We write reports in online documents, photos are automatically saved online, and we watch videos through streaming—we have already entrusted much of our lives to the “cloud.” What exactly is the cloud, what types are there, and what is convenient or risky about it? In this lesson, we study this system that has become the foundation of the information society.
What Is Cloud Computing?
Cloud computing is a model in which information resources such as servers, storage, and software are not owned by users but are used as services through the Internet. Its opposite is on-premises, which refers to the traditional model of installing and operating equipment at a company or home. The actual cloud consists of huge data centers operated by providers around the world. From the user's perspective, it is “computing resources beyond the cloud that users do not need to know the location of,” which is said to be the origin of the name. Many cloud services use a pay-as-you-go pricing system, in which users pay according to the amount they use.
Three Service Categories — IaaS, PaaS, and SaaS
Cloud services are classified into three categories according to “how much of the system the provider supplies.” ①IaaS (Infrastructure as a Service: ee-ahss / eye-ahss): Provides infrastructure such as virtual servers, storage, and networks. Because users build everything above the operating system, it offers the greatest freedom. ②PaaS (Platform as a Service: pass): Provides the platform needed to develop and run applications, including the operating system and databases. Developers can focus on the program itself. ③SaaS (Software as a Service: sass): Provides the completed software (application) itself. Many cloud services used by general users, such as webmail, online office software, and online storage, are SaaS. Lower layers offer greater freedom but require more work, while higher layers are easier to use but allow less customization.
Service Models — Public and Private
Cloud services are also classified according to their range of availability. A public cloud is a general-purpose cloud shared by an unspecified number of users, and it can be started at low cost. A private cloud is built exclusively for a particular company or organization. Although it costs more, security requirements and unique settings can be managed in detail. There is also a model called a hybrid cloud, which combines the two and on-premises systems. Highly confidential data may be kept inside the company, while processing with large fluctuations may use a public cloud.
Benefits and Risks of the Cloud
The benefits of the cloud are as follows. ① Initial costs can be reduced, and capacity can be expanded or reduced immediately as needed (scalability). ② The provider can handle equipment purchase, maintenance, and updates. ③ Services can be used from anywhere with an Internet connection, and the cloud is well suited to collaborative editing by multiple people and backups for disasters (stored at data centers in remote locations). However, there are also risks. ① Failures and outages: If a failure occurs on the cloud provider's side, many services may become unavailable at the same time. ② Information leaks and configuration errors: Accidents involving leaks caused by incorrect public settings have occurred repeatedly. ③ Dependence (lock-in): Deep dependence on a particular provider can make switching difficult. ④ Services cannot be used without a communications environment. It is important to understand “what is entrusted, where it is entrusted, and how responsibility is shared,” rather than assuming that “entrusting it means it is safe.”
- Cloud = using information resources as services through the Internet without owning them. Its opposite is on-premises.
- IaaS = provides infrastructure / PaaS = provides the development and execution environment / SaaS = provides the application itself.
- Lower layers offer greater freedom but require more work. General users mainly use SaaS.
- Public (shared and low-cost) and private (dedicated and highly controllable), with hybrids combining them.
- Benefits: scalability, no maintenance, access from anywhere, collaborative editing, and backups.
- Risks: simultaneous outages, leaks caused by configuration errors, and lock-in to a particular provider.
Practice Questions
- Explain the difference between cloud computing and on-premises systems.
- Explain the differences among IaaS, PaaS, and SaaS, focusing on how much the provider supplies, and answer which category webmail belongs to.
- Give two benefits of a company migrating from on-premises systems to the cloud and two risks that should be considered.
- Explain why the cloud is suitable for operating an event website whose access increases sharply, using the term “scalability.”
Answers and Explanations
- Answer: Cloud computing is a model in which information resources such as servers and software are not owned by the user but are used as services provided through the Internet. On-premises is the traditional model in which equipment is installed, owned, and operated by the company or individual.
Explanation: The key contrast is “borrowing and using without owning” versus “owning and operating it yourself.” Mentioning pay-as-you-go pricing can earn extra credit. - Answer: IaaS provides infrastructure such as virtual servers, storage, and networks, while the user builds everything above the operating system. PaaS provides the application development and execution environment, including the operating system and databases. SaaS provides the completed software (application) itself. Webmail is SaaS because users use a completed application.
Explanation: As indicated by the initials Infrastructure, Platform, and Software, the categories are distinguished by the layer provided. Writing that lower layers offer more freedom and higher layers are easier to use would also be perfect. - Answer: Examples of benefits: ① Equipment purchase and maintenance are unnecessary, reducing initial costs. ② Performance and capacity can be expanded or reduced immediately as needed. ③ Services can be used from anywhere, and the system is well suited to collaborative editing and remote backups (any two). Examples of risks: ① A provider-side failure can stop services simultaneously. ② Information leaks caused by mistakes in public settings. ③ Dependence on a particular provider (lock-in) can make switching difficult (any two).
Explanation: Check whether two benefits and two risks are described specifically. It is important to balance both sides: the convenience and the risks of entrusting information. - Answer: The cloud has scalability that allows computing resources to be increased or decreased immediately as needed through pay-as-you-go pricing. An event website experiences large fluctuations because access increases sharply immediately after ticket sales begin and then decreases. Therefore, a cloud that can be temporarily expanded for the peak and reduced afterward is more efficient than on-premises systems that must always maintain equipment with peak performance.
Explanation: The answer is correct if it explains the combination of “fluctuating demand” and “the ability to increase or decrease resources immediately.” The key is contrasting this with the waste of keeping peak capacity at all times.