Re: Universal network graphics language

wei@xcf.Berkeley.EDU (Pei Y. Wei)
Date: Fri, 28 Jan 94 08:02:44 -0800
From: wei@xcf.Berkeley.EDU (Pei Y. Wei)
Message-id: <9401281602.AA21358@xcf.Berkeley.EDU>
Subject: Re: Universal network graphics language
Content-Length: 3391

In some ways, I think the ViolaWWW browser is developing some 
capabilities that could possibly be useful for the ideas being 
discussed here, particuarily relevant along the lines of "objects" 
and "scripts".

Right now, the ViolaWWW that is under development can embed viola 
objects/applications inside of HTML documents. This is useful in that,
for example, if you needed a hyper-active tree widget in your HTML 
document, and HTML+ doesn't happen to define it, you could build it as
a mini viola application. Same thing with customized input-forms that 
could conceivably do complicated client-side checking. Or, complex 
tables. Or, a chess board.

You'd basically have a simple GUI toolkit and language at your disposal,
along with HTML.

To make this a bit more concrete, here's an simple example of one
viola object being embedded into a HTML doc.

<P>Watch Big Bird count from zero to infinity: 
<LINK REL="vobj" HREF="">.

Listed below is what the file "" would look 
like, just to give people a feel of the language:

\class {txtLabel}
\name {count}
\script {
        /* This object counts and displays 
        switch (arg[0]) {
        case "setup":
                /* arg[1] == parent object
                 * Convention sez to link to the parent object (the 
                 * document object).
                set("parent", arg[1]);
                after(50000, self(), "tic"); /* start counting in ~5 secs */
        case "tic":
                /* Increment and display. Call self after 10000 micro secs.
                set("label", n++);
                after(10000, self(), "tic");
\font {normal_large}
\width {200}
\height {50}
\BGColor {darkGreen}
\FGColor {white}
\BDColor {black}

To implement the chess board interface, you'd *basically* write a 
mini viola application that consists of: objects for representing 
board-cells, chess pieces; an object doing the talking with the chess 
server; a clock object; text fields for IRC type communications...

The ViolaWWW browser could fetch this chess-board-application 
(embedded in HTML or not) from a WWW server, and renders it on the fly.

Now, what I've just described is, I think, more of GUI than Graphics
of a "network graphics language". But the class hierarchy could be 
expanded, and grown, to include other classes of rendering objects. 
The language syntax could be more abbreviated to make program size 
smaller. The viola objects abstraction could be raised to improve 
cross platform portability. Viola could be ported to other platforms.
Security could be better improved without giving up too much flexibility
(currently every object has a security tagging, and all objects 
instantiated from foreign sources are marked as untrusted to system 
priviledges...). etc.

                                        Pei Y. Wei  (
                                        O'Reilly & Associates, Inc.

PS. you might want to forward this to the original To:list. My machine
    ran out of machine id spots, it said.