Matching the 3-Tier Application model to the Cloud

For those Companies who already use the Cloud, the Terms IaaS, PaaS & SaaS are understood as 1+1. For decades where Software System have been installed in a local Datacentre the 3-Tier Application model was the norm. Consisting of 3 Tiers for the Application, data storage in a database, Business logic Layer holding the main source code e.g. in Java or C# or any other programming language and a Presentation Layer for the Business User to interact with. While the Cloud essentially takes the local Datacentre to the Software Vendor Datacentre location and the Internet, some new terms emerged: SaaS,IaaS,Paas. For reference, these new “Cloud” terms can be matched to the “classic” 3-Tier Application model:
image