Cloud Application Architectures

Types of Clouds

Infrastructure clouds (aka “Infrastructure-as-a-Service,” or IaaS) can be built primarily in two ways: service infrastructures or cloudcenters. Both allow all of the capabilities one expects from IaaS:

• Scale on demand

• Pay-as-you-go

• Conversion of capital expenditures (CapEx) to operational expenditures (OpEx)

• Programmatic (API) and graphical user interfaces (GUI)

• Basic infrastructure: storage, servers, network, power, and cooling

Although both provide the same basic value, these two approaches differ significantly in approach:

Service infrastructures

This is the approach made familiar by AWS, and described in much of this book. Service infrastructures are essentially custom web services “in the cloud.” These can be used individually or composited together to deliver a web application or do batch processing. For example, Amazon offers servers, storage, databases, queuing/messaging, payment processing, and more. Every one of these web services is a unique and custom solution. Storage using S3 uses the S3 protocol and storage mechanisms. The AWS SQS queuing service uses its own nonstandard custom protocol and message format. The same goes for SimpleDB, their database service. These services were designed in a custom manner to allow Amazon to scale to 50,000+ servers and thousands of products. They are being repurposed as publicly consumable web services that AWS customers consume for their own uses within their business models.

Cloudcenters

Most AWS competitors use this approach. ...