The Whole Enchilada

Billing of web services is per hour of runtime, and the rates differ depending on the database instance class size [8] you use. The Angry Birds store uses different services worldwide: EC2 (Elastic Cloud 2) boots or shuts down virtualized servers. S3 stores data, such as images, which it keeps in long-term storage and distributes to the various servers. RDS manages databases; CloudFront delivers product images or skins as quickly as possible. Elastic Load Balancing (ELB) distributes the traffic and takes care of SSL termination, while the DNS service, Route 53, provides for cross-server or static IP addresses.

If you assign servers to groups (arrays), you get an overall picture of Rovio's AWS cloud architecture (Figure 4). The developers run two instances of the deploy infrastructure shown in the green area – one with the new version and the other with the previous version of the store. To roll back to an older version, they only need to switch Amazon's Route 53 DNS service [9].

Figure 4: The Angry Birds store is integrated with a complex structure of services that help it survive peak loads.

As a front-end array, only the Magento server (and associated databases) are otherwise used. For safety reasons, servers are redundant – if one fails, there is no need to boot another. The task of the front-end array is to process all dynamic requests (shopping carts, sessions, accounts) and guide visitors to checkout. The Varnish Array consists of two EC2 instances that run caching – the second server is also used as a fail-safe. The back-end array runs on a server and manages Rovio's products in Magento. Finally, a worker array handles all background processes.

Conclusions

AWS lets operators design stores that do not collapse when faced with peak loads  – that is, if you have the budget to build one. The store owner does not need to worry about revenue hits, and the admins have less work with the database. If sales are quiet, resources can be released manually or automatically. And, there is no need to do without the use of free software. At the same time, the combination of AWS and Magento with replicated databases creates a scalable and robust solution. After all, a collapsing building is for the birds.