A. There's a big push for cloud computing today. There are really three different types of cloud-based service:

  • Software as a Service (SaaS): Provides a complete software service solution. For example, Hotmail.
  • Platform as a Service (PaaS): Provides an application or database platform that can be used for custom applications and services. For example, Azure. Typically, you see PaaS used to create SaaS.
  • Infrastructure as a Service (IaaS): Provides an OS environment to be used for custom loads. For example, a hosted VM.

Each type offers different types of service and has different administrative and maintenance overheads for the client.

If you imagine the layers of management associated with any service, you can see the differing levels of management required. IaaS needs the most and PaaS or SaaS need the least. With an on-premise solution, you have to manage everything—the datacenter, physical hardware, and applications that provide a service. When you have IaaS, the provider takes care of all the hardware, storage, and virtualization, but you need to manage the guest OS and security. With PaaS, the guest OS is handled by the provider, and application developers can focus on the functionality of their applications. With SaaS, there's no management of any resource element, instead the only administration is things like adding new users or mailbox accounts.

On-Premise

IaaS

PaaS

SaaS

Applications

Applications

Applications

 

Development & Runtime Kernels

Development & Runtime Kernels

 

 

Databases

Databases

 

 

Security, Management, Load Balancing etc

Security, Management, Load Balancing etc

 

 

Local Servers, Storage

 

 

 

Virtualization

 

 

 

OS

 

 

 

Server Hardware

 

 

 

Datacenter infrastructure (Networking, Rack Space, HVAC etc)

 

 

 

 

On-Premise

IaaS

PaaS

SaaS

Applications

Applications

Applications

 

Development & Runtime Kernels

Development & Runtime Kernels

 

 

Databases

Databases

 

 

Security, Management, Load Balancing etc

Security, Management, Load Balancing etc

 

 

Local Servers, Storage

 

 

 

Virtualization

 

 

 

OS

 

 

 

Server Hardware

 

 

 

Datacenter infrastructure (Networking, Rack Space, HVAC etc)