22 May Types of Cloud Computing Which are Currently in Use
Cloud Computing providers typically centre on one type of cloud functionality provisioning: Infrastructure, Platform or Software / Application, though there is potentially no restriction to offer multiple types at the same time, which can often be observed in PaaS (Platform as a Service) providers which offer specific applications too, such as Google App Engine in combination with Google Docs. Due to this combinatorial capability, these types are also often referred to as “components”.
Literature and publications typically differ slightly in the terminologies applied. This is mostly due to the fact that some application areas overlap and are therefore difficult to distinguish. As an example, platforms typically have to provide access to resources indirectly, and thus are sometimes confused with infrastructures. Additionally, more popular terms have been introduced in less technologically centered publications.
The following list identifies the main types of clouds (currently in use):
(Cloud) Infrastructure as a Service (IaaS) also referred to as Resource Clouds, provide (managed and scalable) resources as services to the user – in other words, they basically provide enhanced virtualization capabilities. Accordingly, different resources may be provided via a service interface: Data & Storage Clouds deal with reliable access to data of potentially dynamic size, weighing resource usage with access requirements and / or quality definition.
Examples: Amazon S3, SQL Azure.
Compute Clouds provide access to computational resources, i.e. CPUs. So far, such low-level resources cannot really be exploited on their own, so that they are typically exposed as part of a “virtualized environment” (not to be mixed with PaaS below), i.e. hypervisors. Compute Cloud Providers therefore typically offer the capability to provide computing resources (i.e. raw access to resources unlike PaaS that offer full software stacks to develop and build applications), typically virtualized, in which to execute cloudified services and applications. IaaS (Infrastructure as a Service) offers additional capabilities over a simple compute service.
Examples: Amazon EC2, Zimory, Elastichosts.
(Cloud) Platform as a Service (PaaS), provide computational resources via a platform upon which applications and services can be developed and hosted. PaaS typically makes use of dedicated APIs to control the behavior of a server hosting engine which executes and replicates the execution according to user requests (e.g. access rate). As each provider exposes his / her own API according to the respective key capabilities, applications developed for one specific cloud provider cannot be moved to another cloud host – there are however attempts to extend generic programming models with cloud capabilities (such as MS Azure).
Examples: Force.com, Google App Engine, Windows Azure (Platform).
(Clouds) Software as a Service (SaaS), also sometimes referred to as Service or Application Clouds are offering implementations of specific business functions and business processes that are provided with specific cloud capabilities, i.e. they provide applications / services using a cloud infrastructure or platform, rather than providing cloud features them. Often, kind of standard application software functionality is offered within a cloud.
Examples: Google Docs, Salesforce CRM, SAP Business by Design.
Overall, Cloud Computing is not restricted to Infrastructure / Platform / Software as a Service system, even though it gives enhanced capabilities which act as (vertical) enablers to these systems. As such, SaaS can be considered specific “usage patterns” for cloud systems which relate to models already approached by Grid, Web Services etc. Cloud systems are a promising way to implement these models and extend them further.
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You can also read 7 Advantages of Cloud Computing here.