Learning Perl on Win32 Systems

Appendix C. Networking Clients

Few computers (or computer users, for that matter) are content to remain isolated from the rest of the world. Networking, once mostly limited to government research labs and computer science departments at major universities, is now available to virtually everyone, even home computer users with a modem and dial-up SLIP or PPP service. More than ever, networking is now used daily by organizations and individuals from every walk of life. They use networking to exchange email, schedule meetings, manage distributed databases, access company information, grab weather reports, pull down today’s news, chat with someone in a different hemisphere, or advertise their company on the Web.

These diverse applications all share one thing in common: they use TCP networking, the fundamental protocol that links the Net together.^[113] And we don’t just mean the Internet, either. Firewalls aside, the underlying technology is the same whether you’re connecting far across the Internet, between your corporate offices, or from your kitchen down to your basement. As a result, you only have to learn one technology for all sorts of application areas.

How can you use networking to let an application on one machine talk to a different application, possibly on a totally different machine? With Perl, it’s pretty easy, but first you should probably know a little bit about how the TCP networking model works.

Even if you’ve never touched a computer network before in your whole life, ...