Argo is a 2nd-generation World-Wide Web browser. It will give
its user access to most of the resources available on the
Internet, through its easy to use hypertext/multimedia
interface. It will also help the user to organize the
information and to react to it.
Note: Argo is still under development. The project
officially started in August '94. The program that is shown
doesn't have all the features the final version will have.
Version~1.0 should be ready around October 1994.
In comparison to the current crop of WWW browsers, such as Mosaic, Cello, WinWeb and Lynx, it is much more extensible and customizable. There are other innovative features as well. Here is a list of the main ones:
Argo is designed specifically for, and in cooperation with, scholars in the Humanities. Within the Faculty of Arts in Groningen, where it is being developed, a diverse group of people periodically provides feedback on the project.
Argo makes use of `plug-in' modules. New functions can be added without recompilation, thanks to a special interface called W3A (WWW Applets).
`Applets', as the modules are called, can add support for new data formats, new protocols, and special functions, such as bookmarks, graphical navigation, e-mail editors, and remote-control. Of course, it is also possible to take out an existing applet and insert a better one in its place.
Argo supports multimedia synchronization. Although there aren't many multimedia documents available on the Web today (apart from HTML with in-lined images), standards such as HyTime promise to change that shortly. Within the WWW community people have been looking for a so called `client-side script language' for some time now. ISO is also working on it.
The method Argo uses is message broadcasting. An `event' occurring in a viewer, no matter how deeply nested within other viewers, is broadcast by Argo to all active viewers. This can be used to pass mouse clicks on a `clickable image' to the parent HTML viewer, or to provide timing signals for two animations that must be run in parallel.
Here are some of the functions that are expected to be in one of the early releases of Argo. Some are required by current practice, others are requested by the users panel.
Support for the common protocols: HTTP, Gopher, FTP, WAIS, NNTP. Note that all of these are provided as `plug in' applets; the Argo kernel doesn't know any of these protocols.
Support for the common data formats: HTML (2.0 and 3.0), GIF, JPEG, XBM, XPM, plain text; again as applets.
Proxy (or cache) support.
E-mail and news reading and sending.
Hotlists and history.
On-line help in Dutch as well as English.
The first round of consultation with the users led to many more wishes, that, for various reasons, can't be fullfilled immediately. Those wishes include: an interface to various library catalogues with the possibility to save the result for use in bibliographies, a viewer for TEI documents, import and export of various dataformats, a one-day course, and usability over a modem. Coordination with other projects may solve some of these issues.
In W3A, applets are classified as either agents, viewers, filters, printer drivers or user functions (a.k.a. `accessories').
Agents are responsible for retrieving documents over the network. There are HTTP agents, Gopher agents, FTP agents, etc.
Viewers display a document in a certain format. Examples are viewers for GIF, HTML, audio, plain text, MPEG. Because of W3A, all viewers display their output through Argo, which means that the user notices no difference.
Filters convert documents from one format to another. For example, when there is a good viewer applet available for GIF, but not for TIFF, one could install a TIFF to GIF converter. Other useful filters are, e.g., plain text to HTML, and HTML to Postscript.
Printer drivers are like viewers, except that they output to a printer and not to the screen. There should be printer drivers for most of the formats for which there are viewers, except that some formats (sound, movies) are not printable.
User functions (`accessories') provide special functions, such as a history list, a hotlist, a note pad, a remote control utility, a graphical map of (a fragment of) the Web, or more frivolous things, such as a puzzle or a quote of the day.
The success of the W3A approach depends on wide enough acceptance. It is designed with the dual goal of being easy to implement and easy to install by end-users. When there is a large choice of applets available, everybody can customize his browser to his liking. W3A should also make it feasible to experiment with new protocols or data formats, since it won't be necessary to modify the browser.
To give an indication of the size of an applet: agents for HTTP, Gopher or FTP can be written in about 150--250 lines. A viewer for GIF (X Windows) takes about 500 lines, of which 4/5 is GIF decoding and 1/5 is for W3A and window management. A plain text viewer is about the simplest viewer possible: it takes less than 75 lines. A viewer for HTML is much larger, of course, more than 4000 lines.
Argo is part of the PROSA project. It is being developed by:
Bert Bos
Department of Humanities Computing, University of Groningen
PO box 716
NL-9700 AS GRONINGEN
E-mail: bert@let.rug.nl
with support from the NBBI. As yet, no policy has been agreed
upon for licensing the program. For information, please contact:
NBBI, attn. Anouk Kramp & Leo Pennings
PO Box 90544
NL-2508 GM DEN HAAG
E-mail: nbbi@inter.nl.net