Jim Roepcke's weblog have browser, will travel (est. 1999)

links for 2009-09-29

• Joe Armstrong and Simon Peyton Jones discuss Erlang and Haskell
  (tags: erlang haskell programming fp concurrency distributed types tweet)

Calgary trip, Day 1

I'm in Calgary for the week. Arrived this afternoon. Got my luggage quick but that time advantage was erased by the doughebag taxi driver that took the scenic route to the B&B I'm staying at. I didn't notice until it was too late. Fuck.

Since I have to write a paper this week, and since I have a desk in my room, I decided to be clever and pack my 19" widescreen monitor and Apple aluminum keyboard. Took a minute to take the base off the monitor, packed flat in the suitcase, cake!

Got to the B&B to find out I'm staying in a different room this time. No problem... uh oh. No desk. LOL!

A quick call to the host fixed that though, I got moved to a room with a desk. Heh.

Walked to Vina's Pizza and Steak for dinner, that was really, really good. On the way back I stopped at the West Hillhurst Arena and watched the first few minutes of a Sr. Female hockey game. Apparently there's 4 tiers of (on average) 8 teams in that league. Gulp! I don't think we have 4 or 8 Sr. Female teams in Greater Victoria! And these ladies were seriously skilled. And I was told one of the players is the assistant coach of the Canadian National Ringette team. I'm pretty sure they could beat my team.

Now I'm back in my room watching the Oilers and the Canucks online and smack-talking the Canuck fans that are whining left, right and centre. It's 4-4 in the 3rd period.

On Tuesday I'll be trying something new - attending a lecture remotely over iChat! I left my Dell Mini 9 Hackintosh with a classmate, he'll be pointing the webcam at the prof and hopefully I'll be able to follow along and participate. I'm really excited about this, if it works I'll be so happy! We tested it and it worked so I'm pretty confident about it.

links for 2009-09-25

• Dictionary of Algorithms and Data Structures
  (tags: programming algorithms cs datastructures computerscience tweet)

links for 2009-09-17

• JSNES: A Javascript NES emulator
  (tags: javascript nintendo emulator tweet games canvas cool)
• BERT and Ernie: Scaling your Ruby site with Erlang
  (tags: erlang ruby github distributed rpc tweet bert ernie protocol)

NHL10, one thumb up, one down

I bought EA's NHL10 today. So far, I'm not liking it. The play is slower, and it seems like any time you skate near anyone from the opposing team, you lose the puck, even when they don't do anything to separate you from it.

There are some cool improvements though, like board play, so I'm hoping the game grows on me, but right now it's feeling like NHL09 may be the high water mark for the franchise, and a reminder that I should only buy the odd-year NHL games, as they seem to be better than the even-year games (with NHL94 being the obvious exception ).

PubSubHubbub plugin installed

I just installed the PubSubHubbub plugin into this site. Presumably, this means you can see updates live in Google Reader, Google Alerts, FriendFeed "and more".

If you don't know what PuSH is, check out the web site and this recent blog post for more information and background.

MonoTouch from Novell

Novell: MonoTouch

Congratulations to Novell for creating something almost relevant for the first time in years! I wonder what the runtime overhead is to load in the CLR... can't find mention of that on the site. iPhone apps run in a very memory-constrained environment, so whatever it is, it's not trivial.

I'm not a .NET/C# developer, so looking at the sample code was one of the first times I've ever looked at C# code. Is it really convention to capitalize method names? If so, why? Is this convention inherited from Visual Basic or something?

I'm sure this thing will improve, but right now there's no support for debugging, so good luck guys!

As with any bridged technology, if you want to get serious with it, you're going to have to know the underlying API and how to use it properly in its intended environment to be able to use it effectively in the bridged environment. So, what this means is quite a few Mono developers are going to be learning Objective-C soon. And hopefully they'll realize it's a heck of a lot easier than what they're using now.

MonoTouch looks like a great way to use .NET libraries (as long as they don't use the features that are disabled for MonoTouch) in an iPhone app, but I'm not sure I'd want to write an entire iPhone app in it.

Twitter’s Fail Whale on vacation

Twitter's in such bad shape right now they can't even muster up a fail whale. Isn't there a suitably-hyped new language they can rewrite their infrastructure in that will fix all this?

links for 2009-09-10

• Variables and the roles they play
  (tags: programming variables patterns roles)

Deactivated the WordPress RSS Cloud plugin

After some research into the architecture of RSS Cloud and how the WordPress plugin implements it, I decided to deactivate the WordPress RSS Cloud plugin.

In 2002 != 2009, a recent post on Scripting News, Dave Winer alluded to third-party concerns of scaling issues with RSS Cloud. A quick Google search uncovered the following scaling concerns:

Workbench: There's a Reason RSSCloud Failed to Catch On

techbrew: Is rssCloud All Wet?

BlogAnon: Why the RSS Cloud probably won't scale to Twitter like levels…

The blog posts exaggerate the problem, but if I understand things correctly, the problem is serious with regards to the WordPress plugin.

Every time you publish a new post to a WordPress site with N RSS Cloud subscribers, the RSS Cloud plugin sends N HTTP messages. Ideally, a site should only need to send one message, to a cloud server which manages the subscribers itself. Unfortunately, the WordPress plugin uses the WordPress site itself as the cloud server, so it bares the entire cost of providing real-time updates to your subscribers. With no cloud server involved, it's a purely client/server, unicast messaging situation with linear growth. That means very popular WordPress sites can easily DOS themselves every time a new post is published.

Each notification receiver (subscriber) fetches the updated feed. When you have a cloud server, it's possible to delegate caching the feed to a scalable location, but the WordPress plugin doesn't support that. So, each subscriber fetches your entire RSS feed, not just the new piece, from your WordPress site. That's a very signficant amount of instantaneous traffic hitting your server.

(If it isn't instantaneous, users wouldn't get real-time updates, which would make the whole system useless, thus, the traffic must arrive as soon as the subscribers can fetch it.)

I know my site isn't so popular it could suffer a DOS attack from RSS Cloud subscribers, even using the WordPress plugin as-is, but I also don't want to advocate the use of this plugin. Not just because it's a dangerous architecture, but because scalability and distributed systems are two of my research areas in my graduate studies, and frankly, I'd look foolish if I advocated using it.

It appears the RSS Cloud design can be quite scalable. One area of improvement would be to provide subscribers with deltas of the RSS instead of the entire feed, as pubsubhubbub does, but that's not an absolute dealbreaker. I'm not convinced the current RSS Cloud server implementation scales to huge numbers of subscribers or sites, but based on my limited research I think it's possible to do a very nice job on that part of the equation.

One concern for site publishers is analytics. Since the real-time feed requests do not have to go to the original server, real-time requests will not appear in their access logs. It would be up to the cloud server operator to provide access to that data (somehow, that is outside of the spec).

So why isn't wordpress.com getting DOS'd since all wordpress.com blogs now support RSS Cloud? The answer is simple, there aren't many RSS Cloud subscribers yet since very few people are using a compatible RSS feed reader today. It's a disaster waiting to happen, so the plugin will have to be improved and wordpress.com will need to implement a scalable RSS Cloud if it ever becomes popular on the reader-side.