9 Apr 1995

World Wide Web Browsers

The recent jump in interest about the Internet has been largely driven by WWW browsers such as Mosaic. The World Wide Web is an informal network of interlinked servers and documents based on standards developed at the European research facility at CERN. It combines a number of old ideas into a system that adds "sizzle" to output, including logos, icons, diagrams, and pictures. Documents can be linked to other documents, and binary files can be referenced and downloaded with the click of a mouse.

A Web browser understands a number of older protocols. It can receive files by FTP, display Gopher menus, and read network news. The "forms" feature can display a fill-in-the-blanks input screen with action buttons. A map image can be displayed, and the user can click on an area of interest. Though most Web requests display files from the server, others can run a program and query a database.

The core of the Web are three new and rather obscurely named standards:

  1. HTTP (Hypertext Transfer Protocol) a new client/server protocol similar to Gopher. In its simplest form, the client sends the name of a document or file and the server sends the document back. Unlike Gopher, there is no formal "menu" structure. Instead, documents can contain embedded pointers to other documents.
  2. URL (Uniform Resource Locator) a super-general designation for a document, file, menu, directory, or service anywhere on the network. A URL has four parts: a type of server protocol (Gopher, FTP, HTTP) followed by a colon, a server computer name preceded by two slashes (i.e. //pclt.cis.yale.edu), the name of a thing (a file, directory, newsgroup, menu, selector, or program), and a "last piece". The last piece of a document might be a bookmark (a named location in the middle of the document to use as the starting point). When the thing is a program, the last piece is a parameter string to pass to the program.
  3. HTML (HyperText Markup Language) a language for embedding format information in plain text files. A line can be marked as a section title, so the browser will display it in larger characters. Strings can be marked to display in italics or bold. HTML can include references to other files on the same server or on other servers. It can also reference images to be displayed in with the text. Web documents are not formatted by the server. The server sends HTML, and the Browser program on the client decides what font to use, how wide to make each line of text, and how to add emphasis.

To the extent that "The Web" has any specific meaning, it generally consists of servers that process HTTP transactions where the remote client sends the trailing end of a URL as a query and respond with a text file in HTML format. The pclt.cis.yale.edu server performs this function. This document, and the rest of the PCLT library, consist of Word files that have been converted to HTML format for display. Embedded icons, buttons, and diagrams are stored on the server as GIF-format image files referenced at the point where they are to be inserted in the HTML document.

As Web Browsers have evolved, they improve over the original Mosaic program's limited ability to deal with other protocols. Netscape is a fairly good Network News reader. A modern browser should automatically load binary files to disk, instead of trying to display them on the screen. Still, WSGOPHER understands GOPHER+ preferences, specialized Mail packages have nicknames and log files, and WS_FTP and NetSuite FTP for OS/2 display more directory information than any Web Browser. It is premature to expect that a Web Browser will replace all the other programs.

Web Browsers can display plain text files, HTTP, GIF or XBM images, Gopher menus, and FTP directory listings. Other types of data (PostScript documents, JPEG images, AU sound) may require an external viewer program. Some Web Browsers may have extra viewers built in, some may ship with selected viewers, and some may require that the viewer program be installed separately and configured.


Given the tremendous interest in Internet and the Web, a number of browser programs have been recently released. Each program had serious bugs and important limitations. Many were fairly slow. There was no clear leader.

Then literally overnight things changed. On Oct 14 Mosaic Communications Corporation, a company formed by some of the original authors of NCSA Mosaic, released Netscape Version 0.9. Although nominally a "Beta Test" release, this code is much more reliable than any of the other programs. It is fast, especially for users connected to the Internet over a phone line. It is trivial to install and runs on all systems. Instantly, it became the front-runner. Best of all, it is absolutely free for personal use!

When a Web Server transfers a document to a browser, it first sends the HTML text. In HTML, the elements of the document are marked but their format is not specified. In this example, the phrase "How to Create WWW Services" will have been marked as a headline by the server. The Browser decided just how large to make the characters to set this headline apart from the ordinary text. The browser also formats the following paragraph to flow within the width of the window. The HTML file will contain the name of another file containing the GIF image of the picture that appears at the top. Traditional first-generation browsers, such as NCSA Mosaic, would first read in the entire HTML document, then format it, then fetch the picture, and finally display everything together. This worked adequately on Unix systems connected by LAN to a high speed network.

Netscape is optimized for a 14400 baud modem. The authors have reorganized the original Mosaic code so that it formats the text as it is read in. Since the phone line is fairly slow, this effectively uses the spare CPU power available during the data transfer and allows the data to be displayed almost instantly after the modem transfer ends. When the reference and name of the GIF picture file is encountered, Netscape generates a separate query the server requesting information about the picture data. Once Netscape determines the size of the picture, it can leave an empty box as a placeholder where the picture will appear, and go on formatting the text. After all the text has been transfer, Netscape goes back to fetch the pictures and fills in the empty boxes.

Windows applications are "event driven." This means that the application program runs when it is told by Windows that the user has moved the mouse, pressed a button, or hit a key on the keyboard that is directed to that program. In response to such events, the program may change things on the screen, or read and write files on disk. The WINSOCK interface was designed so that network operations could be handled as a single operation (like a disk request) or they could run in the background and complete by putting an event on the same queue that handles mouse clicks.

Good programs will use the event programming model, but very few programs are well written. Netscape performs all of its network activity using the event model. This means that the mouse pointer never becomes an hourglass, and the user is always free to click on a button, follow an interesting link, pull down a menu, or cancel an operation. The current screen does not have to be fully painted before the user goes on to another document.

Although all WINSOCK packages are supposed to support this type of activity, it is unusual to find well written programs. So this type of concurrent activity may not have been thoroughly tested with your existing WINSOCK package. Current Beta versions of Trumpet WINSOCK 1.0B work. The IBM WINSOCK package for OS/2 works. If Netscape does not work on your system, then you might try a different browser. Or you might get a better WINSOCK.

Netscape has an astonishingly good news reader, for a program that doesn't advertise itself as a network news package. It is realatively unsophisticated about "bookmarks" (saving the references to interesting places in the Web so that you can reload those documents later on). There are a few bugs to fix, but nothing of great importance.

The current version of Netscape cannot print documents. This is, after all, the 0.9 Beta release of the package and printing is an understood requirement for the next release.

Mosaic Communications Corporation appears to be targeting to electronic publishing. Their product extends standard HTML to provide additional formatting options needed to adequately display more complex content. Perhaps this gives PCLT a bias to Netscape, since its design exactly matches the objectives of PC Lube and Tune.

Air Mosaic from Spry

Air Mosaic is another commercial derivative of the original NCSA code. It is available from Spry, the company that also gives you Internet in a Box. Every other Web Browser is at some level of "beta test." Spry was the first company to claim a "product" level version, and after a month they cleaned up most of the bugs. In its basic functions, it acts like every other Web Browser. It has two special features. First, its handling of tables of interesting Web locations is unusually go. The "hotlists" are organized in a hierarchy much like the file structure of the computer.

This is much easier to use than the simple lists of recently viewed pages maintained by the other Web browsers. Spry is also remarkable in the way it is distributed. You download a free test version that can display local files, files on the Spry server, and a handful of other documents from other servers on the Web. Of course, you can stop and restart the program and view another handful of files. After verifying the speed and accuracy of the program, the user can upgrade from test to product version over the network. Spry displays a fill-in form for the name, address, and credit card number. This information is encrypted, so that the card number cannot be intercepted by anyone on the network. When the transaction is complete, the test version is converted to a fully functional Web browser with no limitations. The price of $30 for this program would be quite reasonable, if it were not for the fact that Netscape is free.

Spry has a lead in developing commercial uses of Web technology and the Internet. They were featured in a recent announcement by GE that it would use the Web to communicate with customers and suppliers. Spry seems to be more interested in the Home Shopping Network view, where the Web is used to advertise, catalog, and order other items. Netscape is targeted to the Electronic Publishing side of the Web, where the information distributed is itself the marketable commodity.

There are supposed to be 16-bit and 32-bit versions of the code. It is fairly fast, but the main reason for interest is that it provides a commercial view of Web use and is designed and marketed more aggressively to the consumer marketplace. The other Web Browsers are targeted more to sophisticated computer users and researchers.

NCSA Mosaic

NCSA continues to release its own version of the original Mosaic programs. Their code creates a new standard in "leading edge" programs. It appears that the next release is written four months in the future, and then through some secret process is transmitted back in time before Microsoft releases the systems, libraries, and support routines needed to run it.

NCSA approaches the Web with brute force. To achieve the fastest possible execution (and perhaps to maintain compatibility with the Macintosh, PowerMac, and Unix versions of the code) Mosaic has migrated everything to 32-bit programming. The WIN32 interface is native to Windows NT, and it will be a standard feature of Windows 95 (Chicago). Today, however, running 32-bit code in Plain Old Windows 3.x requires a package called WIN32S.

WIN32S is not exactly intended as a direct Microsoft package. Rather, it gets bundled in with some other product designed to use it and is installed as needed. Unfortunately, the installation process does not always run cleanly, and interactions between this code and other optional features and libraries are often a problem.

It was worth the effort to struggle with Mosaic when there were no better alternatives. Now that Netscape and Air Mosaic are out, it makes no sense to run NCSA Mosaic on machines with Plain Old Windows. If you are running Windows NT 3.5 Workstation, particularly on a MIPS or Alpha RISC system, or if you are running one of the Beta releases of Windows 95, then it may be worth trying it out.

OS/2 Web Explorer

During 1994, Web Explorer will be distributed electronically through the Internet to customers who have purchased the Warp OS/2 operating system. When all features of this program have been developed, it will be added to the OS/2 package.

The current 0.91 Beta Test version shows much promise. It is already a remarkably stable and functional entry. Since OS/2 is natively a 32-bit environment, it can match the raw performance of NCSA Mosaic. When product development is completed, it will add multi-threading capability and may match the sophistication of Netscape.

Web Explorer has and advantage over other network tools because it is an integral part of the overall operating system package. It is well know that Warp comes with integrated Internet support. It is less obvious that it also includes a number of multimedia components previously sold separately under the "Ultimedia" label. If the user has a sound card, special display hardware, or a DSP chip, then Warp has an integrated structure and tools to tie it all together. Web Explorer has the ability to internally process most image formats, and it comes preconfigured with links to other Warp utilities to play sound and display several motion video formats.

The Windows user has to accumulate a comparable set of tools from shareware libraries. Some of these programs don't work well, most are fairly slow, and two shareware registrations can end up costing more than the street price of Warp. Although it is theoretically possible for an ordinary user to configure all the Windows Internet navigation tools with a working set of viewer programs, Warp makes the process immediate and automatic.

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Copyright 1995 PC Lube and Tune -- Windows on the World -- H. Gilbert