how can we make a call asynchronously through nodejs

[#1]

I have to build a mashup service in which i am making total of 6calls parallely.Through JS it wont be the best way to do it.

How can i achieve it through nodejs,I am new to this nodejs

Any example where anyone has done asynchronous calls through nodejs,Please share

Thanks

[phanim]

You can use Node JS community tools like "nimble" which help to perform multiple related tasks in sequence, in parallel and help to implement other useful and tricky scenarios.

http://caolan.github.io/nimble/

[#3]

Hi @shubham singh, welcome to Apigee Community!

The following is a snippet of a Node.js API Proxy making parallel calls using Promises.

app.get('/albums', function (req, res, next) {
  try {

    // get an array of promises of artists. Each artist to be passed as: e.g. artists[]=radiohead&artists[]=phoenix
    Promise.all(req.query.artists
        .map(function (artist_name) {
          return getAlbum(artist_name);
        }))
      .then(function (all_artists) {

        //convert each resolved promised into JSON and convert it into an array.
        res.json(all_artists.map(function (artist) {
          return JSON.parse(artist)
        }));
      })
  } catch (e) {
    res.send(e.message);
  }
});

// this is the function that makes the call to the backend. Note usage of request promise
function getAlbum(artist) {
  var options = {
    uri: 'http://lyrics.wikia.com/api.php',
    qs: {
      artist: artist,
      fmt: 'json',
      action: 'lyrics'
    }
  };
  return rp(options);
} 

Try this tutorial to learn step-by-step how to build this API Proxy and some foundations about JavaScript Promises.

https://github.com/dzuluaga/apigee-tutorials/tree/master/apiproxies/parallel-nodejs-api-proxy-with-p...

Hope it helps!

[asharma377]

thanks it is very descriptive and clean code. My requirement is little different though much on same lines. can you please share some thoughts

- In addition to "artist" that is passed as response, I want to insert "id" in response also when i aggregate and send the response along with other fields see the contract below. Basically some tweak before json.parse call.

{
	"12": {
		"Response": "Success",
		"StatusCode": 200,
		"artist": {
			"title": "Shipping Cost",
			"body": ""
		}
	},
	"13": {
		"Response": "Success",
		"StatusCode": 200,
		"artist": {
			"title": "Shipping Cost",
			"body": " "
		}
	},
	"14": {
		"Response": "Error",
		"StatusCode": 404,
		"ErrorMessage": "Content Not Found"
	}
}

- Also i want to count the array req param values and if they are greater than 10 then send a response error message and not process anything.

Please share your thoughts.

thanks,

Aakash