Live from AppDevCon in San Francisco

I’m here at AppDevCon in San Francisco, a gathering of Facebook developers, entrepreneurs, and investors hosted by SocialMedia‘s Seth Goldstein at the offices of Fenwick & West.

Today’s agenda:

12:30 – 1p: What is Engagement and why is it so important?
— Dave McClure (500 Hats)
— Seth Goldstein (SocialMedia)

1p: Creating, Spreading and Scaling Multi Million User Facebook Apps
— R. Tyler Ballance, (Slide)
— Blake Commagere (Vampires / Zombies)
— Dave Genztel, (SocialMedia)
— Jia Shen, (RockYou)
— Joe Winterhalter (Quizzes)
— James Hong (Hot or Not)

2p: Facebook Advertising Models
— Aryeh Goldsmith (Mybucks)
— Sourabh Niyogi (Appsaholic)
— Scott Rafer (Lookery)
— Narendra Rocherolle (fbExchange)
— Matt Sanchez (VideoEgg)
— Sundeep Ahuja (Appfuel)

3p: How to Value Facebook Apps?
— Eve Phillips, (Greylock)
— Keith Rabois, (Slide)
— Naval Ravikant, (Hitforge)
— Angela Strange, (AppFactory)
— Susan Wu, (CRV)

What is Engagement and why is it so important?

12:46pm: Dave McClure: Bake in a metrics system from day 1. Hypothesize the customer lifecycle and refine. Identify 5-10 conversion steps and put somebody on measuring it.

12:52pm: Dave McClure: Let’s not screw up this new ecosystem and fail to provide advertisers with effective metrics. We need some other usage metric than just users – like page views.

Creating, Spreading and Scaling Multi Million User Facebook Apps

1:04pm: Tyler Ballance (creator of Slide’s Top Friends, now with 12 million users): We’ve got a little social network inside your social network. Your top friends are the users you interact with the most. It’s really difficult to scale something after building it in your dorm room. Very difficult to keep persistent database connections open, very difficult to memcache very large amounts of data. Slide and RockYou have been able to do cool things because we’ve got caching servers. If you can afford an iframe, do it. If not, you’ve got FBML, but we all know that it breaks. They had the image caching collision issue where I had friends asking me why they showed up as furniture.

1:09pm: Jia Shen: We have to change things all the time. We’ve pretty much stayed away from all the caching stuff that Facebook offers. What we’ve done instead is build an infrastructure that allows us to regenerate all the profiles pretty quickly. They’re pushing FBML changes today and I’m just reading the post now.

1:19pm: Blake Commagere: Causes is an app with a lot of depth that I’m proud of. I also did Zombies, Vampires, and Werewolves, but they’re more like games. We think people want to compare themselves to others. That type of application is inherently more interesting. Collecting points for trivial activities within games – people love to get rewarded and compare. Let people show off what they’ve done. As you’re figuring out what you’re going to do with your apps, your database server is always going to be your constraint. We leverage memcache, we leverage Facebook’s caching. We chose Ruby on Rails because we could build our apps much faster with limited resources. Focus on your database and make sure it’s solid. We use MySQL on a machine with 32GB of RAM. Our app servers are cheap, but they do great. You don’t need 100 app servers to serve millions of users.

1:25pm: Joe Winterhalter: My inspiration came from what’s been successful on MySpace. Quizzes is about self expression. Create an incentive for you to have your friends involved. Most of our growth still comes from invites.

1:31pm: James Hong: We started out trying to create a bunch of different apps, now we’re focused on engagement. HotOrNot, HotLists, Pets, and Moods. Pets is driving millions of canvas page views a day. In our experience, database servers are not the bottleneck, Facebook’s proxying is. We’ve been using a lot of ajax. This does create issues if you want to refresh ads with ajax.