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Showing posts from November, 2010

Software Engineering: Coping When You Must Repeat Yourself

These days, most software engineers are familiar with the acronym "DRY" which stands for "don't repeat yourself". In general, it's good advice. In a perfect world, no code would ever be duplicated and every piece of "truth" would only exist in one place. However, the real world isn't quite so perfect, and things are far less DRY than you might imagine. The question is, how do you cope?

First let me show you some reasons why you can't always keep it DRY:

Often, the same truth is duplicated in the code, the tests, and the docs. Duplicating the same piece of truth in the code and in the tests helps each verify the other. Generally, the code is more general than the tests (the tests verify examples of running the more general code), but the duplication is there. When you update one (for instance to change the API), you'll need to update the other. This is a case where not keeping it DRY pays off--if you have to update the tests, that…

JavaScript: Naughty Socket.IO Example

File this under the "things you probably shouldn't do, but are fun anyways" category. Socket.IO is a library for Node.JS that provides Comet using a plethora of different approaches (WebSocket, Flash socket, AJAX long polling, etc.). I hacked the Socket.IO chat demo so that it reads HTML from my terminal and just dumps it to the browser. Hence, I can control people's browsers from my terminal. Insecure? Yeah. Fun? Oh yeah!

Anyway, here's how I hacked the server.js file in Socket.IO's chat demo:io.on('connection', function (client) {

// Read from /dev/tty and send it to the browser.
var stream = fs.createReadStream('/dev/tty', {encoding: 'ascii'});

stream.on('error', function (exception) {
client.send({announcement: 'Exception: ' + exception});

stream.on('data', function (data) {
client.send({html: data});
...And here's how I hacked chat.html:function message(obj) {
var el = document.createE…

Jobs: Looking for People to Work With Me

I'm really enjoying myself here at Twilio. We're looking for a few more people, and I wonder if any of my readers would like to come work with me.

Twilio makes it easy for normal web developers to write voice and SMS enabled applications. If you don't know what I mean, try calling my app: (888) 877-7418. By the way, Jeff Lindsay, the SHDH house guy, is here too.

Here are the positions we're hiring for:DevOps EngineerSenior Software EngineerCore TeamSoftware Engineering Leader, Organizer, MentorCustomer AdvocateDeveloper EvangelistProduct ManagerWe use a mix of Python, Java, PHP, and Ruby. We're in San Francisco. We just closed a second round of funding, but we also make a lot of money.

Here are the actual job postings. Contact Joanna Samuels for more information.

Books: Digital At Work: Snapshots From The First Thirty-Five Years

I just finished reading Digital At Work: Snapshots From The First Thirty-Five Years."Digital At Work" tells the story of the first thirty-five years of Digital Equipment Corporation [DEC] and illuminates the origins of its unique culture. First person accounts from past and present members of the Digital community, industry associates, board members, and friends - plus a wealth of photos from Digital's archives - trace the company's evolution from the 1950s to present.In short, I really enjoyed it. By reading this book, I was able to vicariously experience the growth and history of one of the most significant companies in the history of computing, and it definitely left an emotional impact.

I think one of the most interesting things about Digital was its culture. Some people might call it chaos. Other people might call it a meritocracy. It was definitely in the MIT tradition. It wasn't uncommon to get into shouting matches over which approach to take. Good i…

Linux: The Tiling Window Manager I Wish I Had

Every year or two, I switch to a tiling window manager such as xmonad or dwm. Inevitably, I switch back to GNOME after a couple weeks. Sometimes it's because the window manager doesn't fit in with the rest of my GNOME desktop (it used to be non-trivial to get xmonad to work with GNOME's panel). Sometimes it's because of bugs related to having a weird window manager (NetBeans used to freak out with xmonad, and Flash refused to go full-screen). Every time I try again, a bunch of things have improved. xmonad even had a project aimed at making it more accessible to GNOME users. Still, I think the biggest problem I have is that tiling window managers make some assumptions that just don't work out for me in practice.

I use more than just terminals. I still like to use things like GVim, the GIMP, Google Chrome, a graphical chat client, etc. In fact, I even get a real kick out of writing GUIs. Some tiling window managers assume you're going to live in a termina…

JavaScript: A Second Impression of NodeJS

When I first heard about NodeJS, my reaction was, "Why would I use JavaScript on the server when there are similar continuation-passing-style, asynchronous network servers such as Twisted and Tornado in Python already? Python is a nicer language. Furthermore, I prefer coroutine-based solutions such as gevent and Concurrence." However, after watching this video, Ryan Dahl, the author of NodeJS, has convinced me that NodeJS is worthy of attention.

First of all, NodeJS is crazy fast. Dahl showed one benchmark that had it beating out Nginx. (However, as he admitted, it was an unfair comparison since he was comparing NodeJS serving something out of memory with Nginx serving something from disk.) It's faster than Twisted and Jetty. That last one surprised me.

Dahl argued against green thread systems and coroutine-based systems due to the infrastructural overhead and magic involved. He argued that he doesn't like Eventlet because it's too magical both at an implem…