: {
    			   Authorization: "Basic " + Buffer.from(oauthClient + ':' + oauthSecret).toString("base64")
    			}
            }
    		axios.get(tokenUrl, config)
            .then(response => {
    		   resolve(response.data.access_token)
            })
            .catch(error => {
    		   reject(error)
            })
    	})   
    }
    
    
  6. Redeploy the app.

    cd ..
    cf push
    
  7. The application running in the cloud, is now accessing data from an on-premise SAP HANA, express instance.

    Result

Congratulations, you have built, deployed and run an app that queries SAP HANA in Cloud Foundry and XS advanced as well as become familiar with the command line interface.

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