In a previous post, “What The Heck Is Cloud Computing?” I broke the cloud up into three categories. however I do not think I did a good job of delineating these categories with examples. So here goes:
IaaS: Infrastructure as a Service
- Storage: Amazon S3 (BLOB storage), Amazon SDB (Table Storage), Microsoft Windows Azure Simple Data Storage (both table and BLOB)
- Database: Microsoft SQL Azure, Amazon RDS
- Virtual servers: Amazon EC2
PaaS: Platform as a Service
SaaS: Software as a Service
- Pretty much every application accessed through a website. Pick your favorite webmail or photo hosting site for instance.
- But some stand out as more fully featured applications run from the browser more than as mere websites: Microsoft Outlook Web Access, Google Docs, Microsoft Office Web Apps.
- “…virtual machine instances, storage, and computation at pay-as-you-go utility pricing…”
Platform as a Service
- “…which hide machine instances behind higher-level APIs”
Cloud-based end-user applications
- “Any web application is a cloud application in the sense that it resides in the cloud. Google, Amazon, Facebook, twitter, flickr, and virtually every other Web 2.0 application is a cloud application in this sense. However, it seems to me that people use the term "cloud" more specifically in describing web applications that were formerly delivered locally on a PC, like spreadsheets, word processing, databases, and even email”
where these labels pretty much correspond 1 to 1 to the ones above.
I hope this clarifies things a bit.
This is part 2 of a series:
- What The Heck Is Cloud Computing?
- <this post>
- What The Heck Is Cloud Computing? – Another re-look, with Pretty Pictures