SAP BTP Cloud Foundry destination handler

Install

npm install --save sap-cf-destination

Prerequisites

• destination and destination instance created
• connectivity instance created
• xsuaa instance created
• all of the above instances bound to the node app, e.g. via manifest.yml:

  applications:
  - name: my_app
    path: my_app
    memory: 128M
    services:
      - xsuaa-instance
      - connectivity-instance
      - destination-instance

Usage

const callDestination = require('sap-cf-destination');

// Promise chain
callDestination({
        url: '/api/json',
        connectivity_instance: 'connectivity-lite',
        uaa_instance: 'uaa-lite',
        destination_instance: 'destination-lite',
        destination_name: 'tbaas',
        http_verb: 'POST',
        payload: {
            "me": "here"
        }
    })
        .then(response => {
            // do sth clever from the response
            // of $server_behind_destination_'tbaas'/api/json
        })
        .catch(err => {
            // oh no 💩
        })
        
// async/await? 👏
// add the 'async' keyword to an outer function wrapping 'callDestination'
async function getIt() {
    try {
        const response = await callDestination({...});
        // do sth clever w/ the response
    } catch (err) {
        // oh no 💩
    }
}

API

sap-cf-destination(options) ⇒ Promise.<(any|never)>

Param	Type	Description
options	Map	configuration options for several CF service instances
options.url	string	the url to call in the destination, absolute path (including leading slash) e.g. /api/v1/json
options.connectivity_instance	string	name of the instance of the connectivity service
options.uaa_instance	string	name of the instance of the uaa service
options.destination_instance	string	name of the instance of the destination service
options.destination_name	string	name of the destination to use
options.http_verb	'GET' | 'POST' | 'PUT' | 'PATCH' | 'DELETE' | 'HEAD' | 'OPTIONS'	HTTP method to use
[options.payload]	object	payload for POST, PUT or PATCH
[options.formData]	object	mimic a browser for POSTing a form to the destination; implies http verb POST
[options.content_type]	string	value for "Content-Type" http header, e.g. "application/json"
[options.full_response]	boolean	whether to have the full response (including all headers etc) pass through to the caller (BE -> proxy -> client)
[options.tech_error_only]	boolean	get a rejection only if the request failed for technical reasons, so e.g. 404 is considered a valid response
[options.binary]	boolean	whether to expect (and deliver) a binary at @param url
[options.scc_name]	string	Location ID of the SAP Cloud Connector

Hints & Limitations

• all major HTTP verbs are supported (GET, POST, PUT,PATCH,HEAD, DELETE,OPTIONS) per se
  BUT: if the proxy software decides to not let any of them pass through, the request originating from this module will of course fail
• POST, PUT and PATCH only support a JSON payload. The payload itself can be a plain, deeply nested object; it will be stringified automatically
• POST now supports both a JSON payload and a form-style ("like a browser") submission:

  callDestination({
    url: ...,
    http_verb: 'POST',
    formData: {
      field1: "some value",
      field2: JSON.stringify([ { "el1": "v1", "el2": "v2" } ])  // stringify deep nested objects and array structures
    }
  })

• use scc_name: '<locID>' as a parameter to specify location ID of the SAP Cloud Connector (default: none)

  callDestination({
          //...
          scc_name: '<locID of SCC>'
      }).then(...).catch(...);

• use full_response: true as a parameter to obtain the full response payload, e.g. to get access to response headers

  callDestination({
          //...
          full_response: true
      }).then(...).catch(...);

• use tech_error_only: true as a parameter to only get a rejection if the request failed for technial reasons ("as long as it has a status code, it's a valid response")

  callDestination({
          //...
          tech_error_only: true
      }).then( response => {
          // even ☕️ ends up here
          // add
          //    full_response: true (see above)
          // to get response.statusCode
      }).catch( err => {
          // network layer problem or such
      });

• do a download of a binary file by specifying the matching Content-Type of the file and setting binary to true;
  this will deliver a Buffer useable in writeStreams

  callDestination({
          //...
          content_type: 'application/zip',
          binary: true
      }).then( buffer => {
          // write Buffer
          fs.createWriteStream('file.zip')
            .write(buffer, 'binary')
            .end();
          // don't forget to listen to the error and finish event
          // ...
      }).catch(...);

License

Apache License 2.0

References

• code inspiration from https://github.com/bertdeterd/scc-connector
• ported Java reference code from https://help.sap.com/viewer/cca91383641e40ffbe03bdc78f00f681/Cloud/en-US/313b215066a8400db461b311e01bd99b.html