Response not ending and browser keeps loading - nodejs and graphicsmagick - node.js

Question

I am new to nodejs. I am using graphicsmagick to resize the image before sending it to the browser.
My code looks like this (res is the response to be sent from function(req,res){...}) -
imageURLPromise
.then(function(response) {
var body = response.body;
if (body) {
console.log("Found From: " + response.request.uri.href);
//set response headers here
setResponseData(res, response);
var buf = new Buffer(body, "binary");
console.log(buf);
//gm module
gm(buf).resize(400,300).toBuffer(function(err,buffer) {
console.log("buffer here");
res.end(buffer, "binary");
});
}
}, function(error) {
console.log(error);
});
I get the image in the browser, I get the log "buffer here" but the browser stays in the "loading" state.
I have tried using .stream() with gm and pipe the stdout to response but it has the same problem.
If I do away with gm and directly write body to the response like this
res.end(body, 'binary');
then it works correctly.
Can someone tell what I am doing wrong here?

Answer 1

I figured out the problem.
The problem was not with node or gm but with the HTTP response headers.
When GM returns a buffer and we write that to the HTTP response then it sets the Transfer-Encoding header to "chunked". In that case the Content-Length header should never be set.
You can read more about it here
http://en.wikipedia.org/wiki/Chunked_transfer_encoding
Since I was setting both the browser kept waiting for content even after the image had been sent.
The code is exactly the same as I posted, except for the fact that in the setResponseData() function (which basically used to set headers) I am not setting the content-length header now.