In this Post , I will try to Define the most commonly used Cloud Delivery Models in the Oracle Context. Generally , SaaS, PaaS ,IaaS, IPaaS terms are used by any Cloud Vendor .
SaaS Means Software as a Service . In this model customer get an out of box functionality of a particular product .
for example if you take Oracle ERP Cloud Application , you get certain products like Supply Chain , Financials and HCM with out of box features as a part of it . Usually with any of these SaaS product's the customisation scope is limited to zero depending on the vendor and the product however the personalization options varies to the maximum possible extent. Further more, Upgrades , Maintenance , Patches, Refreshes,Security will be automatically taken care by the vendor it self. So Practically you wont need any administrators to perform the same. In Short this model is to consume what is available.
(e.g.,Vendors Oracle Taleo, SalesForce.com,WorkDay )
PaaS Means Platform as a service . In This Model customer gets a platform to develop ,deploy and maintain their custom applications along with DBaaS on Cloud . This Specifically suits for the customers where the SaaS out of box features are not sufficient to carry of their business operations. we can extend SaaS using PaaS offering.
In short you can build new things as per your requirements with this mode and extend the SaaS.
(Eg : Oracle Java Cloud Service, Google App Engine)
IaaS Means Infrastructure as a service . In this Model customer will manage the key Areas like Servers , Networking , Computing , messaging , Storage and so on ..
In short you can host your custom applications and take the full control of the same.
(e.g., Oracle Cloud Infrastructure, Amazon Web Services,Azure Cloud Services)
IPaaS Means Integration Platform as a service . This Basically offers you to provision quickly, easily develop and deploy your APIs and integration projects, and get real-time analytics. Customer get's lots of cloud and on-premise adaptors for rapid integrations.
Eg Vendors : OIC, SOACS, Dell Boomi
Hope this Post helps you.
Please leave your comments in case of any questions.