What are IaaS, PaaS, and SaaS in cloud computing?

"Cloud service" has become a household word now. If you don't know the difference between PaaS, IaaS and SaaS, it's okay because many people don't know.

"Cloud" is actually a metaphor for the Internet. "Cloud computing" is actually using the Internet to access applications, data, or services stored or running on remote servers . Any company that uses Internet-based methods for computing, storage, and development can technically be called a cloud company. However, not all cloud companies are the same. Not everyone is a CTO, so sometimes it can be a headache to see some of the words behind cloud technology.

Any company that provides services on the Internet can be called a cloud computing company. In fact, cloud computing is divided into several layers, namely Infrastructure-as-a-Service, Platform-as-a-Service, and Software-as-a-Service. Infrastructure is at the bottom, platform is in the middle, and software is at the top. Other "soft" layers can be added on top of these layers.

1.IaaS: Infrastructure-as-a-Service

The first layer is called IaaS, sometimes also called Hardware-as-a-Service. A few years ago, if you wanted to run some enterprise applications in your office or company website, you needed to buy a server or other expensive hardware to control the local application and get your business running.

But now with IaaS, you can outsource the hardware to somewhere else. IaaS companies will provide off-site servers, storage, and network hardware that you can rent. This saves maintenance costs and office space, and companies can use this hardware to run their applications at any time.

Some of the big IaaS companies include Amazon, Microsoft, VMWare, Rackspace and Red Hat. However, these companies have their own expertise. For example, Amazon and Microsoft provide you with more than just IaaS. They also rent out their computing power to you to host your website.

2.PaaS: Platform-as-a-Service

The second layer above the IaaS layer is the PaaS (Platform as a Service) layer. Sometimes it is also called middleware. All your company's development can be done at this layer, saving time and resources.

PaaS companies provide a variety of solutions for developing and distributing applications online, such as virtual servers and operating systems. This saves you money on hardware and makes collaboration between distributed studios easier. Web application management, application design, application virtual hosting, storage, security, and application development collaboration tools are all included.

Some large PaaS providers include Google App Engine, Microsoft Azure, Force.com, Heroku, and Engine Yard.

Recent startups include AppFog, Mendix and Standing Cloud.

3.SaaS: Software-as-a-Service

The third layer is the so-called SaaS. This layer is the layer that you come into contact with every day in your life, and most of them are accessed through a web browser. Any application on a remote server can be run through the network, which is SaaS.

The services you consume are completely accessed from the web such as Netflix, MOG, Google Apps, Box.NET, Dropbox or Apple's iCloud. Although these web services are used for business and entertainment or both, they are also part of cloud technology.

Some SaaS applications used for business include Citrix's GoToMeeting, Cisco's WebEx, Salesforce's CRM, ADP, Workday, and SuccessFactors.

According to the most commonly used and authoritative definition of NIST (National Institute of Standards and Technology), cloud computing is mainly divided into three service models, and this three-tier division is mainly based on the perspective of user experience:

Software as a Service, or SaaS for short, is a layer that provides applications as services to customers.

Platform as a Service, Platform as a Service, referred to as PaaS, the role of this layer is to provide a development platform as a service to users.

Infrastructure as a Service, referred to as IaaS, is a layer that provides virtual machines or other resources as services to users.

1. SaaS

Through the SaaS model, users can directly use applications running on the cloud by simply connecting to the Internet and using a browser, without having to worry about trivial matters such as installation, and avoiding the high initial investment in software and hardware. SaaS is mainly aimed at ordinary users.

Major products include: Salesforce Sales Cloud, Google Apps, Zimbra, Zoho and IBM Lotus Live, etc.

When it comes to the functions of SaaS, it can also be considered that in order to implement SaaS services, what functions do suppliers need to complete? There are mainly four aspects:

1. Access anytime, anywhere: Users can access this SaaS service at any time or any place as long as they are connected to the Internet.

2. Support open protocols : By supporting open protocols (such as HTML4/5), it can be convenient for users to use.

3. Security assurance: SaaS providers need to provide certain security mechanisms, not only to ensure that user data stored in the cloud is absolutely safe, but also to implement certain security mechanisms on the client side (such as HTTPS) to protect users.

4. Multi-Tenant Mechanism: The multi-tenant mechanism can not only support a large user base more economically, but also provide a certain degree of customizability to meet the special needs of users.

2. PaaS

Through the PaaS model, users can easily write applications on a development platform that includes SDK, documents and test environment , and no matter when deploying or running, users do not need to worry about the management of resources such as servers, operating systems, networks and storage. These tedious tasks are handled by PaaS providers. In addition, the integration rate of PaaS is amazing. For example, a server running Google App Engine can support thousands of applications. In other words, PaaS is very economical. The main users of PaaS are developers.

The main products include: Google App Engine, heroku and Windows Azure Platform, etc.

In order to support the operation of the entire PaaS platform, what functions does the supplier need to provide? There are four main functions:

1. Friendly development environment: By providing tools such as SDK and IDE, users can easily develop and test applications locally.

2. Rich services: The PaaS platform provides a variety of services to upper-level applications in the form of APIs.

3. Automatic resource scheduling: This is the scalable feature, which will not only optimize system resources, but also automatically adjust resources to help applications running on them better cope with sudden traffic.

4. Fine-grained management and monitoring: PaaS can provide application-layer management and monitoring. For example, it can observe the application's running conditions and specific values ​​(such as throughput and response time) to better measure the application's running status, and can better bill by accurately measuring the resources consumed by the application.

3. IaaS model

Through the IaaS model, users can obtain the virtual machines or storage resources they need from suppliers to load related applications, and the tedious management of these infrastructures will be handled by the IaaS supplier. IaaS can support a wide range of applications through virtual machines. The main users of IaaS are system administrators.

The main products include: Amazon EC2, Linode, Joyent, Rackspace, IBM Blue Cloud and Cisco UCS, etc.

Basic functions of IaaS:

1. Resource abstraction: Using resource abstraction methods (for example, resource pools) can better schedule and manage physical resources.

2. Resource monitoring: By monitoring resources, the efficient operation of the infrastructure can be ensured.

3. Load management: Through load management, applications deployed on the infrastructure can not only better cope with emergencies, but also make better use of system resources.

4. Data management: For cloud computing, data integrity, reliability and manageability are basic requirements for IaaS.

5. Resource deployment: that is, automating the entire resource process from creation to use.

6. Security Management: The main goal of IaaS security management is to ensure that the infrastructure and the resources it provides can be accessed and used legally.

7. Billing management: Detailed billing management enables users to use resources more flexibly.

The main function of PaaS is to provide a development and operation platform as a service to users, while the main function of IaaS is to provide virtual machines or other resources as a service to users. Next, we will compare PaaS and IaaS in seven aspects:

1. Development environment: PaaS basically provides developers with a complete development and testing environment including IDE , while for IaaS, users mainly continue to use the development environment they are familiar with. However, because the previous development environment lacks integration with the cloud, it is not very convenient to use.

2. Supported applications: Because IaaS mainly provides virtual machines, and ordinary virtual machines can support multiple operating systems, the range of applications supported by IaaS is very wide.

However, it is not an easy task to enable an application to run on a PaaS platform, because not only do you need to ensure that the application is based on a language supported by the platform, but you also need to ensure that the application can only call APIs supported by the platform. If the application calls an API that is not supported by the platform, then the application needs to be modified.

3. Open standards: Although many IaaS platforms have certain private functions, the existence of protocols such as OVF has enabled IaaS to steadily advance in terms of cross-platform and avoiding vendor lock-in. However, the situation of PaaS platforms is not optimistic, because both Google's App Engine and Salesforce's Force.com have certain private APIs.

4. Scalability : The PaaS platform automatically adjusts resources to help applications running on it better cope with sudden traffic, while the IaaS platform requires developers to manually adjust resources to cope with it.

5. Integration rate and economy: The integration rate of PaaS platform is very high. For example, Google App Engine, the representative of PaaS, can carry thousands of applications on a single server, while the integration rate of ordinary IaaS platform will not exceed 100 at most, and is generally around 10, making IaaS less economical than PaaS.

6. Billing and supervision: Because the PaaS platform not only reaches the operating system level that the IaaS platform can achieve in terms of billing and supervision, such as CPU and memory usage, but also the application level, such as the application's response time or the number of transactions consumed by the application, which will improve the accuracy of billing and management.

7. Learning difficulty: Because developing and managing applications on IaaS is closer to existing methods, while development on PaaS may require learning a new language or a new framework, IaaS is easier to learn.

In general, IaaS, PaaS and SaaS are the three levels of cloud service provision. The most basic is IaaS, the middle is PaaS, and the most intuitive is SaaS. This article simply explains the three concepts of IaaS, PaaS and SaaS, and I hope it can be of some help to you.