Technical Articles

Jhodel Cailan

May 27, 2020 6 minute read

CAP: Consume External Service – Part 2

In my previous blog post Consume External Service – Part 1, I have tested the application using mock and real data. Just by configuring the NorthWind OData service URL in the credentials.url property, I was able to connect to the external service. This approach is only applicable for local development testing. If you try to deploy this into SCP Cloud Foundry, you will encounter an error stating that this approach is not valid for production use.

The reason behind this is that external service consumption in this CDS framework is meant to use the Destination Service in Cloud Foundry. And this is the topic of this blog — deploying the Node.js project into SCP Cloud Foundry using Destination Service.

Prerequisites

SAP Business Application Studio / Visual Studio Code
SAP Cloud Platform – Cloud Foundry Environment
You’ve already gone through Consume External Service – Part 1

Blog Post Series

Setup Destination Configuration

First of all, why do we need to setup a destination? A simple explanation is that it is best practice to avoid hard coding the external services that you use in your application inside your code. It is better for it to be configured separately from your application because as you deploy your application into different environment like DEV, QA, or PROD, you can have a different setup of the destination per environment. Also, it keeps the sensitive information like credentials outside of your code.

1. Create a Destination Service Instance in Cloud Foundry

Service Name: demo-destination
Plan: lite

2. Configure a new destination

You can also test the connection if the destination can be reached. A successful test will yield a message like the one below:

Connection to "NorthWind" established. Response returned: "307: Temporary Redirect"

That’s it! We have completed the setup of our destination.

Deploy the application to SCP Cloud Foundry

Now let’s go back to our Node.js project — if you were able to follow through my previous blog post, then your project will look exactly like the one I have below:

https://github.com/jcailan/azure-devops/tree/cap-es-part1

The next step is to prepare the application for deployment to SCP Cloud Foundry.

1. Generate the mta.yaml file using the command below:

> cds add mta

2. Generate security descriptor file xs-security.json using the command below:

> cds compile srv/ --to xsuaa > xs-security.json

For our case, we can ignore the warning shown in the terminal.

3. Update mta.yaml file with declaration of xsuaa and destination resources and then binding it to our node module demo-srv.

modules:
 # --------------------- SERVER MODULE ------------------------
 - name: demo-srv
 # ------------------------------------------------------------
   type: nodejs
   path: gen/srv
   properties:
     EXIT: 1  # required by deploy.js task to terminate 
   requires:
     - name: demo-destination
     - name: demo-uaa


resources:
 - name: demo-destination
   type: org.cloudfoundry.existing-service
   parameters:
     service-name: demo-destination

 - name: demo-uaa
   type: org.cloudfoundry.managed-service
   parameters:
     path: ./xs-security.json
     service: xsuaa
     service-plan: application

Note that in order for the destination service consumption to work, an xsuaa service is required to be bound to our application.

4. Update the package.json cds configurations to use the NorthWind destination we have configured in SCP Cloud Foundry:

	"cds": {
		"requires": {
			"NorthWind": {
				"kind": "odata",
				"model": "srv/external/NorthWind",
				"credentials": {
					"destination": "NorthWind"
				}
			}
		}
	}

5. Build the MTA Project by using the command:

> mbt build

Make sure you have saved all the files changes we did before doing the build.

An MTA archive file will be generated in the mta_archives folder.

6. Deploy the MTA archive file into SCP Cloud Foundry using the command:

> cf deploy mta_archives/demo_1.0.0.mtar

7. Once the deployment has completed, look out for the terminal logs which states the URL of your demo-srv module. In my case, here’s the generated URL:

s0017687913trial-dev-demo-srv.cfapps.eu10.hana.ondemand.com

Test the deployed Node.js app service

1. Open the URL we got from the previous step using your favourite browser, the initial page will show, and now click on the Products entity. You should see the result below:

As you can see, it is very easy to deploy the app and use the destination service. We don’t really need to do any additional JavaScript coding, all that we did is just do a little bit of configuration.

Testing the Node.js app locally

Now that we have deployed our application into SCP Cloud Foundry, we don’t really need to change the configuration back to a hardcoded external service URL just to test the app locally. We can test the app locally while still using the destination service in SCP Cloud Foundry. In order to be able to test locally, we need to capture the environment variable assigned to our Node.js module in SCP.

1. Get the VCAP_SERVICES environment variable settings for demo-srv module

Sample data structure to capture:

{
	"VCAP_SERVICES": {
		"xsuaa": [
			{
				"label": "xsuaa",
				"provider": null,
				"plan": "application",
				"name": "demo-uaa",
				"tags": [
					"xsuaa"
				],
				"instance_name": "demo-uaa",
				"binding_name": null,
				"credentials": {
					"tenantmode": "dedicated",
					"sburl": "https://internal-xsuaa.authentication.eu10.hana.ondemand.com",
					"clientid": "<<clientid>>",
					"xsappname": "demo!t48303",
					"clientsecret": "<<clientsecret>>",
					"url": "https://myaccount.authentication.eu10.hana.ondemand.com",
					"uaadomain": "authentication.eu10.hana.ondemand.com",
					"verificationkey": "<<key>>",
					"apiurl": "https://api.authentication.eu10.hana.ondemand.com",
					"identityzone": "myaccount",
					"identityzoneid": "3779d905-0123-45f2-a66d-e5c3a78cb1c4",
					"tenantid": "3779d905-0123-45f2-a66d-e5c3a78cb1c4"
				},
				"syslog_drain_url": null,
				"volume_mounts": []
			}
		],
		"destination": [
			{
				"label": "destination",
				"provider": null,
				"plan": "lite",
				"name": "demo-destination",
				"tags": [
					"destination",
					"conn",
					"connsvc"
				],
				"instance_name": "demo-destination",
				"binding_name": null,
				"credentials": {
					"uaadomain": "authentication.eu10.hana.ondemand.com",
					"tenantmode": "dedicated",
					"clientid": "<<clientid>>",
					"instanceid": "a82d0b2d-0119-4c09-97ee-46793ad8dba2",
					"verificationkey": "<<keyu>>",
					"xsappname": "clonea82d0b2d01194c0997ee46793ad8dba2!b48303|destination-xsappname!b404",
					"identityzone": "myaccount",
					"clientsecret": "<<clientsecret>>",
					"tenantid": "3779d905-0123-45f2-a66d-e5c3a78cb1c4",
					"uri": "https://destination-configuration.cfapps.eu10.hana.ondemand.com",
					"url": "https://myaccount.authentication.eu10.hana.ondemand.com"
				},
				"syslog_drain_url": null,
				"volume_mounts": []
			}
		]
	}
}

Note that the information contained in VCAP_SERVICES environment variable have credential information and shouldn’t committed in your git repository.

2. Create a file called default-env.json in the root of your project directory, and paste here the data you captured from SCP. If you are using the cds template project using the command cds init, then it has generated a .gitignore file that will automatically ignore default-env.json file we are creating here.
3. Next thing to do is start the app locally using the command:

> cds watch

4. Test the app on a browser by using the URL below:

http://localhost:4004/catalog/Products

As you can see we now can test the app locally using real data while also using the destination service of SCP Cloud Foundry.

If by any chance you still want to revert to testing the app using our mock data, you can still do so, you just need to amend the cds configuration in package.json to make the credentials section invalid. See below example:

	"cds": {
		"requires": {
			"NorthWind": {
				"kind": "odata",
				"model": "srv/external/NorthWind",
				"--credentials": {
					"destination": "NorthWind"
				}
			}
		}
	}

Save the changes and refresh your browser, then you will see the mock data is available again.

Closing

Now you know how easy it is to consume an external service using CAP Model and use Destination Service to manage the connection configuration. We also tested our application in three different ways:

Test the service directly in SCP Cloud Foundry
Test the service locally while still using SCP CF Destination Service
Test the service locally using mock data

Take note that mocking the data for your service is essential for automated unit testing, but this is another topic better dealt with over another blog.

UPDATE:

Taking this project further into — Unit Testing using Mocha and Chai

~~~~~~~~~~~~~~~~

Appreciate it if you have any comments, suggestions, or questions. Cheers!~

69 Comments

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Roc Antonio

June 3, 2020 at 10:24 am

Hi Jhodel, Im having troubles making the call to the destination it always prints a 500 erro with a 400 status code in the message. Also it says about not finding a proccess env called HTTPS_PROXY and then it fails the service run.

Don't know whats happening, and I followed your blog perfectly.

Thanks Jhodel Cailan

Jhodel Cailan

Blog Post Author

June 3, 2020 at 10:32 am

Hi Roc Antonio

It looks like the issue is in your configuration of default-env.json, make sure it has the right structure. Also, you need to make sure that the destination service and xsuaa services are setup properly.

Thanks and regards,

Jhodel

Luis Guillermo León Guzmán

June 9, 2020 at 5:27 pm

Hi Roc,

I has the same problem, have you found the way to resolve this?

Roc Antonio

July 9, 2020 at 12:34 pm

I was missing the Connectivity Service on the Cap Instance

Manu Gupta

July 20, 2020 at 5:01 pm

Hi Antonio,

I am also getting exact same error even after using full URL. How did you fixed that issue ?

I am getting this issue even for northwind odata.

Thanks,

Manu

Luis Guillermo León Guzmán

June 9, 2020 at 5:35 pm

Hi Jhodel,

Very useful post, I followed your steps and works fine, but now I want to replay this for a S/4HANA service, but I always get this error:

{"message":"Attempting to retrieve destination from environment variable.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.076Z","msg":"Attempting to retrieve destination from environment variable.","written_ts":1591723502076,"written_at":"2020-06-09T17:25:02.076Z"}
{"message":"Could not retrieve destination from environment variable.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.078Z","msg":"Could not retrieve destination from environment variable.","written_ts":1591723502078,"written_at":"2020-06-09T17:25:02.078Z"}
{"message":"Attempting to retrieve destination from service binding.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.078Z","msg":"Attempting to retrieve destination from service binding.","written_ts":1591723502078,"written_at":"2020-06-09T17:25:02.078Z"}
{"message":"Unable to find a service binding for given name \"SCP-TO-DEVVIRTUALNEO\"! Found the following bindings: s4cap-s4cap-uaa-S0019246072-workspKL8pDH6LAjq+PI9x, s4cap-conns4cap-S0019246072-workspOeKcqQC3TvHCyLFe, s4cap-s4cap-db-hdi-container-S0019dJBJdRo5DnLNI72P, s4cap-dests4cap-S0019246072-worksp6fvZ7pO3i0qk1mEo.\n ","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.079Z","msg":"Unable to find a service binding for given name \"SCP-TO-DEVVIRTUALNEO\"! Found the following bindings: s4cap-s4cap-uaa-S0019246072-workspKL8pDH6LAjq+PI9x, s4cap-conns4cap-S0019246072-workspOeKcqQC3TvHCyLFe, s4cap-s4cap-db-hdi-container-S0019dJBJdRo5DnLNI72P, s4cap-dests4cap-S0019246072-worksp6fvZ7pO3i0qk1mEo.\n ","written_ts":1591723502079,"written_at":"2020-06-09T17:25:02.079Z"}
{"message":"Could not retrieve destination from service binding.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.079Z","msg":"Could not retrieve destination from service binding.","written_ts":1591723502079,"written_at":"2020-06-09T17:25:02.079Z"}
{"message":"If you are not using SAP Extension Factory, this information probably does not concern you.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.079Z","msg":"If you are not using SAP Extension Factory, this information probably does not concern you.","written_ts":1591723502079,"written_at":"2020-06-09T17:25:02.079Z"}
{"message":"Attempting to retrieve destination from destination service.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.080Z","msg":"Attempting to retrieve destination from destination service.","written_ts":1591723502080,"written_at":"2020-06-09T17:25:02.080Z"}
{"message":"Unable to match a specific XSUAA service instance to the given JWT. The following XSUAA instances are bound: s4cap-SCPCFQAS91f91a19-69fd-4fcc-95de-a14f3e41a809!t4787. The following one will be selected: s4cap-SCPCFQAS91f91a19-69fd-4fcc-95de-a14f3e41a809!t4787. This might produce errors in other parts of the system!","level":"warn","custom_fields":{"package":"core","messageContext":"environment-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.081Z","msg":"Unable to match a specific XSUAA service instance to the given JWT. The following XSUAA instances are bound: s4cap-SCPCFQAS91f91a19-69fd-4fcc-95de-a14f3e41a809!t4787. The following one will be selected: s4cap-SCPCFQAS91f91a19-69fd-4fcc-95de-a14f3e41a809!t4787. This might produce errors in other parts of the system!","written_ts":1591723502081,"written_at":"2020-06-09T17:25:02.081Z"}
{"message":"Sucessfully retrieved destination from destination service.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.365Z","msg":"Sucessfully retrieved destination from destination service.","written_ts":1591723502365,"written_at":"2020-06-09T17:25:02.365Z"}
{"message":"OnPrem destination proxy settings from connectivity service will be used.","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.365Z","msg":"OnPrem destination proxy settings from connectivity service will be used.","written_ts":1591723502365,"written_at":"2020-06-09T17:25:02.365Z"}
{"message":"Unable to match a specific XSUAA service instance to the given JWT. The following XSUAA instances are bound: s4cap-SCPCFQAS91f91a19-69fd-4fcc-95de-a14f3e41a809!t4787. The following one will be selected: s4cap-SCPCFQAS91f91a19-69fd-4fcc-95de-a14f3e41a809!t4787. This might produce errors in other parts of the system!","level":"warn","custom_fields":{"package":"core","messageContext":"environment-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.366Z","msg":"Unable to match a specific XSUAA service instance to the given JWT. The following XSUAA instances are bound: s4cap-SCPCFQAS91f91a19-69fd-4fcc-95de-a14f3e41a809!t4787. The following one will be selected: s4cap-SCPCFQAS91f91a19-69fd-4fcc-95de-a14f3e41a809!t4787. This might produce errors in other parts of the system!","written_ts":1591723502366,"written_at":"2020-06-09T17:25:02.366Z"}
{"message":"Unable to create \"SAP-Connectivity-Authentication\" header: no JWT found on the current request.\n Continuing without header. Connecting to on-premise systems may not be possible.","level":"warn","custom_fields":{"package":"core","messageContext":"connectivity-service"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.538Z","msg":"Unable to create \"SAP-Connectivity-Authentication\" header: no JWT found on the current request.\n Continuing without header. Connecting to on-premise systems may not be possible.","written_ts":1591723502538,"written_at":"2020-06-09T17:25:02.538Z"}
{"message":"OnPrem destination proxy settings from connectivity service will be used.","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-09T17:25:02.539Z","msg":"OnPrem destination proxy settings from connectivity service will be used.","written_ts":1591723502539,"written_at":"2020-06-09T17:25:02.539Z"}
[2020-06-09T17:25:02.681Z | ERROR | 1003549]: Request failed with status code 403
[2020-06-09T17:25:02.681Z | ERROR | 1003549]: Error stacktrace: Error: Request failed with status code 403 at createError (/home/vcap/app/node_modules/axios/lib/core/createError.js:16:15) at settle (/home/vcap/app/node_modules/axios/lib/core/settle.js:17:12) at IncomingMessage.handleStreamEnd (/home/vcap/app/node_modules/axios/lib/adapters/http.js:236:11) at IncomingMessage.emit (events.js:323:22) at endReadableNT (_stream_readable.js:1204:12) at processTicksAndRejections (internal/process/task_queues.js:84:21)

This is my mta.yaml

ID: s4cap
_schema-version: '2.1'
parameters:
  deploy_mode: html5-repo
version: 0.0.1
modules:
  - name: s4cap-approuter
    type: approuter.nodejs
    path: s4cap-approuter
    parameters:
      disk-quota: 256M
      memory: 256M
    requires:
      - name: s4cap_html5_repo_runtime
      - name: dest_s4cap
      - name: conn_s4cap
      - name: s4cap-uaa
      - name: srv_api
        group: destinations
        properties:
          forwardAuthToken: true
          name: srv_api
          url: '~{url}'
  - name: s4cap_ui_deployer
    type: com.sap.html5.application-content
    path: s4cap_ui_deployer
    requires:
      - name: s4cap_html5_repo_host
    build-parameters:
      requires:
        - name: s4capui
          artifacts:
            - './*'
          target-path: resources/s4capui
  - name: s4cap-db
    type: hdb
    path: db
    parameters:
      memory: 256M
      disk-quota: 512M
    requires:
      - name: s4cap-db-hdi-container
  - name: s4cap-srv
    type: nodejs
    path: srv
    parameters:
      memory: 512M
      disk-quota: 512M
    provides:
      - name: srv_api
        properties:
          url: '${default-url}'
    requires:
      - name: s4cap-db-hdi-container
      - name: s4cap-uaa
      - name: dest_s4cap
      - name: conn_s4cap
  - name: s4capui
    type: html5
    path: s4capui
    build-parameters:
      builder: custom
      commands:
        - npm install
        - npm run build
      supported-platforms: []
      build-result: dist
resources:
  - name: s4cap_html5_repo_runtime
    parameters:
      service-plan: app-runtime
      service: html5-apps-repo
    type: org.cloudfoundry.managed-service
  - name: s4cap_html5_repo_host
    parameters:
      service-plan: app-host
      service: html5-apps-repo
    type: org.cloudfoundry.managed-service
  - name: s4cap-db-hdi-container
    type: com.sap.xs.hdi-container
    properties:
      hdi-container-name: '${service-name}'
  - name: s4cap-uaa
    type: org.cloudfoundry.managed-service
    parameters:
      service-plan: application
      service: xsuaa
      config:
        xsappname: 's4cap-${space}'
        tenant-mode: dedicated
      path: xs-security.json
  - name: dest_s4cap
    parameters:
      service-plan: lite
      service: destination
    type: org.cloudfoundry.managed-service
  - name: conn_s4cap
    parameters:
      service-plan: lite
      service: connectivity
    type: org.cloudfoundry.managed-service

and my package.json

{
	"name": "s4cap-srv",
	"description": "Generated from ../package.json, do not change!",
	"version": "1.0.0",
	"dependencies": {
		"@sap/cloud-sdk-core": "^1.17.2",
		"@sap/hana-client": "^2.4.196",
		"@sap/xsenv": "^2.2.0",
		"@sap/xssec": "^2.2.5",
		"@sap/cds": "^3.34.2",
		"passport": "^0.4.1",
		"express": "^4.17.1",
		"axios": "^0.19.2",
		"moment": "^2.24.0",
		"moment-timezone": "^0.5.28",
		"execution-time": "^1.4.1",
		"hdb": "^0.17.1",
		"uuid": "^3.4.0"

	},
	"engines": {
		"node": "^10 || ^12"
	},
	"devDependencies": {},
	"scripts": {
		"postinstall": "npm dedupe && node .build.js",
		"start": "node ./node_modules/@sap/cds/bin/cds.js serve gen/csn.json",
		"watch": "nodemon -w . -i node_modules/**,.git/** -e cds -x npm run build",
		"start:express": "node --inspect express.js"
	},
	"private": true,
	"cds": {
		"requires": {
			"db": {
				"kind": "hana",
				"model": "gen/csn.json"
			},
			"uaa": {
				"kind": "xsuaa"
			},
			"Z_OD_SCP_CORE_0001_SRV": {
				"kind": "odata",
				"model": "srv/external/Z_OD_SCP_CORE_0001_SRV",
				"credentials": {
					"destination": "SCP-TO-DEVVIRTUALNEO",
					"requestTimeout": 30000
				},
				"pool": {
					"min": 1,
					"max": 10
				}
			},
			"Z_OD_SCP_VEHI_SRV": {
				"kind": "odata",
				"model": "srv/external/Z_OD_SCP_VEHI_SRV",
				"credentials": {
					"destination": "SCP-TO-DEVVIRTUALNEO",
					"requestTimeout": 30000
				},
				"pool": {
					"min": 1,
					"max": 10
				}
			},
			"ZCDS_VW_TEST_CDS": {
				"kind": "odata",
				"model": "srv/external/ZCDS_VW_TEST_CDS",
				"credentials": {
					"destination": "SCP-TO-DEVVIRTUALNEO",
					"requestTimeout": 30000
				},
				"pool": {
					"min": 1,
					"max": 10
				}
			},
			"NorthWind": {
				"kind": "odata",
				"model": "srv/external/NorthWind",
				"credentials": {
					"destination": "NorthWind",
					"requestTimeout": 30000
				},
				"pool": {
					"min": 1,
					"max": 10
				}
			}
		},
		"auth": {
			"passport": {
				"strategy": "JWT"
			}
		},
		"odata": {
			"version": "v4"
		}
	}
}

The destination is been using without problems by other apps, but with this method using external services in CDS is not working.

Thanks in advance

Jhodel Cailan

Blog Post Author

June 10, 2020 at 11:03 am

Hi Luis Guillermo León Guzmán

I saw your post in the questions section, and it is true that you didn't configure the destination with the full URL of the external service. This is currently a limitation in the CDS framework.

Cheers!

Jhodel

Luis Guillermo León Guzmán

June 10, 2020 at 1:05 pm

Thank´s Jhodel,

Now it works with the full URL.

Best regards

Fadel Cazor

August 18, 2020 at 5:16 pm

Hi Luis,

If I use the URL instead of destination it works fine, but when I use destination it don't work anymore, need to use destination because using URL is not a suitable solution for my.

Can you share how to solve using destination please?

Thanks

{"message":"Attempting to retrieve destination from environment variable.","level
{"message":"Could not retrieve destination from environment variable.","level":"i
{"message":"Attempting to retrieve destination from service binding.","level":"in
{"message":"Unable to find a service binding for given name \"HorasHana\"! Found 
{"message":"Could not retrieve destination from service binding.","level":"info",
{"message":"If you are not using SAP Extension Factory, this information probably
{"message":"Attempting to retrieve destination from destination service.","level"
{"message":"Unable to match a specific XSUAA service instance to the given JWT. T
{"message":"Successfully retrieved destination from destination service.","level"
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found v
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found v
{"message":"Proxy settings for https are found in environment variables.","level"
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found v
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found v
{"message":"Proxy settings for https are found in environment variables.","level"
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found v
[2020-08-18T17:05:02.129Z | ERROR | 1885843]: Request failed with status code 404
[2020-08-18T17:05:02.129Z | ERROR | 1885843]: Error stacktrace: Error: Request fa

DJ Adams

June 10, 2020 at 10:43 am

This is a great pair of posts, nice work Jhodel!

Jhodel Cailan

Blog Post Author

June 10, 2020 at 11:07 am

Thanks DJ Adams ! It's an honor to be noticed by you! 😀

José Rubí Braña

June 15, 2020 at 4:00 pm

Hi again Jhodel,

I noticed that you cannot do expands with a remote service like this although you can do filters.

It's just me or its the same on all people ?

Thanks for the great post 😉

Jhodel Cailan

Blog Post Author

June 15, 2020 at 4:07 pm

Thanks Jose! Yes, it’s the framework issue ?. It is a limitation at the moment. If you really need this feature then you have to code it yourself — without the use of CDS fluent API.

Cheers! Jhodel

vasundhara lella

November 19, 2020 at 9:19 am

Hi Jhodel...

I am using on-premise s4h service. I want to read child entities by using $expand. without coding can we achieve it right now?

Chunyang Xu

June 23, 2020 at 9:08 am

Thanks Jhodel! Very clear step-by-step instructions, super helpful!

Jhodel Cailan

Blog Post Author

June 23, 2020 at 9:16 am

Happy to know that my post has helped you Chunyang!

Karthiheyan Murugesan

June 23, 2020 at 9:15 pm

Thanks, Excellent Blog, worked perfectly.

I want to expose few more entities . I did below changes and it is not working. What should I code more ?

using {NorthWind as external} from './external/NorthWind.csn';

service CatalogService {

@readonly

entity Products as projection on external.Products {

key ID, Name, Description, ReleaseDate, DiscontinuedDate, Rating, Price

};

@readonly

entity Productdetails as projection on external.ProductDetails;

}

-------------

const cds = require('@sap/cds');

module.exports = cds.service.impl(async function() {

const { Products,Productdetails } = this.entities;

const service = await cds.connect.to('NorthWind');

this.on('READ', Products, request => {

return service.tx(request).run(request.query);

});

this.on('READ', Productdetails, request => {

return service.tx(request).run(request.query);

});

Jhodel Cailan

Blog Post Author

June 24, 2020 at 12:11 am

Thanks Karthiheyan !!

Is it not working because you got an error? or because it doesn't show any data? I checked your code and it looks fine. You should just create a file called NorthWind-ProductDetails.csv which has a similar data like below:

ProductID;Details

1;Details of product 1

2;Details of product 2

Karthiheyan Murugesan

June 24, 2020 at 11:19 am

Hi,

It is working locally. But after deploy to CF , it is giving below error,

Request failed with status code 400 - error after clicking on Entityset in CF link.

| ERROR | 1806878]: Request failed with status code 400

Error stacktrace: Error: Request failed with status code 400 at createError (/home/vcap/app/node_modules/axios/lib/core/createError.js:16:15) at settle (/home/vcap/app/node_modules/axios/lib/core/settle.js:17:12) at IncomingMessage.handleStreamEnd (/home/vcap/app/node_modules/axios/lib/adapters/http.js:236:11) at IncomingMessage.emit (events.js:203:15) at endReadableNT (_stream_readable.js:1145:12) at process._tickCallback (internal/process/next_tick.js:63:19)

{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is undefined","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-06-24T11:11:03.415Z","msg":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is undefined","written_ts":1592997063415,"written_at":"2020-06-24T11:11:03.415Z"}

Karthiheyan Murugesan

June 25, 2020 at 11:35 am

Hi ,

It worked after specifying field names like ID,Name

@readonly

entity Suppliers as projection on external.Suppliers{

key ID,Name

};

Lalit Goyal

July 9, 2020 at 9:17 am

Hi Thanks Jhodel Cailan

Thanks for the well-written article.

I tried the steps. It worked fine in local but when deployed it gave me 500 (internal server error).

Can you please suggest how can I troubleshoot?

Regards,

Lalit

Jhodel Cailan

Blog Post Author

July 9, 2020 at 9:23 am

Hi Lalit Goyal

I assume that you were able to deploy it but when you are testing the service it gave you an error 500 Internal Server Error? If this is a yes, then go back to your terminal and execute below command

> cf logs <name of the cap service>

This will connect you to your deployed service and will see logs in real-time. Trigger again the service that is causing errors. Then analyze the logs from your terminal and see if you can find any clue.

Lalit Goyal

July 9, 2020 at 11:08 am

I am attaching the error here.

2020-07-09T16:34:50.49+0530 [APP/PROC/WEB/0] ERR [2020-07-09T11:04:50.497Z | ERROR | 1884455]: Failed to build
HTTP request for destination: failed to load destination!
2020-07-09T16:34:50.49+0530 [APP/PROC/WEB/0] ERR [2020-07-09T11:04:50.497Z | ERROR | 1884455]: Error stacktrace: Error: Failed to build HTTP request for destination: failed to load destination! at Object.errorWithCause (/home/vcap/app/node_modules/@sap-cloud-sdk/util/dist/error.js:6:20) at /home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/http-client/http-client.js:143:38 at process._tickCallback (internal/process/next_tick.js:68:7) Caused by: Error: Unable to get access token for "destination" service! No service instance of type "destination" found. at Object.resolveService (/home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/environment-accessor.js:190:19) at Object.<anonymous> (/home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/token-accessor.js:73:54) at step (/home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/token-accessor.js:45:23)
at Object.next (/home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/token-accessor.js:26:53) at /home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/token-accessor.js:20:71 at new Promise (<anonymous>)
at __awaiter (/home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/token-accessor.js:16:12) at Object.serviceToken (/home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/token-accessor.js:70:12) at /home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/destination-accessor.js:197:59 at step (/home/vcap/app/node_modules/@sap-cloud-sdk/core/dist/scp-cf/destination-accessor.js:45:23)

Lalit Goyal

July 9, 2020 at 4:54 pm

Also, I want to add that I am using a trial account.

Jhodel Cailan

Blog Post Author

July 11, 2020 at 3:19 am

Hi Lalit Goyal

I just got to know you have responded. Is your destination configuration correct? can you share your destination configuration?

Lalit Goyal

July 13, 2020 at 7:37 am

Hi Jhodel,

I am attaching the destination configuration screen shot.

Regards,

Lalit

Destination%20Configuration J

Destination Configuration

Jhodel Cailan

Blog Post Author

July 13, 2020 at 1:44 pm

Hi Lalit Goyal

It looks correct to me, except that the name of your destination is NorthWind_CLONING. If you named your destination like this, then you need to make sure you use this exact name on your configuration when you want to consume this destination from your CAP Model project.

Lalit Goyal

July 14, 2020 at 7:46 am

Hi Thanks Jhodel Cailan,

I found out the issue. Well, I didn't restart the application after binding to the destination.

After restarting the application, it worked. Maybe you can add that step too 😀

Thanks a lot for your help!

Regards,

Lalit

Jhodel Cailan

Blog Post Author

July 14, 2020 at 8:18 am

Hi Lalit Goyal

Glad to know that it is working fine now. There must be some steps that you did in between which requires a restart for your case. For my steps above, the destination was configured first, then build and deploy of MTA. The MTA will be the one who will bind to the service (auto-binding) and the app should be restarted afterward, hence, manual restart is not necessary.

Well, that's how we learn, which is by doing it! 🙂

Abe Dong

August 18, 2021 at 2:49 am

I was facing the same issue, but what I can see is that the service instance demo-destination and demo-uaa are not auto binding to the CAP app. after I created the binding manually, the service works as expected.

Christian Hanusch

July 16, 2020 at 1:58 pm

Hello,

I also have a problem getting this setup. Im using business application studio.

The error I get looks like this:

{"message":"Attempting to retrieve destination from environment variable.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:47.991Z","msg":"Attempting to retrieve destination from environment variable.","written_ts":1594907027991,"written_at":"2020-07-16T13:43:47.991Z"}
{"message":"Could not retrieve destination from environment variable.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:47.992Z","msg":"Could not retrieve destination from environment variable.","written_ts":1594907027992,"written_at":"2020-07-16T13:43:47.992Z"}
{"message":"Attempting to retrieve destination from service binding.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:47.992Z","msg":"Attempting to retrieve destination from service binding.","written_ts":1594907027992,"written_at":"2020-07-16T13:43:47.992Z"}
{"message":"Service of type destination is not supported! Consider providing your own transformation function when calling destinationForServiceBinding, like this:\n  destinationServiceForBinding(yourServiceName, { serviceBindingToDestination: yourTransformationFunction });","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:47.993Z","msg":"Service of type destination is not supported! Consider providing your own transformation function when calling destinationForServiceBinding, like this:\n  destinationServiceForBinding(yourServiceName, { serviceBindingToDestination: yourTransformationFunction });","written_ts":1594907027993,"written_at":"2020-07-16T13:43:47.993Z"}
{"message":"Could not retrieve destination from service binding.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:47.993Z","msg":"Could not retrieve destination from service binding.","written_ts":1594907027993,"written_at":"2020-07-16T13:43:47.993Z"}
{"message":"If you are not using SAP Extension Factory, this information probably does not concern you.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:47.993Z","msg":"If you are not using SAP Extension Factory, this information probably does not concern you.","written_ts":1594907027993,"written_at":"2020-07-16T13:43:47.993Z"}
{"message":"Attempting to retrieve destination from destination service.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:47.993Z","msg":"Attempting to retrieve destination from destination service.","written_ts":1594907027993,"written_at":"2020-07-16T13:43:47.993Z"}
{"message":"Unable to match a specific XSUAA service instance to the given JWT. The following XSUAA instances are bound: na-9e477645-d9fa-4701-94d2-055247d3f219!t19402. The following one will be selected: na-9e477645-d9fa-4701-94d2-055247d3f219!t19402. This might produce errors in other parts of the system!","level":"warn","custom_fields":{"package":"core","messageContext":"environment-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:47.994Z","msg":"Unable to match a specific XSUAA service instance to the given JWT. The following XSUAA instances are bound: na-9e477645-d9fa-4701-94d2-055247d3f219!t19402. The following one will be selected: na-9e477645-d9fa-4701-94d2-055247d3f219!t19402. This might produce errors in other parts of the system!","written_ts":1594907027994,"written_at":"2020-07-16T13:43:47.994Z"}
{"message":"Sucessfully retrieved destination from destination service.","level":"info","custom_fields":{"package":"core","messageContext":"destination-accessor"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:48.296Z","msg":"Sucessfully retrieved destination from destination service.","written_ts":1594907028296,"written_at":"2020-07-16T13:43:48.296Z"}
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:48.297Z","msg":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","written_ts":1594907028297,"written_at":"2020-07-16T13:43:48.297Z"}
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:48.297Z","msg":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","written_ts":1594907028297,"written_at":"2020-07-16T13:43:48.297Z"}
{"message":"Proxy settings for https are found in environment variables.","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:48.297Z","msg":"Proxy settings for https are found in environment variables.","written_ts":1594907028297,"written_at":"2020-07-16T13:43:48.297Z"}
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:48.297Z","msg":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","written_ts":1594907028297,"written_at":"2020-07-16T13:43:48.297Z"}
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:48.297Z","msg":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","written_ts":1594907028297,"written_at":"2020-07-16T13:43:48.297Z"}
{"message":"Proxy settings for https are found in environment variables.","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:48.297Z","msg":"Proxy settings for https are found in environment variables.","written_ts":1594907028297,"written_at":"2020-07-16T13:43:48.297Z"}
{"message":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-07-16T13:43:48.297Z","msg":"Try to fetch https_proxy or HTTPS_PROXY from the process env. Found value is http://127.0.0.1:8887","written_ts":1594907028297,"written_at":"2020-07-16T13:43:48.297Z"}

Thats my MTA.yaml:

_schema-version: '3.1'
ID: cmanagement
description: "Contract Management Application"
parameters:
  enable-parallel-deployments: true
version: 0.0.1


modules:

  - name: cmanagement-db
    type: hdb
    path: db
    parameters:
      memory: 256M
      disk-quota: 256M
    requires:
      - name: cmanagement-db-hdi-container

  - name: cmanagement-srv
    type: nodejs
    path: srv
    parameters:
      memory: 512M
      disk-quota: 256M
    requires:
      - name: cmanagement-db-hdi-container
      - name: my_destination_service_instance
      - name: cm_uaa


resources:
  - name: cmanagement-db-hdi-container
    type: com.sap.xs.hdi-container
    properties:
      hdi-container-name: ${service-name}

  - name: cm_uaa
    type: org.cloudfoundry.existing-service
    parameters:
       path: ./xs-security.json
       service-plan: application
       service: xsuaa

  - name: my_destination_service_instance 
    type: org.cloudfoundry.existing-service
    parameters:
       service-name: my_destination_service_instance 
       service-pan: lite
       service: destination

My Apps rootfolders package.json:

{
  "name": "cmanagement",
  "description": "Contract Management Application",
  "version": "1.4.0",
  "engines": {
    "node": "^12.16.1"
  },
  "dependencies": {
    "@sap/node-jwt": "latest",
    "@sap/cds": "^3.21.x",
    "@sap/cds-dk": "^1.8.5",
    "@sap/cds-odata-v2-adapter-proxy": "^1.4.30",
    "@sap/hana-client": "^2.4.167",
    "express": "^4.17.1",
    "hdb": "^0.17.1",
    "mbt": "^1.0.4",
    "sqlite3": "^4.1.1"
  },
  "devDependencies": {
    "axios": "^0.19.0",
    "eslint": "^6.7.2",
    "mocha": "^6.2.2",
    "nodemon": "^2.0.1"
  },
  "scripts": {
    "build": "cds build/all --clean",
    "start": "cds watch",
    "dev": "node --inspect=localhost:4014 node_modules/.bin/cds run --in-memory",
    "test": "mocha",
    "lint": "eslint .",
    "deploy:cds": "cds deploy",
    "build:mta": "cds build/all && cds deploy && mbt build -p=cf --mtar=cm.mtar",
    "deploy:cf": "npm run build:mta && cf deploy mta_archives/${npm_package_name}_${npm_package_version}.mtar"
  },
  "cds": {
    "requires": {
      "db": {
        "kind": "sqlite",
        "credentials": {
          "database": "cm.db"
        }
      },
      "API_BUSINESS_PARTNER": {
        "kind": "odata",
        "model": "srv/external/API_BUSINESS_PARTNER",
        "credentials": {
          "destination": "Q_BP",
          "requestTimeout": 30000
        }
      }
    },
    "auth": {
      "passport": {
        "strategy": "JWT"
      }
    }
  },
  "files": [
    "db",
    "srv"
  ]
}

And the default-env.json:

{
	"VCAP_SERVICES": {
		"destination": [
			{
				"label": "destination",
				"provider": null,
				"plan": "lite",
                "name": "Q_BP",
                "url": "https://placeholder-api.s4hana.ondemand.com/sap/opu/odata/sap/API_BUSINESS_PARTNER",
                "username": ...,
                "password": ...,
                
				"tags": [
					"destination",
					"conn",
					"connsvc"
				],
				"instance_name": "my_destination_service_instance",
				"binding_name": null,
				"credentials": {
					"uaadomain": "authentication.eu10.hana.ondemand.com",
					"tenantmode": "dedicated",
					"clientid": ...,
					"instanceid": ...,
					"verificationkey": ...,
					"xsappname": clone...,
					"identityzone": ...,
					"clientsecret": ...,
					"tenantid": ...,
					"uri": "https://destination-configuration.cfapps.eu10.hana.ondemand.com",
					"url": "https://placeholder-aws.authentication.eu10.hana.ondemand.com"
				},
				"syslog_drain_url": null,
				"volume_mounts": []
			}
		],
		"xsuaa": [
			{
				"label": "xsuaa",
				"provider": null,
				"plan": "application",
				"name": "cm_uaa",
				"tags": [
					"xsuaa"
				],
				"instance_name": "cm_uaa",
				"binding_name": null,
				"credentials": {
					"tenantmode": "shared",
					"sburl": "https://internal-xsuaa.authentication.eu10.hana.ondemand.com",
					"clientid": ...,
					"xsappname": ...,
					"clientsecret": ...,
					"url": "https://placeholder-aws.authentication.eu10.hana.ondemand.com",
					"uaadomain": "authentication.eu10.hana.ondemand.com",
					"verificationkey": ...,
					"apiurl": "https://api.authentication.eu10.hana.ondemand.com",
					"identityzone": "placeholder",
					"identityzoneid": ...,
					"tenantid": ...
				},
				"syslog_drain_url": null,
				"volume_mounts": []
			}
		],
		"hana": [
			{
				"label": "hana",
				"provider": null,
				"plan": "hdi-shared",
				"name": "cmanagement-db-hdi-container",
				"tags": [
					"hana",
					"database",
					"relational"
				],
				"instance_name": "cmanagement-db-hdi-container",
				"binding_name": null,
				"credentials": {
					"host": "z",
					"port": "",
					"driver": "com.sap.db.jdbc.Driver",
					"url": "...",
					"schema": "...",
					"hdi_user": "...",
					"hdi_password": "...",
					"user": "...",
					"password": "...",
					"certificate": "..."
				},
				"syslog_drain_url": null,
				"volume_mounts": []
			}
		]
	}
}

The destination configuration:

When accessing the entity I get this error:

<error xmlns="http://docs.oasis-open.org/odata/ns/metadata" ml-update="aware" ml-stage="preload" ml-view="top">
<code>500</code>
<message>Request failed with status code 404</message>
</error>

Jhodel Cailan

Blog Post Author

July 16, 2020 at 2:08 pm

Are you testing the service locally? For local testing you should use the "url" as credentials. The configuration you have in package.json is good for SCP deployment testing.

Christian Hanusch

July 16, 2020 at 2:24 pm

Hello Jhodel

Yes, I want to test locally using "cds watch". I tried doing that, the code looks like this:

      "API_BUSINESS_PARTNER": {
        "kind": "odata",
        "model": "srv/external/API_BUSINESS_PARTNER",
        "url": "https://placeholder-api.s4hana.ondemand.com/sap/opu/odata/sap/API_BUSINESS_PARTNER"    
      }

However now upon calling the entity I get this error:

<error xmlns="http://docs.oasis-open.org/odata/ns/metadata" ml-update="aware" ml-stage="preload" ml-view="top">
<code>501</code>
<message>The entity "API_BUSINESS_PARTNER.A_BusinessPartner" is annotated with "@sap.persistence.skip", please implement a custom handler for it.</message>
</error>

Jhodel Cailan

Blog Post Author

July 16, 2020 at 2:34 pm

Maybe the error was right? You don’t have a custom handler implemented? Did you read the first part of this blog post? In part 1, I have step there to implement the custom handler .js file.

Christian Hanusch

July 16, 2020 at 2:47 pm

I actually had, my cat-service-cds looks like this:

using { my.contractmanagement, sap.common } from '../db/data-model';
using { API_BUSINESS_PARTNER as ext } from './external/API_BUSINESS_PARTNER.csn';

service CatalogService {
    
    entity TreeItems as projection on contractmanagement.TreeItems;
    entity BusinessPartner @readonly as projection on ext.A_BusinessPartner;

}

The cat-service.js like this:

        const { BusinessPartner } = this.entities;
	    const service = await cds.connect.to('API_BUSINESS_PARTNER');
        this.on('READ', BusinessPartner, request => {
            return service.tx(request).run(request.query);
        });

What I did, I just changed:

this.on ('READ', BusinessPartner, async (req) => {
to

this.on('READ', BusinessPartner, request => {

Now this error pops up:

<error xmlns="http://docs.oasis-open.org/odata/ns/metadata" ml-update="aware" ml-stage="preload" ml-view="top">
<code>null</code>
<message>An error occurred during serialization of the entity collection. An error occurred during serialization of the entity at index #0 in the entity collection. Value of a structured property must be an object.</message>
</error>

Christian Hanusch

July 16, 2020 at 3:33 pm

If I console.log the query, I get a HTML structure returned, having this paragraph:

        <p><strong>Note:</strong> Since your browser does notsupport JavaScript, you must press the Continuebutton once to</p>

Jhodel Cailan

Blog Post Author

July 17, 2020 at 7:04 am

It's still tough to see where the issue is. If you can share the actual project you have right now through GitHub (or any other Git versioning tools), that would be great.

Manu Gupta

July 20, 2020 at 5:09 pm

Hi Christian Hanusch

I am also getting exact same issue after deploying the app to CF. Were you able to fix ?

I am getting this issue even for northwind odata.

Thanks,

Manu

Frank Lin

August 18, 2021 at 8:25 am

Hi Christian Hanusch

Any good news ? I got same issues .

Gaurav Karkara

July 16, 2020 at 5:43 pm

Hi Jhodel,

Thanks for such wonderful posts! I was able to follow and perform all the steps. Only part i am not able to make work was correct deploy to CF.

Though deploy is successful and when i open the link after deploy, i even see metadata. But when i click on 'Products', i get 500 internal server error. What could be the issue?

Gaurav

Jhodel Cailan

Blog Post Author

July 17, 2020 at 7:03 am

Thanks Gaurav Karkara !

500 internal server errors are usually brought by some problems with the implementation of the service. It's likely that you got some issues with your code, but I can't tell what is it based on the information provided.

What you can do is go to SCP Cockpit, navigate to the applications section and open the cap service details and extract logs there to view the logs information and try to make sense of what does the error logs tell you. Usually, it will become obvious where is the error from the logs, but if that's not the case, you can share it here so that we can analyze. Cheers!

Gaurav Karkara

July 17, 2020 at 7:28 am

Thanks Jhodel for replying.

I have looked at the logs and find the error:

'Unable to get access token for 'destination' service! No service instance of type 'destination' found.'

I have followed the exact steps as you have followed and my destination instance and corresponding entries in mta.yaml seems fine.

It doesn't look like it's because of code. It's something to do with destination instance access. Still trying to find..

Thanks for your support.

Gaurav

Gaurav Karkara

July 17, 2020 at 8:52 am

Worked. had to bind instances to applications. Thanks

Jhodel Cailan

Blog Post Author

July 17, 2020 at 8:55 am

Hi Gaurav Karkara

Good to know that you found the issue and it is now working! 😀

Karthiheyan Murugesan

July 20, 2020 at 9:35 am

Hi ,

Any lead on how to use service.tx(request).run(request.query) for a post call to S/4 odata.

Exact question

How to set header parameter for getting CSRF token in [ service.tx(request).run(request.query) ] . I want to set [X-CSRF-TOKEN : Fetch] in a GET request header so i can set back CSRF token in post call.

Regards,

Karthi

Jhodel Cailan

Blog Post Author

July 20, 2020 at 9:46 am

I'm afraid that you are going to code the logic for that on your own. According to the documentation below:

https://cap.cloud.sap/docs/guides/consuming-services#sending-requests

the fluent API can cater to do create (POST) request, however, from my experience, it didn't work when it starts to use the service via connectivity proxy. So what I did, is I have coded the solution my self using the axios node module -- it is the same node module that cap for node.js use.

Karthiheyan Murugesan

July 21, 2020 at 5:40 pm

Thanks Jhodel 🙂

Marco Moretti

August 5, 2020 at 7:09 pm

Hi guys,

is this working on webide or I should deploy to make it work? because I'm trying to access oData service but I receive

{"message":"Unable to create \"SAP-Connectivity-Authentication\" header: no JWT found on the current request.\n Continuing without header. Connecting to on-premise systems may not be possible.","level":"warn","custom_fields":{"package":"core","messageContext":"connectivity-service"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-08-05T18:49:38.260Z","msg":"Unable to create \"SAP-Connectivity-Authentication\" header: no JWT found on the current request.\n Continuing without header. Connecting to on-premise systems may not be possible.","written_ts":1596653378260,"written_at":"2020-08-05T18:49:38.260Z"}
{"message":"OnPrem destination proxy settings from connectivity service will be used.","level":"info","custom_fields":{"package":"core","messageContext":"proxy-util"},"logger":"sap-cloud-sdk-logger","timestamp":"2020-08-05T18:49:38.261Z","msg":"OnPrem destination proxy settings from connectivity service will be used.","written_ts":1596653378261,"written_at":"2020-08-05T18:49:38.261Z"}
Error: Failed to build HTTP request for destination: failed to build headers!

Jhodel Cailan

Blog Post Author

August 10, 2020 at 2:44 pm

The steps outlined in this blog post is not meant to be executed in SAP WebIDE. Read the prerequisites section for more information.

Fadel Cazor

August 18, 2020 at 10:48 pm

Hi Thanks Jhodel Cailan,

thanks a lot for this very well article, I’m tring with it since a few days ago. I'm trying to use an external Hana Odata service.

I achieved to make it work locally both with URL and destination, but in the latter case, for it to work I had to delete the node_modules directory, another case if this directory exists I can't reach the Odata and got an 404 or 500 error. I don’t understand why that happens, I suspect that there is some incompatibility between the npm packages that are in that directory and the components in the CF, or not?

Is there an option so that when deploying it does not take the npm packages that exist in the node_modules directory and instead uses the ones that exist in the CF?

Klaus Kopecz

August 19, 2020 at 10:00 am

I'm not sure why this should be the root cause of your issue, but you can avoid deploying the node_modules folder to CF in two ways:

if you use 'cf push', just delete the node_modules folder before pushing. The node.js buildpack on CF will then install all dependencies during staging.
if you use the MTA build tool 'mbt', then you can configure the module build within mta.yaml by using an 'ignore' directive for the node_modules folder. Just go to https://sap.github.io/cloud-mta-build-tool/configuration/ and check the section "Configuring module build artifacts to package into MTA archive".

Regards

Fadel Cazor

August 20, 2020 at 4:10 pm

Hi Klaus,

thanks for your answer, you are right the command "cf push" does not generate the directory "node_modules", instead it installs the dependencies in the process, however the process fails due to the following errors:

ERR npx: installed 4 in 1.686s
ERR command not found: cds
ERR npm ERR! code ELIFECYCLE
ERR npm ERR! errno 1
ERR npm ERR! aprhorasextras@0.0.1 start: `npx cds run`
ERR npm ERR! Exit status 1
ERR npm ERR! 
ERR npm ERR! Failed at the aprhorasextras@0.0.1 start script.
ERR npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
ERR npm ERR! A complete log of this run can be found in:
ERR npm ERR!     /home/vcap/app/.npm/_logs/2020-08-20T15_52_36_426Z-debug.log

My package.json file is:

    {
    "name": "aprhorasextras",
    "version": "0.0.1",
    "private": true,
    "devDependencies": {
        "@sap/cds": "^4.1.7",
        "@sap/eslint-plugin-ui5-jsdocs": "2.0.x",
        "@sap/ui5-builder-webide-extension": "1.0.x",
        "@sapui5/ts-types": "1.71.x",
        "@ui5/cli": "2.2.6",
        "bestzip": "2.1.4",
        "eslint": "5.16.x",
        "express": "^4",
        "rimraf": "3.0.2"
    },
    "ui5": {
        "dependencies": [
        "@sap/ui5-builder-webide-extension"
        ]
    },
    "scripts": {
        "start": "npx cds run"
    },
    "engines": {
        "node": "^8.0.0 || ^10.0.0",
        "npm": "^6.0.0"
    },
    "cds": {
        "requires": {
        "horasextras": {
            "kind": "odata",
            "model": "srv/external/horasextras",
            "credentials": {
            "destination": "HorasHana"
            }
        }
        }
    },
    "dependencies": {
        "@sap/cds-odata-v2-adapter-proxy": "^1.4.42",
        "@sap/xsenv": "^2.2.0",
        "@sap/xssec": "^2.2.5",
        "@types/jquery": "^3",
        "express": "^4",
        "passport": "^0.4.1"
    },
    "auth": {
        "passport": {
        "strategy": "JWT"
        }
    }
    }

Klaus Kopecz

August 20, 2020 at 7:03 pm

Hi Fadel,

I just have a vague idea what happened. Could you check in the log output of npm which npm registry is contacted to download the cds package? If it is still npm.sap.com, then this is a general issue, because cds 4 is not there. cds 4 is only available on npmjs.org. AFAIK, npm.sap.com will not be maintained anymore ...

Regards

Vikas Madaan

September 10, 2020 at 12:03 pm

When i am using destination with basic authentication then it is working fine. But when i am using destination of type OAuth2SAMLBearerAssertion then system is not able to retrieve destination.

cds.connect.to(‘SF’)

can above statement automatically pas required JWT token. Please help is very urgent.

I am also getting below error:

Unable to match a specific XSUAA service instance to the given JWT. Is this common?

@Jhodel

Can you please help here.

System is able to load destination with basic authentication but destination with type OAuth2SAMLBearerAssertion it is not.

Failed to build HTTP request for destination: failed to load destination!

---new update

Looks like cds.run and related statements don't support to pass JWT token to destination. Changing all the code to axios.

Sangita Purkayastha

March 17, 2021 at 1:19 pm

Hi Thanks Jhodel Cailan,

I followed the steps mentioned in your blog to consume an external service in my project using the destinations service instance.

I was successfully able to test the application locally, but as soon as I deploy the code to CF environment and try to access the service, I get 502 - Bad gateway error. Any idea what could be the reason for this error?

The cds > requires section in package.json file is as follows:

  "cds": {
    "requires": {
      "MyNumberRange": {
        "kind": "odata",
        "model": "srv/external/MyNumberRange",
        "credentials": {
          "destination": "number-range-dest"
        }
      },
      "db": {
        "kind": "sql",
        "[production]": {
          "kind": "hana"
        }
      }
    }
  },

Also the destination that was created is a shown below:

Regards,

Sangita Purkayastha

Jhodel Cailan

Blog Post Author

March 17, 2021 at 3:17 pm

Hi Sangita Purkayastha

The error 502 is very generic. Based on the information you provided, I can suspect that there can be an issue in your connection to HANA database. I suggest to do some troubleshooting on the deployed app like catching the error in the section of your code and logging the error into the console to get more information about the 502 error.

Zipei Chen

April 12, 2021 at 8:05 am

Hi Jhodel @Thanks Jhodel Cailan

Thank you very much for sharing the knowledge on this topic. I had similar issue here. Could you please kindly provide some hint on how to solve this issue?

When I tried to "Deploy the application to SCP Cloud Foundry", Using the created URL, i could access the top screen as shown below, but I can not enter the "Products" detail screen" only got 502 Bad Gateway error.

top top could be shown properly

Products%20page%20could%20not%20be%20shown

Products page could not be shown

Error message is shown as below.

<message>Bad Gateway</message>

</error>

I have checked the setting on CF side.

Destination service is defined as " api-access" and the "destination" is defined as "northwind" (tested as okay). And the service "demo-srv" is automatically binded to "api-access" and " demo-uaa" instance without error.

Anubhav Oberoy

April 26, 2021 at 3:59 pm

Guys,

Problem lies in your destination in CF, Check the name, It must be NorthWind where W must be caps. I would request to use the attached destination to import directly.

#
#Mon Apr 26 15:59:02 UTC 2021
URL=https\://services.odata.org/Experimental/OData/OData.svc
Name=NorthWind
ProxyType=Internet
Type=HTTP
Authentication=NoAuthentication
Description=NorthWind

THAJUNNIZA M A

May 26, 2021 at 10:14 am

I am also facing the same issue..Please help me how you resolved it

Carl Önnheim

April 11, 2021 at 10:36 pm

Hi Thanks Jhodel Cailan

Thanks for this article, very helpful and works like a charm!

Is it possible to reuse the external service in the local CAP model once defined? I.e. incorporate the external service built using this guide into another service which is running in the local data model.

In essence I have this external service (business partners from my backend ERP)

using businesspartner from './external/businesspartner.csn';

service businessPartnerService @(requires: 'authenticated-user') {
    @readonly entity BusinessPartner as projection on businesspartner.BusinessPartnerCollection;
}

Implemented like so:

const cds = require('@sap/cds');

module.exports = cds.service.impl(async function() {
	const { BusinessPartner, CurrentDefaultAddressInformation } = this.entities;
	const service = await cds.connect.to('businesspartner');
	this.on('READ', BusinessPartner, request => {
		return service.tx(request).run(request.query);
	});
});

Now I want to utilize that entity from another service, basically like this:

using { cuid } from '@sap/cds/common';
using businessPartnerService from './businesspartner-service';

service projectService @(requires: 'authenticated-user') {
    @readonly entity BusinessPartner as projection on businessPartnerService.BusinessPartner;
    entity ProjectDraft : cuid
    {
        title : String;
        customer : Association to businessPartnerService.BusinessPartner;
    }
}

This compiles fine and publishes the services. But if I try to navigate to a BusinessPartner entity from within the "projectService" I get:

Entity "projectService.BusinessPartner" is annotated with "@sap.persistence.skip" and cannot be served generically.

Can you shed some light on what the intended design pattern is here? I would like to avoid duplicating the code implementing the external service (and doing that causes other issues since the cds.connect.to('service') part only returns the actual service on the first shot).

Again, thanks for the guide and hoping for some input on this scenario.

Regards

//Carl

Tháyra Pedroso

September 11, 2021 at 11:39 pm

Hi Carl,

Did you solve this problem?

Carl Önnheim

September 20, 2021 at 7:49 pm

Hi,

No. I think it is doable but we also had issues with the external service being oData v2 and managing transposal between v2 and v4 became cumbersome. We decided to set up replication of the source objects into the CAP data model instead.

Regards

//Carl

Fedor Shestov

April 29, 2021 at 7:50 pm

Hi. When I'm deploying the file to BTP I get the error "In production mode it is required to set `options.destination`". How can I set it up? Thanks

Manikandan Kannan

May 26, 2021 at 1:42 pm

Hello Fedor,

I am getting the same issue. Did you fix this?

Fedor Shestov

May 27, 2021 at 3:06 pm

Hi. If you create an app from template then do not forget to add flag node start - productive

Simone Chiappin

June 8, 2021 at 12:21 pm

Hi Fedor,

Where did you insert this flag? I am getting the same issue

Fedor Shestov

June 8, 2021 at 12:34 pm

in mta

build-parameters:

before-all:

- builder: custom

commands:

- npm install --production

- npx cds-dbm build --production

Israel Garcia

July 5, 2021 at 10:13 am

hello,

I am getting the same issue. but i have the meta configuration with --production

build-parameters:

before-all:

- builder: custom

commands:

- npm install --production

- npx -p @sap/cds-dk cds build --production

any idea ?

Rajdeep BHUVA

July 29, 2021 at 5:05 am

Hi Jhodel Cailan,

Great Blog post!!

How can i consume non odata services into CAP ?

Thanks,

Rajdeep Bhuva

Technical Articles

CAP: Consume External Service – Part 2

Prerequisites

Blog Post Series

Setup Destination Configuration

Deploy the application to SCP Cloud Foundry

Test the deployed Node.js app service

Testing the Node.js app locally

Closing

Assigned Tags