Consuming APC from UI5 Application running on BTP-CF

[ChrisTh]

Hello Experts,

I am struggling to create a websocket connection from my UI5 Application deployed on BTP (central launchpad) via CloudConnector to ABAP on-premise system (APC).

Here are some details:
SAP Cloud Connector Version: 2.14.0.1.(WebSocket checkbox is checked for the relevant host, resources are accessible)
ABAP System Version: SAP_BASIS 756
BTP-Subaccount-Destination could be accessed via BAS and works fine forall OData V2 requests

My UI5 application works as expected when I deploy it directly onto my ABAP system. As soon as I deploy it into my CloudFoundry space on BTP and try to connect to my apc channel the following error occurs:

WebSocket-dbg.js:409 WebSocket connection to 'wss://<my-prefix>.launchpad.cfapps.eu10.hana.ondemand.com/sap/bc/apc/sap/<my-apc-service>' failed:

OData requests to the same system work fine.

As we use the default managed app router of BTP-CF I added the following lines to my xs-app.json file:

  "websockets": {
    "enabled": true
  }

This is how I try to establish the connection:

jQuery.sap.require("sap.ui.core.ws.SapPcpWebSocket");
this.oWs = new sap.ui.core.ws.SapPcpWebSocket("/sap/bc/apc/sap/<my-apc-service>",sap.ui.core.ws.SapPcpWebSocket.SUPPORTED_PROTOCOLS.v10);

Are there any configuration steps I am missing? Do I for example need to create a separate destination for APC-web-socket-connections and add an additional route in xs-app.json?
Many thanks in advance,
Chris

[wridgeu]

Hi Christoph,

in fact my my problem was not solved but rather "postponed" as the particular user-case I'm having is not supported by BAS. You can find the influence/feature request I have created here: https://influence.sap.com/sap/ino/#/idea/291550/

Your use-case however reminds me of the following blog post: https://btp.udina.de/development/websocket.html#sap-btp-cloud-foundry-runtime and sounds like a supported use-case to me. Especially since you said that you fail to create a WebSocket connection after deployment not during development (which would be the BAS limitation). As far as I know the Application Router, Destination Service and SCC support the routing of WebSockets. Maybe the blog post itself can help you here (there is a section for the Destination service as well). I myself haven't deployed much on CF yet, especially not with WebSockets. I'm sorry that I can't help you more here.

Kind Regards,

Marco

[ChrisTh]

Hello Marco,

thank you for your comment. I'll try to get my use-case running with the help of the blog post you provided. (I already glanced at this blog before submitting my question yesterday but maybe I can find a solution in this blog if I read more thoroughly.)
I'll update this question in case I find a solution.

Best regards,
Chris

[ChrisTh]

Hello Experts,
just a little update. I took a deeper look into the URL of the websocket an changed it to match the URL of my OData-Service. The URL provided in my original questions has no relation to my app and therefore could not be matched to any of my destinations (as far as I understand the architecture). Now I am calling one of the two following URLs dependent on the way of calling the app (FLP or freestyle):

wss://<my-prefix>.launchpad.cfapps.eu10.hana.ondemand.com/<id-of-destination-service-instance>.<business-solution>.<application-name>/<build-timestamp>/sap/bc/apc/sap/<my-apc-service>

wss://<my-prefix>.launchpad.cfapps.eu10.hana.ondemand.com/<id-of-destination-service-instance>.<business-solution>.<application-name>-<application-version>/sap/bc/apc/sap/<my-apc-service>

I think the URLs look much better but still I can not establish a connection to the websocket and do not get a meaningful errormessage. I am still lost.

Any ideas for solving this issue are welcome.

[romulo_coutinho]

Any luck using it on the deployed version?

[ChrisTh]

Hello romulo_coutinho,
I was able to get it running properly. My problem was a wrong entry in cross-system-origin whitelist on my ABAP-Backend systems. As soon as I corrected this entry everything worked fine.

Best regards,
Chris

[gregorw]

Hi Christoph,

have you tried using the standalone approuter? Maybe the managed approuter despite the description from hschaefer123.

CU
Gregor

[ChrisTh]

Hello Gregor,
thank you for your reply.

My technical-support-department sent me several log files of our CloudConnector, WebDispatcher and ICM. I saw my requests on all those systems.
Inside those logs I saw that the origin header of the request did not contain port information. My cross-system-origin whitelist was maintained for port 443. I deleted the port from the whitelist and was able to establish the connection some minutes ago.

Best regards,
Chris