Software as a Service, SaaS
In SaaS, multiple users are provided access to the application software hosted on the server by the service provider. Users can access and interact with the cloud applications via the Internet, using interfaces such as web browsers, without the need to install any applications on their own systems. In Saas, software is provided as a service via the Internet and the service is priced on a pay-per-use basis. In Saas model, users do not manage or monitor the infrastructure components such as network, platform, operating system and storage devices. Users are only authorized to change configuration/structure settings specific to the application provided as a service.
Platform as a Service, PaaS
The service provider delivers the users a computing platform where they can develop and run their own applications using programming languages, software databases, services and tools provided by the service provider and also provides supplementary services. In PaaS model, users are not authorized to control or manage the servers, operating systems, storage spaces and other components that make up the platform infrastructure. Users’ authority is limited to adjustments related to the software transferred to the cloud and configuration settings of the platform the software runs on.
Infrastructure as a Service, IaaS
In IaaS model, users can configure processing, storage, networks and other fundamental computing resources required for running applications and install the operating system and applications required. Users are not fully authorized to manage and control the physical infrastructure. However, users can control the system at the level of storage and operating system and manage specific network components. IaaS model is referred to as”Hardware as a service, HaaS” in some sources.
Cloud computing infrastructure and business models are categorized based on being shared or specific to a single organization, being stored internally or externally, clients’ authority to interact with the architectural infrastructure of the service and capacity of customization to clients’ needs. These business models are assessed by users in terms of characteristics such as cost, level of user control on the system and scalability. Cloud computing should certainly be considered as a revolutionary innovation in terms of internet use, but as in all new systems, it contains challenges and disadvantages besides its advantages. Upon reviewing the infrastructure and service models briefly explained above, it can be claimed that the major problem in cloud computing is “data security”. It is a matter of concern for an organization or an individual to store their information and data in a third party service provider’s system. Therefore, the security risks arising out of these sharing and remotely accessed systems should be considered cautiously. In this way, each organization/individual can determine the most appropriate cloud infrastructure and service model for them and reconfigure their computing system affordably to comply with technology.