When a .NET Dev Decides It's Time for Node.js

Unless you’ve been living under a rock for the past couple of years, you’ll have heard the buzz about Node.js, a platform for building network applications in Javascript. If, like me, you’re a .NET developer working on Windows, you’ll have thought, ‘that’s nice, now back to work’. But I think it’s now time to consider adopting Node as a core part of our toolkit. It allows us to do some things far easier than we can with our existing tools, and it’s now mature enough on Windows that you don’t have to jump through hoops in order to use it. There’s a very nice IIS integration story now with iisnode.

Here’s a little example. I needed to write a little web service that simply waited for a second before responding. I wanted a harness to test the asynchronous IO handling in EasyNetQ. I’d written something to do this in .NET previously. Here’s my IHttpHandler implementation…

using System;
using System.Threading;
using System.Threading.Tasks;
using System.Web;

namespace TestHttpHandler
{
    public class TimerHandler : IHttpAsyncHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            throw new InvalidOperationException("This handler cannot be called synchronously");
        }

        public bool IsReusable
        {
            get { return false; }
        }

        public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback callback, object state)
        {
            var taskCompletionSouce = new TaskCompletionSource<bool>(state);
            var task = taskCompletionSouce.Task;

            var timer = new Timer(timerState =>
            {
                context.Response.Write("OK");
                callback(task);
                taskCompletionSouce.SetResult(true);
            });
            timer.Change(1000, Timeout.Infinite);

            return task;
        }

        public void EndProcessRequest(IAsyncResult result)
        {
            // nothing to do
        }
    }
}

It’s not trivial to write a non-blocking server like this. You have to have a good handle on the TPL and APM, something that’s beyond many mid-level .NET developers. In order to run this on a server I have to set up a new Web Application in IIS and configure the Web.config file. OK, it’s not a huge amount of work, but it’s still friction for a small throw-away experiment.

var http = require('http');

http.createServer(function (req, res) {
    setTimeout(function () {
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('OK');
    }, 1000);
}).listen(1338);

console.log('LongRunningServer is at http://localhost:1338/');

node LongRunningServer.js