callback to handle completion of pipe

I am using the following node.js code to download documents from some url and save it in the disk. I want to be informed about when the document is downloaded. i have not seen any callback with pipe.Or, Is there any 'end' event that can be captured on completion of download ?

request(some_url_doc).pipe(fs.createWriteStream('xyz.doc'));

Streams are EventEmitters so you can listen to certain events. As you said there is a finish event for request (previously end).

 var stream = request(...).pipe(...);
 stream.on('finish', function () { ... });

For more information about which events are available you can check the stream documentation page.

Based nodejs document, http://nodejs.org/api/stream.html#stream_event_finish, it should handle writableStream's finish event.

var writable = getWriteable();
var readable = getReadable();
readable.pipe(writable);
writable.on('finish', function(){ ... });

Code snippet for piping content from web via http(s) to filesystem. As @starbeamrainbowlabs noticed event finish does job

var tmpFile = "/tmp/somefilename.doc";

var ws = fs.createWriteStream(tmpFile);
ws.on('finish', function() {
  // pipe done here, do something with file
});

var client = url.slice(0, 5) === 'https' ? https : http;
client.get(url, function(response) {
  return response.pipe(ws);
});

I found an a bit different solution of my problem regarding this context. Thought worth sharing.

Most of the example create readStreams from file. But in my case readStream has to be created from JSON string coming from a message pool.

var jsonStream = through2.obj(function(chunk, encoding, callback) {
                    this.push(JSON.stringify(chunk, null, 4) + '\n');
                    callback();
                });
// message.value --> value/text to write in write.txt 
jsonStream.write(JSON.parse(message.value));
var writeStream = sftp.createWriteStream("/path/to/write/write.txt");

//"close" event didn't work for me!
writeStream.on( 'close', function () {
    console.log( "- done!" );
    sftp.end();
    }
);

//"finish" event didn't work for me either!
writeStream.on( 'close', function () {
    console.log( "- done!"
        sftp.end();
        }
);

// finally this worked for me!
jsonStream.on('data', function(data) {
    var toString = Object.prototype.toString.call(data);
    console.log('type of data:', toString);
    console.log( "- file transferred" );
});

jsonStream.pipe( writeStream );

Here's a solution that handles errors in requests and calls a callback after the file is written:

request(opts)
    .on('error', function(err){ return callback(err)})
    .pipe(fs.createWriteStream(filename))
    .on('finish', function (err) {
        return callback(err);
    });