IaaS vs. SaaS

By Ann Steffora Mutschler
There has been a lot of confusion about what kind of cloud-based service the EDA industry offers. Here are two different business models.

Infrastructure as a service (IaaS)
In this most basic cloud service model, cloud providers offer computers – as physical or more often as virtual machines, raw (block) storage, firewalls , load balancers, and networks. IaaS providers supply these resources on demand from their large pools installed in data centers. Local area networks including IP addresses are part of the offer. For the wide area connectivity, the Internet can be used or – in carrier clouds – dedicated virtual private networks can be configured.

To deploy their applications, cloud users then install operating system images on the machines as well as their application software. In this model, it is the cloud user who is responsible for patching and maintaining the operating systems and application software. Cloud providers typically bill IaaS services on a utility computing basis. The cost will reflect the amount of resources allocated and consumed.

Infrastructure-as-a-Service or IaaS Cloud is a platform through which businesses can avail equipment in the form of hardware, servers, storage space etc. at pay-per-use service.

Software as a service (SaaS)
In this model, cloud providers install and operate application software in the cloud and cloud users access the software from cloud clients. The cloud users do not manage the cloud infrastructure and platform on which the application is running. This eliminates the need to install and run the application on the cloud user’s own computers simplifying maintenance and support. What makes a cloud application different from other applications is its elasticity. This can be achieved by cloning tasks onto multiple virtual machines at run-time to meet the changing work demand. Load balancers distribute the work over the set of virtual machines. This process is transparent to the cloud user who sees only a single access point. To accommodate a large number of cloud users, cloud applications can be multitenant, that is, any machine serves more than one cloud user organization. It is common to refer to special types of cloud based application software with a similar naming convention: desktop as a service, business process as a service, Test Environment as a Service, communication as a service.

The pricing model for SaaS applications is typically a monthly or yearly flat fee per user.

Source: Wikipedia