World Wide Web

Spinning the World Wide Web by TONY JOHNSON Tony spins a tale of mystery and intrigue as he takes us on a futuristic journey around the electronic world known as "the Web." F THE IMPORTANCE of developments were to be measured solely in terms of their popular I press coverage, then probably the most significant development to have sprung from the world of high energy physics in the last few years would not be the discovery of the top quark, or even the demise of the SSC, but rather the development of the World Wide Web. This tool (often referred to as WWW or simply as “the Web”) is able not only to access the entire spectrum of information available on the Internet, but also to present it to the user using a single consistent easy-to-use interface. 2 FALL 1994 This has opened up the network, pre- The World Wide Web extends the long as they can be transformed by viously viewed as the home of com- well-established concept of hyper- the server software into the format puter hackers (and crazed scientists), text by making it possible for the des- the client software expects to receive. to a new audience, leading to spec- tination document to be located on This model can naturally be extend- ulation that the Internet could be the a completely different computer from ed to allow documents to be dy- precursor to the much talked about the source document, either one lo- namically created in response to a “Information Super Highway.” cated anywhere on the network. This request from users, for example by The ideas behind the World-Wide was made possible by exploiting the querying a database and translat- Web were formulated at CERN existing capabilities of the Internet, ing the result of the query into a in 1989, leading to a proposal sub- a world-wide network of intercon- hypertext document. mitted in November 1990 by Tim nected computers developed over the From the information consumer’s Berners-Lee and Robert Cailliau for preceding 20 years, to establish a perspective, all the documents on the a “universal hypertext system.” In rapid connection to any named com- Web are presented in the form of hy- the four years since the original pro- puter on the network. pertext. The consumer remains bliss- posal the growth of the World Wide To achieve this, the World Wide fully ignorant of how the documents Web has been phenomenal, expand- Web uses a client-server architecture. are maintained by the information ing well beyond the high energy A user who wants to access infor- provider and, unless he really wants physics community into other acad- mation runs a World Wide Web client to know, from where the documents emic disciplines, into the world of (sometimes referred to as a brows- are being accessed. commerce, and even into people’s er) on his local computer. The client homes. fetches documents from remote net- GROWTH OF THE WEB This article describes the basic work nodes by connecting to a serv- concepts behind the World Wide er on that node and requesting the The initial implementation of the Web, traces its development over the document to be retrieved. A docu- Web client at CERN was for the NeXT past four years with examples of its ment typically can be requested and platform. This earliest browser was use both inside and outside of the fetched in less than a second, even able to display documents using mul- high energy physics community, and when it resides on the other side of tiple fonts and styles and was even goes on to describe some of the ex- the world from the requester. (Or at able to edit documents, but access tensions under development as part least it could be in the early days of was limited to users fortunate of the World Wide Web project. the Web; one of the drawbacks of the enough to have a NeXT box on their enormous success of the Web is that desks. This was followed by devel- sometimes transactions are not as opment of the CERN “linemode” WORLD WIDE WEB CONCEPTS fast now as they were in the earlier, browser, which could run on many The World Wide Web is designed less heavily trafficked days. One platforms but which displayed its around two key concepts: hypertext of the challenges of the Web’s fu- output only on character-based ter- documents and network-based in- ture is to overcome these scaling minals. These early browsers were formation retrieval. Hypertext doc- problems.) followed by the first browsers de- uments are simple documents in The client-server model offers signed for X-Windows, Viola devel- which words or phrases act as links advantages to both the information oped at the University of California, to other documents. Typically hy- provider and the consumer. The Berkeley, and Midas developed at the pertext documents are presented to information provider is able to Stanford Linear Accelerator Center. the user with text that can act as a keep control of the documents he Initially the growth of the World link highlighted in some way, and maintains by keeping them on his Wide Web was relatively slow. By the the user is able to access the linked own computer. Furthermore the end of 1992 there were about 50 documents by clicking with a mouse documents can be maintained by the hypertext transfer protocol (HTTP) on the highlighted areas. information provider in any form, so servers. At about the same time, BEAM LINE 3 10,000 1000 100 FTP for the Internet, and is still the most gy 10 widely used for transferring large 1 files). While the growth in WWW traffic is enormous, it is worth not- –1 Gopher ing that it is still not the dominant protocol; in fact, FTP, e-mail and NNTP (Network News transfer protocol) traffic are all substantially WWW May Jan larger. Sep Owing to the distributed man- May agement of the Internet and the Jan NSFNET Bytes per Month World Wide Web, it is very difficult to obtain hard numbers about the The dramatic increase of World Wide short movie and sound clips; and the size of the Web or the number of Web usage over the past year and a half ability to display forms. Forms great- users. (The number of users on the is illustrated. While the growth rate is ly enhanced the original search Internet, often estimated to be in the phenomenal, more traditional uses of the mechanism built into WWW by al- tens of millions, is itself a con- network such as file transfer and e-mail lowing documents to contain fields tentious issue, with some estimates still dominate. that the user could fill in, or select claiming this number to be an over- Gopher, a somewhat similar infor- from a list of choices, before clicking estimate by perhaps as much as an mation retrieval tool to WWW but on a link to request further infor- order of magnitude.) One illustration based on menus and plain text doc- mation. The introduction of forms of the size of the Web came in early uments rather than hypertext, was to the WWW opened a new arena of 1994 when a server was set up to pro- expanding rapidly with several hun- applications in which the World vide information and up-to-the- dred servers. Wide Web acts not only as a way of minute results from the Winter During 1993 the situation changed viewing static documents, but also Olympics being held in Lillehammer, dramatically, driven in large part by as a way of interacting with the Norway. The implementation of the the development of the Mosaic client information in a simple but flexi- server wasn’t started until the day by a talented and extremely enthu- ble manner, enabling the design of before the Olympics were scheduled siastic group at the National Cen- Web-based graphical interfaces to to start, but two weeks later the serv- ter for Supercomputer Applications databases and similar applications. er (together with a hastily arranged (NCSA) at the University of Illinois During 1993 the usage of WWW mirror server in the United States) in Champaign-Urbana. The Mosaic began to grow exponentially. As new had been accessed 1.3 million times, client for World Wide Web was orig- people discovered the Web they of- by users on somewhere between inally developed for X-Windows un- ten became information providers 20,000 and 30,000 different comput- der Unix, with subsequent versions themselves, and as more information ers in 42 countries. released for both the Macintosh and became available new users were at- NCSA now estimates that more PC platforms. tracted to the Web. The graph on this than a million copies of the Mosaic The Mosaic client software added page shows the growth in World software have been taken from their a few new key features to the World Wide Web (or more accurately HTTP) distribution site, and approximate Wide Web: the ability to display em- traffic over the National Science counts of the number of HTTP bedded images within documents, Foundation backbone since early servers indicates there are more than enabling authors to greatly enhance 1993, in comparison to Gopher and 3000 servers currently operating the aesthetics of their documents; FTP traffic during the same period (Stanford University alone has over the ability to incorporate links to (FTP—file-transfer protocol—was one 40 HTTP servers, not including one simple multimedia items such as of the earliest protocols developed for the Stanford Shopping Center!).

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