Around 14 o'clock on Mar 5, Alexander Gelfenbain wrote:

> There is nothing in STSF architecture that makes it client-side or
> server-side. It can be either or both. ST Font Server / ST Client Library
> client-server model has nothing to do with X11 client-server model. ST
> architecture defines that both ST Client Library and ST Font Server should
> always reside on the same machine and communicate via the fastest protocol
> available (UNIX sockets, Solaris doors, or whatever.)

I don't think this is completely accurate.  If you can learn anything from
the experiences that 17 years of deployment among dozens of existing X
applications can teach, you'll see that whatever API you create will be
insufficient for some non-trivial set of applications.  

The ST API may solve 90% of the problems for applications, but failing to
provide for that additional 10% means that we'll continue to have
applications working around the existing font infrastructure rather than
cooperating with it.

A well designed client-side API would permit applications to take 
advantage of most of the available font services while replacing those 
inappropriate for their system, sharing configuration and customization 
data along with rendering infrastructure and other subsystems.

> In its client-side mode STSF can act as a replacement for Xft. The
> server-side implementation of STSF - XST is an X11 extension implementation
> of STSF API.

Xft provides functionality which is isomorphic to STSF -- STSF would be
implemented on top of Xft instead of as a replacement.  All that Xft does
is connect the standard XFree86 glyph rasterizer API (FreeType) to the X
server.  Xft provides a useful abstraction by eliminating any dependency on
the Render extension for client-side text, it doesn't perform any text 
layout or font selection.

> We would like not to get into client-fonts vs server-fonts flamewar and
> would prefer to concentrate on discussing the usefulness and the
> sufficiency of ST API for modern applications, be it implemented on the
> server side or on the client side.

As we've seen through the years, any API we design for text will be
insufficient for some significant class of applications.  Any new text API
must initially be judged in how well it will work with applications that
aren't satisfied by it's capabilities.  A server-side ST architecture is no
better than the core X protocol in that regard.

A transparent client-side implementation of an ST-like system would have a
fundementally different API architecture than what you've proposed today.
Any discussion on the current API cannot usefully proceed in the absence of
concensus on this issue.

Keith Packard        XFree86 Core Team        Compaq Cambridge Research Lab


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