Dealing with asynchronous http calls node js - node.js

Question

I have a RESTish api on a node js server. When it receives a GET request, it is to call a function that will then be calling another server get function. The code looks like this:
var server = http.createServer(function(request, response) {
console.log("YEAHHH! ", request.method);
var string='';
// Inside a request handler method
if (request.method == "OPTIONS") {
console.log("options");
// Add headers to response and send
//response.writeHead(statusCode, responseHeaders);
response.writeHead(success,responseHeaders);
response.end();
}
if(request.method == "GET") {
string = soso();
}
console.log("*******", string);
response.writeHead(success,responseHeaders);
response.end(string);
});
soso() is the call to the other server. The issue is I want to send the response of the soso() function before its finished so all I'm getting is an empty string.
How do I get around this?
I'm sure this is a duplicate but can't quite find what I'm looking for. So, any help is appreciated.
EDIT
Code for the soso function:
var soso = function () {
console.log("this is being called");
var options = {...}
var req = https.get( options, function(res) {
var str = '';
res.on('data', function ( chunk ) {
str += chunk;
})
res.on('end', function () {
console.log ( "str is: ", str );
string = str;
})
req.end();
console.log(res.statusCode);
console.log(responseHeaders);
});
}

Answer 1

You can try something like this , I am not sure. I have not tested this. Pass the response object in soso function, then use response.end(string); after get request gets end.
var server = http.createServer(function(request, response) {
console.log("YEAHHH! ", request.method);
var string='';
// Inside a request handler method
if (request.method == "OPTIONS") {
console.log("options");
// Add headers to response and send
//response.writeHead(statusCode, responseHeaders);
response.writeHead(success,responseHeaders);
response.end();
}
if(request.method == "GET") {
string = soso(response); //send response object as argument
} else {
console.log("*******", string);
response.writeHead(success,responseHeaders);
response.end(string);
}
});
soso function
var soso = fuction(response){ // we pass the response object in soso function
console.log("this is being called");
var options = {...}
var req = https.get( options, function(res) {
var str = '';
res.on('data', function ( chunk ) {
str += chunk;
})
res.on('end', function () {
console.log ( "str is: ", str );
string = str;
})
req.end();
response.writeHead(success,responseHeaders);
response.end(string);
console.log(res.statusCode);
console.log(responseHeaders);
});
}