计算机英语(第四版).2.4-作者：刘兆毓、郑家农(普通高等教育“十一五”国家级规划教材).ppt

* PART 1 COMPUTER HARDWARE CHAPTER 2 COMPUTER OPERATING SYSTEM 2-4 THE MIDDLEWARE 2.4 THE MIDDLEWARE Main Point ● What is middleware ● Functions and characteristics of middleware ● Differences between operating system and middleware KEYWORDS: persistent storage 持久储存器 middleware 中间件 Application Program Interface (API) 应用程序接口 variable-length file 可变长文件 relational database 关系型数据库 bundle 捆，卷，捆绑件 host name 主机名 Now that you know what an operating system is, I can turn to the other category of software covered by this book: middleware. [1] Middleware is software is occupying a middle position between application programs and operating systems, as I will explain in this section. Operating systems and middleware have much in common. Both are software used to support other software, such as the application programs you run. 连接词 宾语从句 方式状语从句 同位语 定语从句 Both provide a similar range of services centered around controlled interaction. Like an operating system, middleware may enforce rules designed to keep the computations from interfering with one another. [2] An example is the rule that only one computation may modify a shared data structure at a time. Like an operating system, middleware may bring computations at different times into contact through persistent storage and may support interaction between computations on different computers by 宾语补语 同位语从句 providing network communication services. [3] Operating systems and middleware are not the same, however. They rely upon different underlying providers of lower-level services. An operating system provides the services in its API by making use of the features supported by the hardware. ?1 Which features are the same between operating system and middleware ?