Re: Keeping HTML Simple & Format negotiation between Browser & Server

Tony Sanders <>
Message-id: <9305272008.AA26764@austin.BSDI.COM>
Subject: Re: Keeping HTML Simple & Format negotiation between Browser & Server 
In-Reply-To: Your message of Thu, 27 May 93 14:24:29 CDT.
Organization: Berkeley Software Design, Inc.
Date: Thu, 27 May 1993 15:08:29 -0500
From: Tony Sanders <>
Keep it simple being the key phrase:

> Each link in the image would consist of:
>  -  a union of rectangles designating the boundary of the link
>  -  a URL
>  -  a set of flags, perhaps including one indicating whether the link
>     should be decorated by the browser, or whether the link is already 
>     decorated in the image
My prefered scheme for selection of links in external objects is just send
the x,y coordinates of the selection to the server and let it deal with
it however is best.  This is how the current selection stuff works for
<IMG ISMAP>.  This lets you backend with whatever you need (like maybe
WAIS spatial indexing) without hardcoding anything in the client.

This scheme has the advantages of being easy on the browser, simple to
implement, low network overhead, it fits in with the existing HTTP
protocol (even HTTP/0.9) and it's working today:
	Is a demo of exactly this scheme (requires Mosaic 1.0 with the
	patches pointed to in the document, Mosaic 1.1 will have this
	built-in).  Text-only browsers need to start doing something about
	<IMG> like [Sorry, image not available].
	Is another demo of image selection with a pratical side.

The HTML looks like:
    <A HREF="http://server/path><IMG SRC="..." ISMAP></A>
and upon selection the browser sends:
where x and y are simply the mouse coords (or whatever) relative to the
image origin (prior to any mucking around by the browser like scaling).
If the browser doesn't support ISMAP then the URL http://server/path is
sent just like normal and the server would simply return a normal HTML
document that has textual anchors for each item you can select from the

The same scheme could work for any external format with a little
cooperation from the viewer.