Earlier this year I was approached about writing a book on cloud computing topics by an editor for one of the big computer book publishers. Given that between my day job and having an infant I barely have time to keep this blog updated, I had to turn down the offer. However I did spend some time taking a second look at various cloud computing platforms like Amazon Web Services and Google App Engine then trying to put myself into the mindset of a potential customer as a way to figure out the target audience for the book. Below are the two categories of people I surmised would be interested in spending their hard earned cash on a book about cloud computing platforms

  1. Enterprise developers looking to cut costs of running their own IT infrastructure by porting existing apps or writing new apps. 
  2. Web developers looking to build new applications who are interested in leveraging a high performance infrastructure without having to build their own.

As I pondered this list it occurred to me that neither of these groups is well served by Google App Engine.

Given the current economy, an attractive thing to enterprises will be reducing the operating costs of their current internal applications as well as eliminating significant capital expenditure on new applications. The promise of cloud computing is that they can get both. The cloud computing vendor manages the cloud so you no longer need the ongoing expense of your own IT staff to maintain servers. You also don't need to make significant up-front payments to buy servers and software if you can pay as you go on someone else's cloud instead. Google App Engine fails the test as a way to port existing applications because it is a proprietary application platform that is incompatible with pre-existing application platforms. This same incompatibility rears its head when you look at App Engine simply as a way for enterprises to do new development. App Engine is based on Python, which if you look at the State of the Computer Book Market 2008, part 4 -- The Languages is not a terribly popular programming language. In today's world, enterprise development still means Java or .NET development which means enterprises will favor a platform where they can reuse their existing skills and technology expertise. Google App Engine isn't it.

So how about Web developers? In my classification, I broke up Web developers who'd be interested in cloud computing into hobbyists (like myself when writing a Twitter search engine on Windows Azure) and professionals (like myself when working on the platform that powers Hotmail's recently launched social features). Hobbyists either don't spend money or spend relatively little so I discounted them as a target audience of interest. The professional Web developers interested in cloud computing would be those who are considering Server or Web hosting but have concerns about scaling up if their service gets successful. After all, it seems like every week you are either reading about scaling hurdles that startup developers have faced as their applications become successful whether it is Bret Taylor's recent post How FriendFeed uses MySQL to store schema-less data or Jeff Atwood's Deadlocked! which talks about how he had to learn more about SQL Server's locking strategy as StackOverflow.com became more popular. The fact that Google App Engine is limited to only Python meaning that it is unavailable to developers using WISC platforms and only a subset of developers using LAMP can participate on the platform. Furthermore, there are key limitations in the platform that make it infeasible to build a full scale application. For example, Bret Taylor mentions that a consequence of having a denormalized database they need to run a background "Cleaner" process which fixes up data references and makes their database consistence. The App Engine DataStore API requires applications to store data in a denormalized way but there is no facility to run background processes to clean up the data as FriendFeed and most other large scale services which use database sharding often do. According to a recent blog post the Google App Engine roadmap has been updated so at least this limitation will be addressed. Other limitations for Python developers are that they can't use all of their existing knowledge of Python libraries since it only supports a subset of Python libraries. Database developers may be relieved that a lot of database management tasks no longer exist but may be chagrined once they see the restrictions on queries they can perform and hear some of the horror stories about query performance. At the end of the day, it just didn't seem to me that there were many professional Web developers who would put up with all of this pain over just going with AWS or dedicated hosting.

That said, Google App Engine does address the long tail of developers which I guess is nothing to sneeze at. Maybe it will see some success from targeting the low end in the same way that AdSense targeted the long tail of advertisers and is now the powerhouse of search advertising. Maybe. I doubt it though.

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