In this blog post, we will learn How to Connect to Cloud Services From CAP Application Locally

Though our SAP CAP Official Document is clearly explained hybrid-testing, I would like to illustrate with an use-case  “Connect to Northwind Cloud Service Locally in CAP Node JS Application using Function Import”

In General  Service can be from any external remote system or SAP System like S/4 HANA

For Example Business Partner OData service in SAP S/4HANA

Reference :  Connect to Remote Services from Local 

I assume you already aware how to integrate any Remote Service on BTP

• If it is Cloud Service for example (S/4 HANA Cloud ) then you need to use BTP Destination service
• If it is On Premise System which requires VPN to connect to then you need to use BTP BTP Connectivity service & SAP Cloud Connector

Reference : CAP BTP Connection – Destination

Target Audience

Developers

Prerequisites

I assume you already configured required services for CAP APP

Destination

Authorization and Trust Management Service XSUAA  Service

Sample Source Code

Below is sample CAP Node JS Source code to connect to BTP Destination

this.on(“getRemoteNWData”, async req => {

letresponse;

constcpqservice = awaitcds.connect.to(‘ext_northwind’)

try {

LOG.info(“start demo Northwind connecting”)

response = awaitcpqservice.send({

query:’GET /v2/northwind/northwind.svc/Products’,

headers: {

‘Content-Type’:’application/json’

}

})

LOG.info(“end Northwind connection “)

returnresponse;

} catch (error) {

req.error(500, error.message)

}

});

Scenario :  Use Local Application Destinations (Non BTP)

For Testing ,If you don’t want to use SAP BTP destinations, you can also define destinations, which means the URL, authentication type, and additional configuration properties, in your application configuration or code.

As of now only Basic Type authentication Destination works with Local CAP Destination

Refer : https://cap.cloud.sap/docs/guides/using-services?q=destination#app-defined-destinations

Scenario : On-Premise Connectivity

Few. SAP systems are located within a company’s internal network ,Example : S/4HANA On-Premise  , SAP ERP (CRM) … . They are not exposed to the internet. The SAP Cloud SDK provides helpful features to allow connecting to on-premise systems.

Reference : https://sap.github.io/cloud-sdk/docs/js/features/connectivity/on-premise

Consuming Services in CAP APP 

You can easily test your CAP application using a local database and mock ups. But at some point, you’re going to want to test with real cloud services. Of course, you can also deploy your application to the cloud & test but if you want to connect to Real Service locally before deploying to the cloud then you may want to run some ad-hoc tests,CAP Provides below options

Approach 1

• Create default-env.json
• Copy VCAP_SERVICES Values from BTP Environment Variable of your application
• run cds watch from terminal

Note :

https://cap.cloud.sap/docs/node.js/cds-env?q=default-env.json#in-default-envjson

Recently The use of default-env.json is deprecated

Approach 2 [Hybrid Testing]

A new approach to bind BTP services locally is to use cds bind

Execute below command with your service instance name ,service key as shown below from Terminal

cds bind -2 servicename:keyname

#1) cds bind -2 sap-organickart-destination-instance:sap-organickart-srv-key

#2)  cds bind -2 sap-organickart-auth:sap-organickart-auth-key

Alternatively you can also bind Multiple BTP Service Instances with One Command as shown below in shortcut by comma separated service instances

cds bind -2 servicename1,servicename2

Note : This implies that a service key exists with the suffix -key. In this example: sap-organickart-srv-key.

Example :

cds bind -2 sap-organickart-destination-instance,sap-organickart-auth

After cds bind  execution ,it will generate cdsrc-private.json file in project as shown below

Unlike Default-env.json which is un secure to maintain service sensitive data ,Running the “cds watch” in hybrid mode, which allows you to retrieve service credentials from BTP CF/Kyma on runtime

#3)  cds watch –profile hybrid

cds serve all –with-mocks –in-memory? –profile hybrid
watching: cds,csn,csv,ts,mjs,cjs,js,json,properties,edmx,xml,env,css,gif,html,jpg,png,svg…
live reload enabled for browsers
[bind] – resolving cloud service bindings…
[bind] – bound auth to Cloud Foundry service sap-organickart-auth key sap-organickart-auth-key
[bind] – bound destinations to Cloud Foundry service sap-organickart-destination-instance key sap-organickart-srv-key

Now you can browse your function import using local host port which fetch Products from NorthWind Remote  Services

Example : https://port4004-workspaces-ws-x.eu10.applicationstudio.cloud.sap/auth/getRemoteNWProducts()

Reference

Consuming Services

You can also use cds bind to set up testing to any BTP Service Instance

For Example :

• Connect Locally to SAP BTP Event Mesh instance 
• Bind a Local Application to Services on Kubernetes
• Binds a Local CAP Application  to a BTP  HANA instance