Yesterday, we introduced the five essential characteristics of cloud computing. Today, we will continue with the definition of the cloud and introduce the three service models of cloud services.
Contents
Service Models
Cloud service models are primarily divided into three types.
- Infrastructure as a Service (IaaS)
- Platform as a Service (PaaS)
- Software as a Service (SaaS)
In the following introduction, we will refer to them as IaaS, PaaS, and SaaS. I will quote here...the translation from the National Chung Hsing University Senior Learning Network:
IaaS
"Infrastructure as a Service" (IaaS) is a collection of virtualized hardware resources and related management functions. It uses virtualization technology to abstract resources such as computing, storage, and networking, achieving internal process automation and resource management optimization to provide dynamic and flexible infrastructure services externally. Consumers at this level use "basic computing resources" such as processing power, storage space, network components, or middleware. They can also control operating systems, storage, deployed applications, firewalls, and load balancers, but they do not control the underlying cloud infrastructure; instead, they directly enjoy the convenient services provided by IaaS.
Taking major cloud service providers as examples, the following services all fall under the scope of IaaS:
- AWS: EC2, VPC
- GCP: GCE
- Azure: Virtual Machines, Block Storage
PaaS
"Platform as a Service" (PaaS) provides an environment for the development, operation, management, and monitoring of cloud applications. It can be described as optimized "cloud middleware." A well-designed platform layer can meet cloud requirements for scalability, availability, and security. Consumers at this level can use development tools provided by the platform provider to build their own applications on the cloud architecture. While they can control the environment in which the applications run (and have some control over the host), they do not control the operating system, hardware, or the underlying network infrastructure.
The Kubernetes you often hear about is generally categorized as PaaS (specifically Container as a Service), as are various managed services like databases.
Taking major cloud service providers as examples, the following services all fall under the scope of PaaS:
- AWS: EKS, RDS
- GCP: Google Kubernetes Engine, Cloud SQL
- Azure: AKS, SQL
SaaS
"Software as a Service" (SaaS) is a collection of software applications built on the resources provided by the infrastructure layer and the environment provided by the platform layer, delivered to users via the internet. Applications at this layer allow users to access services through various internet-connected devices (endpoints) simply by opening a browser or an internet interface. Users no longer need to worry about software installation or upgrades, nor do they need to purchase software licenses upfront; instead, they pay based on actual usage. For application developers, they can easily deploy and upgrade software without needing to manage or control the underlying cloud infrastructure, such as networks, servers, operating systems, or storage.
Basically, most cloud services used by general users belong to SaaS. Any software service accessed through an internet interface generally falls within the scope of SaaS.
Here are a few examples of SaaS:
- Gmail
- Google Drive
- One Drive
These are the three service models of cloud services.
Summary
In this post, we introduced the three service models of cloud services. Compared to the essential characteristics, these are more concrete and allow for many practical examples.
Tomorrow, we will introduce cloud service deployment models. Stay tuned!
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