When should one use the following: Amazon EC2, Goo

Question

I am asking this in very general sense. Both from cloud provider and cloud consumer's perspective. Also the question is not for any specific kind of application (in fact the intention is to know which type of applications/domains can fit into which of the cloud slab -SaaS PaaS IaaS).

My understanding so far is:

IaaS: Raw Hardware (Processors, Networks, Storage).

PaaS: OS, System Softwares, Development Framework, Virtual Machines.

SaaS: Software Applications.

It would be great if Stackoverflower's can share their understanding and experiences of cloud computing concept.

EDIT: Ok, I will put it in more specific way -

Amazon EC2: You don't have control over hardware layer. But you can take your choice of OS image, Dev Framework (.NET, J2EE, LAMP) and Application and put it on EC2 hardware. Can you deploy an applications built with Google App Engine or Azure on EC2?

Google App Engine: You don't have control over hardware and OS and you get a specific Dev Framework to build your application. Can you take any existing Java or Python application and port it to GAE? Or vice versa, can applications that were built on GAE be taken out of GAE and ported to any Application Server like Websphere or Weblogic?

Azure: You don't have control over hardware and OS and you get a specific Dev Framework to build your application. Can you take any existing .NET application and port it to Azure? Or vice versa, can applications that were built on Azure be taken out of Azure and ported to any Application Server like Biztalk?

Answer 1

My cloud experience is currently limited to Salesforce.com

For standard business operations and automation it provides a significant number of features that allow us to get apps up and running very quickly. We are particularly benefitting from the following:

• Security (Administrators can control access to objects and fields)
• Workflow & Approvals
• Automatic UI generation
• Built in reporting and dashboards
• Entire system (including our custom changes) is accessible via web services
• Ability to make the data in the system available through public sites (e.g. eCommerce)
• Large library of third party apps to solve standard problems

The platform does NOT solve every problem.

I would not use the platform to model a nuclear power station or build the next twitter.