Computing stuff tied to the physical world

Real-time out of the box

In Software on Dec 18, 2012 at 00:01

I recently came across SocketStream, which describes itself as “A fast, modular Node.js web framework dedicated to building single-page realtime apps”.

And indeed, it took virtually no effort to get this self-updating page in a web browser:

Screen Shot 2012-12-17 at 00.45.50

The input comes from the serial port, I just added this code:

Screen Shot 2012-12-17 at 15.48.50

That’s not JavaScript, but CoffeeScript – a dialect with a concise functional notation (and significant white-space indentation), which gets turned into JavaScript on the fly.

The above does a lot more than collect serial data: the “try” block converts the text to a binary buffer in the form of a JavaScript DataView, ready for decoding and then publishes each packet on its corresponding channel. Just to try out some ideas…

I’m also using Jade here, a notation which gets transformed into HTML – on the fly:

Screen Shot 2012-12-17 at 15.53.56

And this is Stylus, a shorthand notation which generates CSS (yep, again on the fly):

Screen Shot 2012-12-17 at 15.54.25

All of these are completely gone once development is over: with one command, you generate a complete app which contains only pure JavaScript, HTML, and CSS files.

I’m slowly falling in love with all these notations – yeah, I know, very unprofessional!

Apart from installing SocketStream using “npm install -g SocketStream”, adding the SerialPort module to the dependencies, and scratching my head for a few hours to figure out how all this machinery works, that is virtually all I had to do.

Development is blindingly fast when it comes to client side editing: just save any file and the browser(s) will automatically reload. With a text editor that saves changes on focus loss, the process becomes instant: edit and switch to the browser. Boom – updated!

Server-side changes require nodemon (as described in the faq). After that, server reload becomes equally automatic during development. Pretty amazing stuff.

The trade-off here is learning to understand these libraries and tools and playing by their rules, versus having to write a lot more yourself. But from what I’ve seen so far, SocketStream with Express, CoffeeScript, Jade, Stylus, SocketIO, Node.js, SerialPort, Redis, etc. take a staggering amount of work off my shoulders – all 100% open source.

There’s a pubsub-over-WebSockets mechanism inside SocketStream. Using Redis.

Wow. Creating responsive real-time apps hasn’t been this much fun in a long time!

  1. You might also want to check out Meteor ( It can make real-time stuff a joy.

    • Thanks – yes, I did look into Meteor a bit. I found SocketStream somewhat easier to get started, and giving me more options to try out different package combinations. Both get client and server tied together in a very nice way – see also this informative weblog post by Steven Sanderson about several options (including Meteor but not SocketStream).

  2. Still reading daily, and I like where this is going! (Another pointer …

  3. Any suggested reading list? — I suppose one needs a basic understanding of Javascript before looking at Node? I may have some time for reading during Christmas or New Years. thanks!

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