Welcome To Erlang By Example

I’m Kevin Smith—the host of the Erlang by Example screencast series. I’d like to welcome you to the discussion forum for the series. Do you have questions about what you’ve seen in the screencasts? Or maybe a general Erlang programming question? Ask away and I’ll do my best to answer them.

When I try to open the .MOV files quicktime says “Error -2048: Couldn’t open the file **.mov because its not a file that QuickTime understands” Any ideas?

I’d like to see more advanced screencasts on topics like OTP, debugging/profiling Erlang code and so on.

@Mark – It sounds like the download didn’t complete so you might have a corrupt .mov file. Is it possible the file is getting truncated?

@Michael – I’ve got plans to move into OTP in the next couple of episodes. One of my goals for the series is to have the various components of the chat system running as gen_servers. The next episode is going to cover the basic of mnesia, which is an advanced topic on its own, I think.

Mark:

Perhaps up have to unzip them?

Regards

Dave Thomas

Yeah… They were Zip’s. Yet the download link was to a .mov. Everything is working now… Thanks!!!

Mark:

Thanks for bringing this to our attention. We’ve fixed the file names so that they consistently end in .zip.

What MACOSX Editor is is Kevin using in the training?

Is this good for those of use who have never used Erlang before? I’ve been programming for years and would like to use Erlang for some financial applications.

Great to see you guys doing this. I would note that it’s possible to get significantly better compression on screencasts if you use H.264 with low framerate (although I see you already have the framerate nice and low). In general you can get ~1 MB/min w/ H.264 tuned properly.

Just a random observation. :)

@Carl – I use Aquamacs Emacs as my editor of choice for all my Erlang coding needs. I’ve got a screencast up on my blog (http://weblog.hypotheticalabs.com) which illustrates how to setup an Emacs-based Erlang environment. The files to go along with the screencast are available for download, too.

@Shahbaz – I think so. The screencasts are targeted towards developers who have programming experience with other languages but who are new to Erlang. I don’t get into the details of the language, though. For that I’d recommend Joe Armstrong’s excellent “Programming Erlang”.

In route_messages receive block there is no recursion call after {recv_chat_msg,...

Ah, you detected and corrected this error in video 1 quite a bit later in the second video ;-) That’s how far I just got …

@Arie – Thanks for catching that! It looks like my refactoring went awry and I missed inserting that call. Of course, this suggests an episode on unit testing would be a Very Good Thing since proper unit tests would’ve caught this right away.

@Kevin: Very nice series – I look forward to seeing more of it.

@Michael: While I’m no Kevin Smith, I’ve put together what I think is a fairly easy to understand tutorial on simple OTP/gen_server usage. Here’s the link

@Dave: Thanks for the suggestion. We’ve tried H.264, but it tends to make the text look crunchy and washes out the colors. And since there’s a fair amount of coding in these screencasts, we ended up going with the Animation codec which makes the text clearer and more vibrant. It’s also pretty good at only recording the regions of the screen that have changed, making for relatively small file sizes.

I wish there was some kind of in-between “screencasting” codec, something like H.264 in the regions with lots of movement, but Animation crispness in the areas with little movement. If you have suggestions for tuning H.264, I’d love to learn how to use it better.

Thanks again!

Mike

Kevin,

Awesome series. I’m looking forward to seeing how the Erlang chat system can be used with Ruby clients. Can’t wait!

Peter

Hi Kevin. Really enjoyed the first episode, so much so that I wrote up a quick review. Looking forward to the rest of them…

Graham

Hi Kevin, I really liked the first four episodes. It got me some feeling for Erlang I could not get from reading tutorials. I would like to see OTP basics or an OTP overview.

Arne

Hi Kevin,

I’ve enjoyed your screencasts and have found them to be very helpful in understanding a number of items with regards to Erlang. What I’d find useful for future screencasts would be:

1) Unit tests
2) When to use / not use gen_server
3) How to handle large datasets with Mnesia
4) How to create network / application protocol servers or proxies

Regards,

Charles McKnight

Hi Kevin,

I thought it was standard to use a non-recursive init() instead of a flagged if/fail to do startups. I’m new, so I might be wrong.

I’m very interested in the basics of gen_server and the precepts of when it is appropriate to use it and when not to use it.

I’ve very much enjoyed every minute of every screencast. I appreciate learning about such libraries as mnesia, qcl, eunit, etc in a minimal-use context (which gives me the basics and allows me to understand the documentation for the first time). I would say the meta-information of “whys” and “by-the-ways” are the single most valuable aspect of language walkthroughs. I look forward to any and all future screencasts in the use of Erlang, even if it’s the same topics in a different use-case.

I would also be very interested in screencasts covering network / application protocol servers or proxies.