Karl Jeacle
September 1994
Just Amiga Monthly Issue 48
Sometime early last year when setting up our company Internet connection, I heard great things about an Internet tool called Mosaic, and was anxious to try it out. However, when I did get around to trying it I found it connecting to some site in the USA, and unfortunately, over our low-speed Internet link, whatever it was doing, it was just unbearably slow.
Six months later, I decided to try again. I got a copy of the latest version and started over. This time was different. The interface had been completely revamped. From some sort of tool which tried to integrate every Internet tool into one, this version seemed much more focussed. Still unsure exactly what I was doing I chose the `Open URL' menu option and typed in a `URL' I had found in someone's signature. Seconds later, a rather neat mix of text and graphics filled my screen. I had found the `home page' of a local computer company. Revelation!
Mosaic is just one of many browser programs for the World Wide Web (also referred to as WWW or W3). It's hard to describe the Web without actually demonstrating it by running Mosaic, but hopefully this article will give you a reasonable idea of what all the fuss is about.
Formally, the Web can be described as a hypermedia document system i.e. a hypertext system which supports links not just to text but to other media types such as still images, video and audio. Furthermore, the Web is distributed. Unlike conventional hypertext systems where links point to local documents, Web documents can contain links which point to objects residing on remote machines.
Try imagining an enhanced version of AmigaGuide: make the text a little richer using a variety of different sized fonts; next embed images within the document text. Finally, network a few Amigas together on the Internet, each with their own AmigaGuide files. Place a few special links in these files which make them point to the AmigaGuide files on the other networked machines.
Now by using your new AmigaGuide browser on one machine, you can click on what looks like just another link, and transparently view a page stored on a different machine. And by clicking on a link contained in that page, you retrieve a page from yet another machine. Link enough of these together, and eventually you'll give rise to a web effect all over the world. A World Wide Web.
WWW was originally conceived by Dr. Tim Berners-Lee in 1989 as a means of sharing information between high energy physicists working at CERN in Geneva. Since then, it has spread to millions of users throughout the world, due in no short way to the Mosaic program.
Mosaic was created by the NCSA (National Center for Supercomputing Applications) Software Development Group at the University of Illinois. Over the last couple of years, they have created versions of Mosaic for the X Window System, Windows, and the Macintosh.
Mosaic for the Amiga, on the other hand, has no formal link with NCSA, although AMosaic is based on NCSA Mosaic. It has been developed by a group of Amiga users on the Internet: Michael Fischer, Michael Witbrock, Michael Meyer and Steve Dunham.
Of course, Mosaic isn't the only browser available for the Web. A number of others such as Lynx, Cello and ViolaWWW exists on a variety of platforms, but Mosaic is probably the most polished and definately the most widely used.
People tend to refer to Mosaic and WWW as though they are the same thing, but this is not the case. Web browsers are completely independent of the data. The WWW as developed by CERN can be thought of as just a way of structuring data. NCSA Mosaic is one of many browsers which can read that data, interpret it, and display it on screen.
In the same way Commodore developed AmigaGuide, CERN created WWW. If you don't like Multiview (or Mosaic), you can write your own browser.
The language used to write a page of Web data is called HTML --- the HyperText Markup Language. It is essentially a collection of styles used to define the various components of a W3 document. In use, it's quite similar to TeX or LaTeX. Here's a small example:
<HTML> <HEAD><TITLE>This is the title of my document</TITLE></HEAD> <BODY> <H1>This is a level one heading</H1> Here is some normal text. We can have <B>bold</B> text or words in <I>italics</I>. We can put paragraphs at the end of our text.<P> We can include a GIF picture right here: <IMG SRC="amiga.gif"> We can even make links to other web pages by doing <A HREF="index.html">this</A>. </BODY> </HTML>
In order to network all these HTML files on different machines, a protocol is needed to transfer data between the client browser and Web server. Enter HTTP --- The HyperText Transfer Protocol.
HTTP is transport protocol independent, which means it can be implemented using any underlying transport protocol, such as TCP/IP or Novell IPX. However, almost all current implementations run over TCP, usually on port 80. Hence the requirement for AmiTCP or CBM AS225 software if you want to start net-surfing with Mosaic.
Setting up a Web server is as simple as running a program called HTTPD which is a `daemon' program that just sits listening on TCP port 80 waiting for incoming requests. These requests can be as simple as "GET /" which would request the server's root or home page. As a user, you don't need to know anything about HTTP itself. Your browser sends the commands to the HTTPD server for you.
One of the innovations which has come with the Web is the URL --- the Uniform Resource Locator. The URL, as the name implies, is a uniform way of specifying how resources on the Internet can be located. For example:
NCSA's W3 Server
The Amiga WWW home page
http://www.cs.cmu.edu:8001/Web/People/mjw/Computer/Amiga/MainPage.html
The location of Amiga Mosaic
ftp://max.physics.sunysb.edu/pub/amosaic/Mosaic_1.2_AmiTCP.lha
A WWW browser accessable via telnet
My home page on the Web!
The 8001 in the Amiga WWW home page URL means that browsers should open a connection to the TCP port 8001 on www.cs.cmu.edu instead of 80, the default HTTP port.
In July 1994, Web traffic was ranked number 4 on the American NSFNET backbone, with over 1000 terrabytes of web data transferred during the month. And if you think that's a lot of data, think again --- it only accounted for 6.5% of the total July NSFNET backbone traffic...
No one knows for sure just how many WWW servers there are out there, but CERN maintain a list of `registered' Web servers. When people set up a new server, CERN encourage them to register so they can keep some sort of handle on the amount of servers out there. At the time of writing, there were almost 2500 servers listed worldwide. In reality, the real number of servers is probably almost double this, as many people either don't register with CERN or have multiple servers hanging off one link on CERN's page.
In July 1994, CERN and MIT announced the W3 Organization, an initiative to further development and standardization of the Web.
Dr. Martin Bangeman, the Commisioner of the European Union in charge of industrial policy, information technologies and telecommunications commented 'The European Union intends to support this cooperative activity as an important step toward the Global Information Society'.
It seems the Web has come a long way from the early days in the research labs and universities. Today, Mosaic is the most exciting tool available for exploring the Internet. If you're looking for an on-ramp to the much hyped Information Super-Highway, then look no further.
www1.gif - AMosaic browser for the Amiga
www2.gif - Home page of Amiga WWW site
www3.gif - Sensitive map of Irish Web sites (for CUGI)
Just click on the names shown to connect to the Web servers
www4.gif - Sensitive map of UK+I Web sites (for JAM)
Just click on the dots shown to find Web servers available
News, weather and statistics are also available.
