As cloud computing services continue to evolve, the business model of software changes and the National Institute of Standards NIST has proposed three standard models, namely the well-known Software as a Service (SaaS), Platform as a Service (PaaS), Infrastructure as a Service (IaaS).
From the previous section on cloud computing, those that provide virtual machine services, where users install their own operating systems and applications, belong to infrastructure construction, which we call IaaS services. Those that provide operating system + common database services, where users install their applications, are called PaaS services. Finally, those that provide application-based services are called SaaS services. See Figure 2-12. They are often described as layers in the stack: infrastructure, platform, and software-as-a-service, with no correlation between them. Thus, for example, one can provide SaaS implemented on a physical machine (bare metal) without using the underlying PaaS or IaaS layer; conversely, one can run a program on IaaS and access it directly without packaging it SaaS.
Figure 2-12 Cloud_computing_layers[1]
The service-oriented architecture proposes Everything as a Service (EaaS or XaaS), as detailed in Figure 2-13.
Figure 2-12 Everything as a service
1 Infrastructure as a Service (IaaS)
The NIST(National Institute of Standards and Technology) definition of cloud computing describes IaaS as “where the consumer can deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, and deployed applications; and possibly limited control of select networking components (e.g., host firewalls).”
“Infrastructure as a service” (IaaS) refers to online services that provide high-level API used to abstract various low-level details of underlying network infrastructure like physical computing resources, location, data partitioning, scaling, security, backup, etc. A hypervisor runs the virtual machines as guests. Pools of hypervisors within the cloud operational system can support large numbers of virtual machines and the ability to scale services up and down according to customers’ varying requirements. Linux containers run in isolated partitions of a single Linux kernel running directly on the physical hardware. Linux cgroups and namespaces are the underlying Linux kernel technologies used to isolate, secure, and manage the containers. Containerisation offers higher performance than virtualization because there is no hypervisor overhead. IaaS clouds often offer additional resources such as a virtual-machine disk-image library, raw block storage, file or object storage, firewalls, load balancers, IP addresses, virtual local area networks (VLANs), and software bundles.[2]
IaaS-cloud providers supply these resources on-demand from their large pools of equipment installed in data centers. For wide-area connectivity, customers can use either the Internet or carrier clouds (dedicated virtual private networks). To deploy their applications, cloud users install operating-system images and their application software on the cloud infrastructure. In this model, the cloud user patches and maintains the operating systems and the application software. Cloud providers typically bill IaaS services on a utility computing basis: cost reflects the allocated and consumed resources.[3]
2 Platform as a Service (PaaS)
The NIST’s definition of cloud computing defines a Platform as a Service: The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages, libraries, services, and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure, including network, servers, operating systems, or storage, but controls the deployed applications and possibly configuration settings for the application-hosting environment.[4]
PaaS vendors offer a development environment to application developers. The provider typically develops a toolkit and standards for development and channels for distribution and payment. Cloud providers deliver a computing platform in the PaaS models, including operating systems, programming-language execution environments, databases, and web servers. Application developers develop and run their software on a cloud platform instead of directly buying and managing the underlying hardware and software layers. With some PaaS, the underlying computer and storage resources scale automatically to match application demand so that the cloud user does not have to allocate resources manually.[5]
With the advent of container technology for PaaS services, users can easily and quickly deploy applications.
3 Software as a Service (SaaS)
The NIST(National Institute of Standards and Technology) definition of cloud computing defines software as a service as: “The capability provided to the consumer is to use the provider’s applications running on a cloud infrastructure. The applications are accessible from various client devices through either a thin client interface, such as a web browser (e.g., web-based email), or a program interface. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings.”[6]
In the software as a service (SaaS) model, users access application software and databases. Cloud providers manage the infrastructure and platforms that run the applications. SaaS is sometimes called “on-demand software” and is usually priced on a pay-per-use basis or using a subscription fee. In the SaaS model, cloud providers install and operate application software in the cloud, and cloud users access the software from cloud clients. Cloud users do not manage the cloud infrastructure and platform where the application runs. This eliminates the need to install and run the application on the cloud user’s computers, simplifying maintenance and support. Cloud applications differ from other applications in their scalability—which can be achieved by cloning tasks onto multiple virtual machines at run-time to meet changing work demands. Load balancers distribute the work over the set of virtual machines. This process is transparent to the cloud user, who sees only a single access point. To accommodate a large number of cloud users, cloud applications can be multitenant, meaning that any machine may serve more than one cloud-user organization.[7]
The pricing model for SaaS applications is usually a fixed cost per user per month or year, so if users are added or removed at any time, the price becomes scalable and adjustable. It may also be accessible.
The advantage of SaaS is that it gives organizations the potential to reduce IT operational costs by outsourcing hardware and software maintenance and support to a cloud provider. This allows organizations to reallocate IT operating costs from hardware/software expenditures and personnel expenses to achieve other goals. In addition, using centrally hosted applications, updates can be released without the need for users to install new software.
The disadvantage of SaaS is that the user’s data is stored on the cloud provider’s servers. Therefore, there is a possibility of unauthorized access to the data, resulting in data theft.
4 Function as a Service (SaaS)
Function as a Service (FaaS) is another type of cloud computing service that provides a platform that allows customers to develop, run and manage application functionality without the need to build and maintain the infrastructure typically associated with developing and launching applications. Building applications following this model is one way to achieve a “serverless” architecture, commonly used when building microservice applications.
AWS Lambda was the first FaaS offering from a large public cloud provider, followed by Google Cloud Functions, Microsoft Azure Functions, IBM / Apache’s Open Whisk (open source system) in 2016, and Oracle Cloud Fn in 2017 (open source system).
In smart manufacturing applications, SaaS, PaaS, IaaS, and FaaS can be provided according to the needs and resources of different enterprises.
In general, for companies that provide industrial control infrastructure hardware, PaaS services are provided to facilitate industry integrators to develop industry-specific applications. As a result, they can facilitate the sales of their hardware products.
For companies that provide intelligent manufacturing services for niche industries, generally speaking, they will provide SaaS. It can provide users of the industry with smart manufacturing software services for the niche industry, including C2M (Consumer to Manufacturing) services, intelligent machine services, etc. This can help users save a lot of time and human resources.
Figure 2-14 Everything as a Service System Schematic
[1] from en.wikipedia.rog/wiki/File:Cloud_computing_layers.pnp, Oct 18, 2021
[2] from Wikipedia.org, Cloud Computing, Oct 18,2021
[3] from Wikipedia.org, Cloud Computing, Oct 18,2021
[4] from Wikipedia.org, Cloud Computing, Oct 18,2021
[5] from Wikipedia.org, Cloud Computing, Oct 18,2021
[6] from Wikipedia.org, Cloud Computing, Oct 18,2021
[7] from Wikipedia.org, Cloud Computing, Oct 18,2021