A cloud contains various services such as storage devices, virtual networks, platforms, applications etc. The user might request the cloud for any service. Cloud just cannot send all services it is holding for every single request. For an instance, let us assume that the user might request just for a software or for a platform to develop an application or the storage space to store the data. Depending on such requests, services of the cloud are broadly categorized into four models. They are:
- Software-as-a-Service (SaaS)
- Platform-as-a-Service (PaaS)
- Infrastructure-as-a-Service (IaaS)
- Network-as-a-Service (NaaS)
Software-as-a-Service (SaaS):
In SaaS service model, the user requests for a software as a service. Some software are available at no cost, while for other software user need to pay. The software is sent to the user via the Internet and is retrieved on the user’s hardware device. Once, the user gets the service from the cloud, it is ready to use. Cloud server is responsible for the maintenance of the softwares. Users need not worry about the updates, backups and licensing fees.
Examples for Software-as-a-Service (SaaS) is the Gmail, yahoo, Facebook, certain banking services, etc.
Platform-as-a-Service (PaaS):
In PaaS service model, the user requests for a platform as a service. For any IT company to built an application, they need aplatform or an environment. For a small and medium scale companies, purchasing the environment might be expensive. Also another drawback is that the same platform might not be useful for other application developments. In this situation, PaaS is cost effective for the company to get the software, pay for it untill it is used and can stop using the service without paying for that service. In any case, the software is always available on the cloud if you need it in future. There are also chances of utilizing free platforms which are available on public clouds. In this way, users get the platforms they need on cloud at lower price and no tedious work of managing it as providers are solely responsible for the maintenance.
Examples for Platform-as-a-Service are some operating systems and programming languages.
Infrastructure-as-as-Service (IaaS):
This model can be simplified as infrastructure is sent to user as a service. Infrastructure comprises all software and hardware services available on cloud. User may request for any service. It may be a software or a platform or a server. Any application developed by a company needs a server to execute the developed application. For this reason, a user can request the cloud for a server. This server is sent to the user through Internet to the user’s end device.
Example of Infrastructure-as-a-Service are some hosting firewalls.
Network-as-a-Service (NaaS):
This service model is very rare in real time. In this service model, users make use of the virtual networks, which are already built and deployed on the cloud. It is comfortable for the user to use the existing network than building a new one. As in every other model, the service (network) is monitored by the service provider. The owners of the private clouds deploy the networks that work for them. They request the network as a service every time they need it.
Examples for Network-as-a-service are some virtual private networks (VPNs), mobile virtual network operators (MVNOs).
Cloud computing, thus, provides various services to the users.
