March 1994 - Volume 10:5
By Daniel Updegrove and Judy Smith
Last year, anyone interested in browsing the Internet was directed to Gopher, software that integrates campus-wide information systems, such as PennInfo, and many other resources around the world, including:
This year, the networking community is buzzing about Mosaic, a snazzy Internet browser for Macintosh, Windows, and X-terminals, which subsumes Gopher and adds new functions:
World-Wide WebMosaic is eye-catching because of its slick, multimedia interface; it is important because it is the first widely used vehicle for presen- tation of networked hypermedia. A system for non-linear linking of information was first conceived by Vannevar Bush in his seminal 1945 article, "As We May Think." Several years ago the Center for Nuclear Energy Research (CERN) in Geneva applied this concept, that anything might be linked to anything else, on a grand scale--the Internet--and created World-Wide Web (WWW). WWW was widely admired for its design, but it lacked both an attractive interface and a substantial body of appropriately coded information to demonstrate the usefulness of hypermedia. Then, last fall, the National Center for Supercomputing Applications (NCSA) at the University of Illinois released Mosaic, a free desktop software interface for WWW with remarkable power and ease of use.
But what's available in the World-Wide Web that's not in Gopher? A great deal, much of it information that has been added recently, in numerous academic disciplines and commercial spheres. A critical difference between WWW and Gopher is that hypermedia information has to be specially coded (using HTML, the HyperText Markup Language) to designate formatting as well as which document components constitute "links," and what happens (retrieve another document, play audio or video, launch Gopher) when a link is highlighted via a mouse click. Such coding was too much effort for most potential information providers until Mosaic became popular--and Mosaic becomes more popular as more hypermedia information is added to the Web.
Home pagesMost information systems present users with a "main menu," a content-free list of alternative functions, resources, or other menus. After selecting from several menus, the user is rewarded with financial data, bibliographic citations, a document or graphic, etc. Hypermedia systems are different: They typically start with introductory text and graphics, some of which are underlined or color-coded to signify that they provide links to something unseen (and perhaps resident on a computer 10,000 miles away). Such starting points are called "home pages."
Mosaic normally comes pre-loaded with an NCSA home page as well as an "NCSA What's New Page" that is updated daily. NCSA's "What's New," in turn, contains hypermedia links to home pages being created all over the Internet by research projects, academic departments, government agencies, corporations, and individuals. In fact, having one's own home page is the latest status symbol in some technical circles.
Exploring Penn's corner of the WebUsers who obtain Mosaic software from Penn's FTP server (see sidebar) will find that Penn's home page (shown on page 12), launches on startup (there are menu selections under the Navigate menu that retrieve important NCSA pages). Penn's home page contains links to other Penn World-Wide Web servers; PennInfo, Gopher, and PennExpertise; the ASCII and PostScript versions of the PennNet PassPort (a guide to networking at Penn); SEPTA rail schedules; and a variety of other information services at Penn and around the Internet. Textual links to these resources are displayed as underlined text. Penn's home page includes a few graphical components, but the automatic display of these graphics can be "turned off." If graphics are turned off, they appear as icons which, like textual links, require activation via a mouse click. Users browsing WWW via dial-up connections (using Serial Line IP) must either turn graphics off or suffer through interminable red lights on the information superhighway.
Several of the links available from Penn's home page illustrate the dedication of individuals and groups to provide--in keeping with long cherished Internet traditions--high-quality, free information resources. At Penn, the flowering of this tradition is apparent in the many home pages created by students. For instance, Marty McCormick, a student in the College of Arts and Sciences), maintains "The Curtis Organ" page, which contains a full color picture of the famous organ, a history lesson, and a few sound clips. One of the most creative efforts to share topical information came during the Winter Olympics. A joint effort of Sun Microsystems, Skrivervik Data, NBT, and Oslonett led to the hourly posting of game results on a WWW server and to a large archive of poignant graphics.
Penn's home page, like many others in WWW, is quite large and must be "scrolled" down using the familiar windowing slider bar scrolling feature. Viewing linked objects is accomplished via a single mouse click. For example, clicking on the underlined text "PennInfo" launches the campus-wide information system. (The main menu looks a bit different than "usual" since almost all the text on the menu consists of underlined hypertext links.) The left pointing arrow at the top of the Mosaic window allows navigation backwards--through documents or objects previously visited in WWW. The globe at the top of the screen indicates when WWW is executing a link and can also be clicked on to stop an activity that seems to be taking too long.
Hotlists and URL'sMost WWW explorers soon find resources that they wish to visit often--for instance, the Library of Congress, a favorite database or two, a subject-oriented Internet guide, or a favorite Web search utility. But they may not remember the exact series of selections that got them to these resources in the first place. To help users navigate quickly through the thousands of resources offered in WWW, Mosaic provides a "hotlist" feature that lets them easily create their own links. To create a link, all that needs to be done is to navigate to the resource of interest and then add it via a pull-down menu.
Alternately, resources can be added directly to the hotlist using a URL. A URL (uniform resource location) is an extended address that contains the information that Mosaic needs to establish a link to a specific resource in World-Wide Web. For instance, the University of Geneva's W3 Catalog search utility (similar to the Veronica search utility in the Internet Gopher) has the URL http://cui_www.unige.ch/w3catalog. This address can be typed directly into the hotlist and then used to launch the search utility.
Network navigators who develop personal sets of resource-specific URL's can get to points of interest in the Web quickly and easily. URL's can be culled during exploration of system (they are noted at the top of the screen as the pointer moves across links on the page); by word of mouth from colleagues; from articles in the popular press; or by using a WWW search tool like the W3 Catalog. Of course, in our corner of the world, one of the most important is http://www.upenn.edu. Come visit.
Traffic jams on the information superhighway?Does Mosaic make it too easy for non-technical users to locate and retrieve illuminated manuscripts and Bach fugues? (Some say that's what the Internet is for!) Will "serious" work be delayed in networks congested by WWW explorers viewing documents festooned with gratuitous graphics? Moreover, will PennNet and the Internet have the capacity to support exponential growth in the number of users with high-powered workstations requesting large, multimedia objects--from distant servers --and expecting instantaneous response?
All universities and information-intensive organizations are grappling with such questions, because Mosaic is only one driving force behind the Internet's remarkable evolution from a technical research environment to an information superhighway. Demands for distributed computer workstation sharing and database access for scientific collaboration, as well as video and audio teleconferencing for distance education are also straining the current infrastructure.
Fortunately relief is on the horizon. At the national level, a higher-capacity backbone has just been funded by the National Science Foundation. PREPnet, Pennsylvania's component of the Internet, is quadrupling the bandwidth of its gateway to the national backbone. In parallel, PennNet capacity and reliability are being upgraded, from office wiring to electronics closets to Penn's interface to PREPnet, and a PennNet Architecture Committee has been formed to scope future needs. Given the dynamism of the Internet, one of the Committee's most difficult tasks will be to forecast "next year's Mosaic."
DANIEL UPDEGROVE is Associate Vice Provost for Information Systems and Computing, and Executive Director of Data Communications and Computing Services. JUDY SMITH is a Technical Writer for ISC Communications Group.
Sidebar 1: References
"A free and simple computer link, by John Markoff, The New York Times, Wednesday, December 8, 1993, Late Edition.
"As We May Think" by Vannevar Bush, Atlantic Monthly, 176/1, July 1945, pp. 101-108.
"Navigating the Internet: Tools for discovery" by Daniel Updegrove and Judy Smith, Penn Printout, Volume 9, Number 4, February 1993, p. 1
Sidebar 2: Mosaic toolbox
Mosaic requires an IP/Ethernet (or SLIP) connected workstation and TCP/IP software such as MacTCP or LAN WorkPlace for DOS. The Mac and MS-Windows Mosaic browsers are available via anonymous FTP (ftp.upenn.edu) in the directories pub/mac/Mosaic or pub/pc/mosaic. External view-ing software, which allows you to view hypermedia objects in WWW are also available. For information about SLIP, check PennInfo (keyword "slip").
In addition to an IP/Ethernet (or SLIP) network connection, the Macintosh Mosaic browser requires System 7 or later, 4 Mbytes of RAM, a hard disk, and MacMacTCP 2.0.4. In addition, you'll want to obtain external viewers such as JPEGView (displays GIF/JPEG images), GIFConverter (displays TIFF images), Simple Player (displays Quicktime movies), Sparkle (displays MPEG movies), SoundMachine (plays audio files), and Stuffit Expander.
If you have an IP/Ethernet connected Mac, you are probably running MacTCP 1.1.1. To upgrade to 2.0.4 you can FTP to ftp.upenn.edu, and get the file mactcp-2.0.4.sit located in the site/mac/mactcp directory. (Note: You must log in to the FTP server using your PennNet ID and password when accessing the "site" directory.) If you do not have MacTCP on your Ethernet-connected computer, you can obtain the latest version from the CRC at 38th and Locust Walk. Please bring a blank diskette.
In addition to an IP/Ethernet (or SLIP) network connection, the Windows PC Mosaic browser requires an absolute minimum of a 80386SX- based machine with 4 Mbyte RAM (a 33 MHz or faster 80486 with at least 8 Mbyte of RAM is recommended); Microsoft Windows 3.1 running in enhanced mode; and a version of TCP/IP that is Winsock 1.1 compliant (such as that offered with LAN WorkPlace for DOS v4.1). External viewers such as Lview (displays GIF/JPEG images), MPEGPlay (displays MPEG movies), Wham (plays audio) and GhostScript (displays PostScript files) are also available.
For more information about obtaining LAN WorkPlace for DOS please contact the DCCS help desk, 898-8171, or help@dccs.