Tài liệu (ebook) Working with Active Server Pages pptx

Chapter 1 Understanding Internet/Intranet Development This chapter was written for a special group of people: those who had an unusually good sense of timing and waited until the advent of Active Server Pages (ASP) to get involved with Internet/intranet development. The chapter surveys an important part of the ASP development environment: the packet-switched network. You will learn what this important technology is and how it works inside your office and around the world. The chapter also is a cursory treatment of Internet/intranet technology; details await you in later pages of the book (see the "From Here " section, at the end of this chapter, for specific chapter references). In this chapter you learn about: The hardware of the Internet First, look at the plumbing that enables your software to operate. One important Internet hardware feature affects how you use all of your Internet applications. ● The software of the Internet Learn about the software of the World Wide Web, as well as that of its poor relation, the OfficeWide Web. ● The protocols of the Internet Take a quick look under the hood of the Web (and anticipate a thorough treatment of Internet protocols in later chapters). ● Understanding the Hardware That Makes the Internet Possible The Internet is like one vast computer. It is a collection of individual computers and local area networks (LANs). But it is also a collection of things called routers, and other kinds of switches, as well as all that copper and fiber that connects everything together. Packet-Switched Networks Begin your exploration of this world of hardware by looking at the problem its founding fathers (and mothers) were trying to solve. A Network Born of a Nightmare A great irony of the modern age is that the one thing that threatened the extinction of the human race motivated the development of the one thing that may liberate more people on this planet than any military campaign ever could. The Internet was conceived in the halls of that most salubrious of spaces: the Pentagon. Specifically, the Advanced Research Projects Agency (ARPA) was responsible for the early design of the Net's ARPAnet. ARPA's primary design mission was to make a reliable communications network that would be robust in the event of nuclear attack. In the process of developing this technology, the military forged strong ties with large corporations and universities. As a result, responsibility for the continuing research shifted to the National Science Foundation. Under its aegis, the network became known as the Internet. Internet/intranet You may have noticed that Internet is always capitalized. This is because Internet is the name applied to only one thing-and yet, that thing doesn't really exist. What this means is that there is no one place you go to when you visit the Net; no one owns it, and no one can really control it. (Very Zen, don't you think? At once everything and nothing.) You also may have come across the term intranet and noticed that it is never capitalized. You can probably guess the reason: because intranets, unlike the Internet, are legion; they are all over the place. And every single one of them is owned and controlled by someone. In this book, you will see the term Web used interchangeably for both the World Wide Web and the OfficeWide Web. When this book discusses the Internet, Web refers to the World Wide Web; when it discusses intranets, Web refers to the OfficeWide Web. A Small Target Computers consist of an incredibly large number of electronic switches. Operating systems and computer software really have only one job: turn one or more of those switches on and off at exactly the right moment. The Internet itself is one great computer, one huge collection of switches. This is meant in a deeper way than Scott McNealy of Sun Microsystems intended when he said "The network is the computer." I think Scott was referring to the network as a computer. We are referring, instead, to the switches that make up the Internet, the switches that stitch the computers all together into an inter-network of computers. Scott was emphasizing the whole, we are highlighting the "little wholes" that make up Scott's whole. The reason this is important is fairly obvious. If you take out a single computer or section of the network, you leave the rest unphased. It works. So, on the Internet, every computer basically knows about every other computer. The key to making this work is the presence of something called the Domain Name System (DNS). You will learn details of this innovation in a moment; for now, just be aware that maintaining databases of names and addresses is important, not only for your e-mail address book, but also to the function of the Internet. The DNS is the Internet's cerebral cortex. Working with Active Server Pages - Chapter 1 file:///C|/e-books/asp/library/asp/ch01.htm (1 of 13) [10/2/1999 5:17:07 PM] . the Internet. The DNS is the Internet's cerebral cortex. Working with Active Server Pages - Chapter 1 file:///C|/e-books/asp/library/asp/ch01.htm. unusually good sense of timing and waited until the advent of Active Server Pages (ASP) to get involved with Internet/intranet development. The chapter surveys