Personal Computing, Distributed Computing and Client/Server Computing

Personal Computing, Distributed Computing and Client Server Computing

In the early years of computing, computer systems were too large and too expensive for individuals to own. In the 1970s, silicon chip technology appeared, making it possible for computers to be much smaller and so economical that individuals and small organizations could own the machines. In 1977, Apple Computercreator of today's popular Macintosh personal computers and iPod digital music playerspopularized personal computing. In 1981, IBM, the world's largest computer vendor, introduced the IBM Personal Computer, legitimizing personal computing in business, industry and government organizations.

These computers were "stand-alone" unitspeople transported disks back and forth between computers to share information (creating what was often called "sneakernet"). Although early personal computers were not powerful enough to timeshare several users, these machines could be linked together in computer networks, sometimes over telephone lines and sometimes in local area networks (LANs) within an organization. This led to the phenomenon of distributed computing, in which an organization's computing, instead of being performed only at some central computer installation, is distributed over networks to the geographically dispersed sites where the organization's work is performed. Personal computers were powerful enough to handle the computing requirements of individual users as well as the basic communications tasks of passing information between computers electronically.

Today's personal computers are as powerful as the million-dollar machines of just a few decades ago; complete personal computer systems often sell for as little as $5001000. The most powerful desktop machines provide individual users with enormous capabilities. Information is shared easily across computer networks, where computers called file servers offer a common data store that may be used by client computers distributed throughout the networkhence the term client/server computing. In Chapters 1922, you'll learn how to build Internet- and Web-based applications; we'll talk about Web servers (computers that distribute content over the Web) and Web clients (computers that request and receive the content offered up by Web servers).