Cloud computing services
IaaS (Infrastructure-as-a-Service), PaaS (Platform-as-a-Service), and SaaS (Software-as-a-Service) are the three most common models of cloud services, and it's not uncommon for an organization to use all three.
SaaS (Software-as-a-Service)
SaaS also known as cloud-based software or cloud applications is application software that's hosted in the cloud and that you access and use via a web browser, a dedicated desktop client, or an API that integrates with your desktop or mobile operating system. In most cases, SaaS users pay a monthly or annual subscription fee; some may offer 'pay-as-you-go' pricing based on your actual usage.
In addition to the cost savings, time-to-value, and scalability benefits of cloud, SaaS offers the following:
- Automatic Upgrades: With SaaS, you take benefit of new features as soon as the provider adds them, without having to coordinate an on-premises upgrade.
- Security from Data Loss: Because your application data is in the cloud, with the application, you don't lose data if your device crashes or breaks.
SaaS is the primary delivery model for most commercial software today - there are hundreds of thousands of SaaS solutions existing, from the most resolute industry and departmental applications, to powerful enterprise software database and AI (Artificial Intelligence) software.
PaaS (Platform-as-a-Service)
PaaS provides software developers with on-demand platform - hardware, complete software stack, infrastructure, and even development tools - for running, developing, and managing applications without the cost, difficulty, and obstinacy of maintaining that platform on-premises.
With PaaS, the cloud provider hosts everything - servers, networks, storage, operating system software, middleware, databases-at their data centre. Developers simply pick from a menu to 'spin up' servers and environments they need to run, build, test, deploy, maintain, update, and scale applications.
Today, PaaS is often built around containers, a virtualized compute model one step removed from virtual servers. Containers virtualized the operating system, enabling developers to package the application with only the operating system services it needs to run on any platform, without modification and without need for middleware.
IaaS (Infrastructure-as-a-Service)
IaaS provides on-demand access to fundamental computing resources-physical and virtual servers, networking, and storage-over the internet on a pay-as-you-go basis. IaaS enables end users to scale and shrink resources on an as-needed basis, reducing the need for high, up-front capital expenditures or unnecessary on-premises or 'owned' infrastructure and for overbuying resources to accommodate periodic spikes in usage.
In distinction to SaaS and PaaS (and even newer PaaS computing models such as containers and serverless), IaaS provides the users with the lowest-level control of computing resources in the cloud.
IaaS was the most popular cloud computing model when it emerged in the early 2010s. While it remains the cloud model for many types of workloads, use of SaaS and PaaS is growing at a much faster rate.