Cloud Computing Platforms consist of different Services (if the Application is built with SOA – Service Oriented Architectures) or Roles. A Role is not necessary a Service, as a Role might consist of multiple Services. Let’s look at a Web Shop: a Role in the context of a Webshop would rather be the Shopping Cart. But the Shopping Cart itself would consist of more services. This is why we can talk about “Application Role Separation”. If we talk about SOA, everything is divided in the technical part. With ARS (Application Role Separation) we can have a “SOA of SOA” by adding services that belong to a specific domain to a Role.
However, Application Role Separation gives us more possibilities. If we have a serious issue such as an outage of the datacenter, we can shut down or run a specific role at lower priority. Back to the context of a webshop, this would mean that the Role “Comments” can be disabled. The “Comment” Role itself would again consist of different Services such as the rating (Stars) and the Read Comments and Write Comments Service.
Roles for the Webshop could be the following:

• Webshop to read data
• Shopping Cart
• Order
• Background Services (Business Intelligence and Statistics, Mail Processing, Order Processing Workflow)

Architecture for a Webshop