Introduction

Windows Azure is the paradigm of the Platform-as-a-Service model (PaaS) of cloud computing. A hosted service can be developed and deployed to any of several Windows Azure data centers located across the World. A service hosted in Windows Azure can leverage the high scalability and reduced administrative benefits of the PaaS model.

A hosted service is an administrative and security boundary. Administrative because applications in it are packaged and deployed as a whole, and security because the hosted service is accessible from outside only through load-balanced endpoints. An application deployed into a hosted service comprises a set of roles, instances of which are deployed to virtual machines (VM) to implement service functionality.

A role is the scalability unit of a hosted service in that it provides vertical scaling, through the use of a larger VM size for instances of the role, and horizontal scaling through the elastic deployment of a workload-dependent number of instances...