聊城大学计算机学院计算机操作系统（1）英文课件 Chapter14.ppt

Distributed Processing, Client/Server, and Clusters Chapter 13 Client/Server Computing Client machines are generally single-user PCs or workstations that provide a highly user-friendly interface to the end user Each server provides a set of shared services to the clients The server enables many clients to share access to the same database and enables the use of a high-performance computer system to manage the database Client/Server Terminology Applications Programming Interface (API) A set of function and call programs that allow clients and servers to intercommunicate Client A networked information requester, usually a PC or workstation, that can query database and/or other information from a server Middleware A set of drivers, APIs, or other software that improves connectivity between a client application and a server Relational Database A database in which information access is limited to the selection of rows that satisfy all search criteria Server A computer, usually a high-powered workstation, a minicomputer, or a mainframe, that houses information for manipulation by networked clients Structured Query Language (SQL) A language developed by IBM and standardized by ANSI for addressing, creating, updating, or querying relational databases Client/Server Applications Basic software is an operating system running on the hardware platform Platforms and the operating systems of client and server may differ These lower-level differences are irrelevant as long as a client and server share the same communications protocols and support the same applications Client/Server Applications Bulk of applications software executes on the server Application logic is located at the client Presentation services in the client Database Applications The server is a database server Interaction between client and server is in the form of transactions the client makes a database request and receives a database response Server is responsible for maintaining the database Client/Server Datab