IT:AD:Azure:HowTo:Understand:The Difference Between Iaas Paas Saas

IT:AD:Azure:IaaS gives you a VM server in the cloud that you have complete control over.
You are responsible for managing everything from the OS configuration up to the app you are running.
Feels much like a typical on premises VM which you IT:AD:RDP into in order to manage.
Use cases:
- You need multiple apps running on a single machine, etc.

Consists of 2 components:
- your application files (source code, DLLs, etc.) and
  - a configuration file.
  * Together, these two elements will spin up a combination of Web Roles and Worker Roles to execute your application.
Azure takes care of the OS details for you – you focus on delivering the app.
- Typically Web Roles accept input and queue up an work in a Worker Role to process later, making the Web Role more responsive.
Roles:
- Web Role: an Azure VM pre-configured as a web server.
  - will automatically have your web/api app loaded by the time the server fully spins up.
  - Worker Roles: asynchronously process tasks the WebRole queued up.
  * You pre-configure the initial number of Web/Worker Roles and can Autoscale for dynamically adding/removing more as needed.

Azure Websites are easy, cheap, fast and appropriate for simple web applications that do not require complex scaling and data processing configuration.
You can use your IDE or configure source control (Git, GitHub, Bitbucket, CodePlex, TFS, and DropBox) to auto push to your Azure Website, letting Azure do the rest.
You can a deploy a database when provisioning your Azure Website through the Azure Management Portal.
- Just update your web site's web.config with your database's credentials

3rd party Services.
- Hosted on their premises or these days taking advantage of the benefits (eg: auto scaling) of IaaS.
* Azure Websites can also be served as SaaS:
- quickly deploy/minimally configure a custom or Wordpress/Drupal/etc site.

IaaS