第6章インフラストラクチャーの抽象化層：オペレーティングシステム

Virtual machines have an impact on every industry today as they facilitate the running of numerous business applications. For example, most companies use Google Mail or Microsoft Outlook to supply their employees with email services. These are Software as a Service (SaaS) cloud infrastructures that operate the email software by making use of virtual machines that run in Google and Microsoft Cloud data centers.

A major advantage of SaaS email might be portability. Because the application can run on any local machine with an appropriate browser, this enables users to use the app on many different platforms, including mobile phones and tablets. In addition, there is an automatic backup of saved data, and no need for complicated installations and configuration. The disadvantages of SaaS might include the lack of security of the data stored in the app with respect to unauthorized access and the inability of users to use the application when the network connection is weak or nonexistent.