I’ve just attended a Cloudstock session on Google App Engine and new Google platform technologies – an introductory talk by Google’s Christian Schalk.

App Engine has been a subject of considerable debate recently, thanks to a blog post by Carlos Ble called Goodbye App Engine:

Choosing GAE as the platform four our project is a mistake which cost I estimate in about 15000€. Considering it’s been my money, it is a "bit" painful.

Ble’s points is that App Engine has many limitations. Since Google tends not to highlight these in its marketing, Ble discovered them as he went, causing frustrations and costly workarounds. In addition, it has not proved reliable:

Once you overcome all the limitations with your complex code, you are supposed to gain scalabilty for millions of users. After all, you are hosted by Google. This is the last big lie.

Since the last update they did in september 2010, we starting facing random 500 error codes that some days got the site down 60% of the time.

Ble has now partially retracted his post.

I am rewriting this post is because Patrick Chanezon (from Google), has added a kind and respectful comment to this post. Given the huge amount of traffic this post has generated (never expected nor wanted) I don’t want to damage the GAE project which can be a great platform in the future.

He is still not exactly positive, and adds:

I also don’t want to try Azure. The more experience I gain, the less I trust platforms/frameworks which code I can’t see.

Ble’s post is honest, but many of the issues are avoidable and arguably his main error was not to research the platform more thoroughly before than diving in. He blames the platform for issues that in some cases are implementation mistakes.

Still, here at Cloudstock I was interested to see if Schalk was going to mention any of these limitations or respond to Ble’s widely-read post. The answer is no – I got the impression that anything you can do in Java or Python, you can do on App Engine, with unlimited scalability thrown in.

My view is that it pays vendors to explain the “why not” as well as the “why” of using their platform. Otherwise there is a risk of disillusionment, and disillusioned customers are hard to win back.