Owning software is very expensive. For example, a ₹50 lakh software running on a ₹1 lakh computer is a common place. As with hardware, owning software is the current tradition across individuals and business houses. Often the usage of a specific software package does not exceed a couple of hours of usage per week.
In this situation, it would be economically worthwhile to pay per hour of usage. This would also free the user from the botherance of maintenance, upgradation, backup etc.
This is exactly what is advocated by SaaS.
Software As A Service (SaaS) is a software delivery model and involves customers to pay for any software per unit time of usage, with the price reflecting market place supply and demand.
In this context, SaaS makes a case for pay per usage of software rather than owning software for use.
As we can see, SaaS shifts “ownership” of a software from a customer to a service provider. Software owner provides maintenance, daily technical operation and support for the software.
Services are provided to the client on the amount of usage basis.
The service provider is a vendor who hosts the software and lets the users execute on-demand charges per usage units. It also shifts the responsibility for hardware and software management from customer to the provider. The cost of providing software services reduces as more and more subscribe to the service.
It makes the software accessible to a large number of customers who cannot afford to purchase the software outright.
If we compare SaaS to SOA, we can observe that SaaS is a software delivery model, whereas SOA is a software construction model. Despite significant differences, both SOA and SaaS espouse closely related architecture models. SaaS and SOA complement each other. SaaS helps to offer components for SOA to use. SOA helps to quickly realize SaaS. Also, the main enabler of SaaS and SOA are the internet and web services technologies.
