Facebook invites everyone to be involved

Facebook announced the Facebook Platform in May 2007 which I think is definitely one of the smartest moves Facebook has ever taken. There was only a few applications available in May 2007, but today, there are more than 350,000 active applications and 250 of which have more than one million monthly active users. The Facebook Platform provides an interface to developers to build applications within Facebook, it is just like an operating system provides an interface between hardware and programmers. One big difference is that Facebook's platform also provides a huge amount of very valuable social networking data.

Facebook's original goal is to let people connect to people. But connection itself is not going to be interesting enough to attract more people and connection needs people to grow. So Facebook needs applications to make itself interesting and useful. Instead of developing all kinds of applications by itself, Facebook give the opportunities to everyone. Facebook needs applications and applications need existing social network data. This is apparently a win-win game. Very smart!

Facebook Platform is very interesting to take a look at because it fits well into the software architecture of modern web-based applications. Before looking into how Facebook does it, ask yourself what you will do if you are asked to design such a platform. There are a few questions to answer:

• How to let developers access data in Facebook, with something that they are already familiar with, like SQL?
• How to let developers draw web content, with something that they are already familiar with, like HTML and CSS?
• How to let developers write dynamic web content, with something that they are already familiar with, like client-side JavaScripts?
• How to let developers do all above in a secured way?

I never developed Facebook applications, but after skipping through their documentation, the design is nice and straightforward to follow. When you develop a Facebook application, you use FQL to access data. FQL is very like SQL. It supports complex operation to reduce the number of requests you need to query. To draw web content, you have basically two choices, use FBML or an IFrame-based application. Jesse Farmer has a pretty nice introduction for FBML. But if you want to re-use some existing code, IFrame-based approach might work better for you. This article describes how to choose tween FBML and IFrame. Facebook Platform make dynamic and Ajax style content possible by providing FBJS. FBJS is a good balance between security and flexibility. One big problem of using FBJS is that many great JavaScript libraries won't work properly.

Facebook Platform is good, but its problem is that applications written with Facebook Platform need to run within Facebook. In many cases, applications that are outside of Facebook also want to utilize the social networking information in Facebook. Facebook announced Facebook Connect in Nov, 2008. It allows applications out of Facebook to access Facebook users' identity information, social graph and streams. A lot of good web applications start using Facebook Connect, such as Aardvark and many others. This is good for applications, because they can utilize the social networks that people already create in Facebook, instead of letting people create hundreds of different social networks. This is also critical for Facebook itself. Facebook oversees one way to gain revenue as to provide something like Paypal. This can becomes true only if Facebook Connect has a massive adoption.