Re: How about a Safe Virtual Machine?

Nathaniel Borenstein (
Tue, 4 Oct 1994 22:27:49 +0100

Excerpts from www-talk: 4-Oct-94 Re: How about a Safe Virtua.. "Daniel
W. Connolly"@hal (2248)

> I'm a little bit confused when you say that Tcl will only be used for
> these little user dialogs, and then you also say that the way to
> extend the system is to distribute add on modules, presumably in Tcl:

Well, there's two separate issues here. As far as the "right" way to
distribute it, yes, they are add-on modules, written in Tcl, and this is
an example of why Tcl needs to be extended to support modules with
separate name spaces. I believe this is part of the development plan
for Tcl anyway. So what I'm saying is that most programs will
*probably* be small, but that extension packages will need Tcl extended
with modules, which is probably coming in any event. When it does come,
it will make a lot of this discussion moot, as programming-in-the-large
with Tcl will be a lot less painful.

> By the way... I hope that authentication of modules is in the works...
> I'd hate to have somebody forge a Safe-Tcl add-on module by attacking
> DNS or whatever.

Secure DNS is one of the few areas of Internet security research that I
believe is truly important.

> Hmmm... if we agree that Safe-* is only for "RPC with humans" and that
> hence Safe-Tcl is sufficient for Safe-Tcl, the next step is to see how
> Safe-Tcl integrates with distributed object technologies like HTTP,
> CORBA, ILU, DCE, etc. that will be used to build the "guts" of these
> CSCW applications. Hmm... there are Tcl bindings for Modula-3...
> playing with that should keep me busy for a few late nights...

If you change "only" to "mostly", I don't have any problem with that
paragraph. I'd like to think of Safe-Tcl as the "glue" that lets one
person's Scheme-based server talk to another person's Python-based
server and to reach out and ask questions of human users when
appropriate. A lingua franca for the Internet. It's a nice metaphor,
actually, because what you look for in a "lingua franca" is simplicity
and ease of learning/implementation, even at the possible expense of
some expressive power or elegance. I'm reminded of that every time I go
someplace like Mexico and see a Japanese tourist communicating with the
locals in simplified English.