Google App Engine is a unique hosting platform that lets you build applications and run them in Google’s data centers using the massive global infrastructure built to run the Internet’s most powerful company.

App Engine offers a development environment that uses familiar technologies (Java and Python) and provides a powerful and robust set of APIs to users while maintaining security and independence from other apps running in the cloud.
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Recently Google launched Google App Engine, a hosted dynamic runtime environment for Python web applications inside Google’s geo-distributed architecture.

Google App Engine is the latest in a series of Google-hosted application environments and the first publicly-available dynamic runtime and storage environment based on large-scale propriety computing systems.

Google App Engine lets any Python developer execute CGI-driven Web applications, store its results, and serve static content from a fault-tolerant geo-distributed computing grid built exclusively for modern Web applications. I met with the App Engine’s team leads on Monday morning for an in-depth overview of the product, its features, and its limitations.

Google has been working on the Google App Engine since at least March 2006 and has only just begun revealing some of its features.

In this post I will summarize Google App Engine from a developer’s point of view, outline its major features, and examine pitfalls for developers and startups interested in deploying web applications on Google’s servers.

• What is Google App Engine?
• Freemium hosting model
• The team
• Feature limitations
• Summary

What is Google App Engine?

Google App Engine is a proprietary virtualized computing suite covering the major common components of a modern web application: dynamic runtime, persistent storage, static file serving, user management, external web requests, e-mail communication, service monitoring, and log analysis.

The Google App Engine product offers a single hosted production web server stack hosted on Google’s custom-designed computers and datacenters distributed around the world.

Google App Engine is a managed hosting environment with a tightly managed stack running in a machine-independent environment. It simplifies the deployment and management of your web application software stack while constraining you to a specific stack. When I start a new web development project today I have to first setup a tiered system to effectively handle site growth:

1. Purchase dedicated servers or virtualized slices. Estimate necessary CPU, memory, disk space, etc. at each tier.
2. Configure a web server for dynamic content. Install Python and its eggs, Apache HTTPd and extra modules such as modwsgi. Configure and tweak each. Open appropriate ports. Listen.
3. Setup a MySQL database server and choose the appropriate storage engine. Configure MySQL, add users, add permissions. Tweak and optimize.
4. Add an in-memory caching layer for frequently accessed dynamic content.
5. Monitor your uptime and resource utilization with Ganglia and/or other tools on each machine.
6. Serve static files such as JavaScript, CSS, and images from a specialized serving environment such as Amazon’s Simple Storage Service.
7. Turn your static server into an origin server for a CDN with points of presence close to your website’s users.
8. Connect each piece of the stack, keep its software updated to avoid security vulnerabilities, and hopefully respond to all website requests in less than a second.
9. Dedicate work hours and expertise to all the above. Hire outside assistance if needed.
10. Don’t go broke trying.

Your tiers will expand as your new web application gains popularity. Your single-server tiers become load-balanced services, message bus broadcasts and listeners, and distributed cache arrays at scale. You’ll probably spend time rearchitecting your application at each stage of growth to incorporate for these new resource demands if you can afford the time, expertise, and effort.

Google App Engine is a new and interesting solution for Python developers interested in adding features, not servers.

Google spends hundreds of millions of dollars developing its custom infrastructure with 12-volt power supplies tapped into a hydro-electric dam next door and fat fiber pipes owned by local governments carrying requests and responses to their proper home. Google’s physical infrastructure is vast array of highly optimized web machines, and we’ll now be able to see how such infrastructure performs across more generic applications on App Engine.

Freemium hosting model

Google App Engine is a “freemium” business model offering basic features for free with paid upsells available for application developers exceeding approximately 5 million pageviews a month. This resource quota approximately matches the Google Analytics 5 million pageview limit. Google Analytics customers may currently exceed this limit if they maintain an active AdWords account with a daily advertising budget of $1 or more. The Google App Engine team plans to introduce pricing and service level agreements for additional resources, priced in a pay-as-you-go marginal resource structure, once the product leaves its limited 10,000-person preview period later this year.

Google publishes these quotas and provides administrative monitoring tools.

The quotas are just a guideline as Google may cut off access to your application if you receive a traffic spike of an unspecified duration.