Cross-domain Data

Web applications using AJAX to obtain third party data must deal with the browser's same-origin policy. Typical workarounds include either JSONP or the use of a service proxy on the home domain. Both techniques bring trade-offs. JSONP removes the same-origin barrier but leaves the cross-domain security hole in place; a third party service can execute arbitrary JavaScript on the client site. Service proxies offer more safety at the cost of new infrastructure and code that must be maintained.

A Rails app serving API data can now provide a third option without opening security holes or requiring new infrastructure for client sites.

AJACSS Sounds Like AJAX

Asynchronous JavaScript and CSS, also known as CSSHttpRequest, is a method of URI-encoding data in 2KB chunks split over several CSS rules with a modified data URI scheme. Because CSS is not subject to the same-origin policy, no service proxy is required. Moreover, because this is CSS, the security concerns of JSONP no longer apply. Here's an example CSS snippet with an encoded "Hello Rails" message:

 #c0 { background: url(data:,Hello%20Rails); }

Shopping for Rack Middleware

If you're in need of a piece of Rack middleware, there are two places to check before rolling your own -- the Rack wiki and rack-contrib on GitHub. In the case of CSSHttpRequest, we can just grab a pre-made piece of middleware and drop it into our Rails app thanks to Cameron Walters from nb.io.

In config/environment.rb, add the following code inside the Rails::Initializer block:

# First specify the required gems so that rake gems:install will install them
config.gem "rack-contrib", :lib => 'rack/contrib/csshttprequest'
config.gem "nbio-csshttprequest", :lib => "csshttprequest", :source => "http://gems.github.com/"

# Next, load Rack::CSSHTTPRequest in your middleware stack
config.middleware.use 'Rack::CSSHTTPRequest'

That's it! Rack::CSSHTTPRequest will automatically encode the output for any request using the "_format=chr" convention used by Rails. Other web apps and services can use the data without exposing security holes or requiring new infrastructure.

h2. Keynote Flex Preview

During our keynote presentation, Agility in Deployment, we previewed several exciting Flex features queued for release in late June of this year. Flex is a cloud computing platform built on Amazon EC2 for hosting real world Rails applications, running everything from Passenger to Rack, Merb, Sinatra, and more.

h2. Instant Self-Healing Clusters

If you're familiar with our existing Solo platform, Flex takes it to the next level, introducing one-click provisioning of dedicated, load-balanced, self-healing clusters. Adding or removing servers is as simple as clicking a button. If at any time a node in your cluster should become unresponsive, it will be decommissioned and a replacement will take over automatically.

While building Flex, we added some powerful tools to our cloud platform that we couldn't resist adding to Solo. Even better, they are all available today for all Solo users.

h2. Deploy from the Web, Deploy from Git

Nearly all of our customers use Capistrano for deployment and for good reason; it encapsulates several best practices in an automated fashion that take the guesswork out of deploying Rails applications. We have taken these conventions and wrapped them in a single "Deploy" button, available on every customer's Cloud Dashboard.

For those of you who prefer the command line, this new method of deployment is also available via Git. Just push to your repository using a tag that specifies your environment and any migrations that need to be run, and that's it. The Engine Yard Cloud takes care of the rest. Both web deployment and Git push support work alongside Capistrano, allowing you to choose the tool that best fits your team's workflow.

h2. Real Production Clones

Hosting real applications with real users means taking each deployment seriously. As Ruby developers, we test everything because we believe in the value it provides. This same mindset should be applied to deployment.

Using the Engine Yard cloud makes this a snap. With one click, you can clone any production environment to practice deployment and rollback prior to affecting your customer data. So called "staging" environments are often under-powered and lag behind production environments when upgrades take place. Cloud computing with Engine Yard allows you to make an exact copy of your production environment for just as long as you need it. When you're confident in your deployment, you can shut down the staging environment with a click of a button, paying only for the minutes used.

h2. Your Business in the Cloud

There is a fundamental shift underway for deployment. Forward thinking businesses can use this to their competitive advantage to increase quality and uptime as well as decreasing time to market. At Engine Yard, we want to enable our customers to take advantage of this shift and we welcome you to join us in the Cloud.

For more information, be sure to check out the Flex Press Release.