[opensource-dev] Client-side scripting in Snowglobe

Morgaine morgaine.dinova at googlemail.com
Fri Feb 19 07:23:53 PST 2010

Indeed Rob!

Lua is a brilliant language for adding scripting to existing applications
--- it's designed expressly for embedding and extending, it has a clean
syntax, it is linguistically very powerful, it is very tiny (the whole thing
can add under 100KB to your application), it can run sandboxed or not as
desired, and it is one of the fastest pure scripting languages currently
available, a lot faster than say Python.

It is no surprise then that game developers worldwide flocked to it in
droves, and now it's one of the most common scripting languages found
embedded in games.  WoW fans use it daily as an intrinsic part of their WoW
client, and a huge community has grown up around Lua-powered interfaces for
that game.

So yes, I'm with you on the importance of Lua for client-side scripting of
the viewer.

However, advocating Lua as the sole means of scripting viewers would be just
as bad a mistake as advocating C# or CLR-targetted languages only.  It would
support only one part of the scripting community directly, while
discriminating against everyone else.  This is not necessary.

Instead, defining a socket-based API interface would allow effectively any
language to be used for scripting the viewer, since virtually all languages
today have socket capabilities.  That would certainly include Lua and C# and
Python and Perl and Java and Clojure and C/C++ and ObjectiveC and Smalltalk,
to name a few languages that this community uses regularly.

The only thing that we would have to agree on would be the set of messages
that cross the socket interface, and the set of functions and callbacks that
the messages would engage in the viewer.  That's the kind of productive
technical discussion we could be having with Lindens, if their design
process for client-side scripting were open.  It needs to be.



On Fri, Feb 19, 2010 at 5:24 AM, Rob Nelson <nexisentertainment at gmail.com>wrote:

> B-B-But what about Lua, which has already been implemented in FlexLife
> (http://flexlife.nexisonline.net)? :(
> Fred Rookstown
> Lead Developer
> On Thu, 2010-02-18 at 12:42 +0000, Morgaine wrote:
> > I referred recently to Linden's internal project "Firefly" to add
> > client-side scripting to SL viewers.  This has been the topic of open
> > discussion at several Office Hours with Lindens in SL, but that
> > openness has not extended to many design details --- the Firefly
> > design process is not open to the community.  The only technical
> > details that are being disclosed about Firefly appear to be:
> >
> >       * "Scripts" are actually Mono assemblies, so that only languages
> >         that compile to Mono will be allowed.
> >       * The programs run in a sandbox, which means that most platform
> >         resources are not accessible to them.
> >
> > Please note that I quite like C# as a language, but the following
> > remarks are about Mono use in the SL viewer, only, where its tradeoffs
> > are poor.
> >
> > The first known detail about Firefly (mandatory Mono) is problematic
> > on several fronts:
> >      1. Only a tiny fraction of the world's applications, libraries
> >         and languages work on Mono, so client-side scripting will be
> >         unable to benefit from the huge mountain of resources
> >         available on the Internet.  This is an extremely severe
> >         limitation, and an unnecessary restriction in the context of
> >         client-side viewer scripting.  If I want to use a
> >         locally-installed package X from within my client-side script,
> >         I should be able to.  What runs client-side should always be
> >         our individual choice, not someone else's.
> >      2. Programmers want to write client-side scripts in the language
> >         that they know best, because that always yields the fastest
> >         progress and highest quality results.  There was a good
> >         technical reason for forcing everyone to use LSL server-side,
> >         but there is no technical reason to impose this requirement on
> >         all client-side scripting.  It is counter-productive to force
> >         CLR compatibility on client-side script developers when there
> >         is a simple alternative:  define a socket-based viewer API for
> >         client-side scripts instead, hence usable from any language.
> >      3. Mono runs poorly on Linux, so from being rock-solid on Linux
> >         now, the LL-derived viewers will become second-rate on this
> >         platform.
> >      4. The viewer is already extremely bloated and a memory hog.
> >          Adding a Mono dependency will compound that horribly.
> >      5. There is only one effective supplier of Mono:  Novell.  That
> >         is a very bad situation to encourage and to support in the
> >         viewer.
> >      6. Some parties identify other reasons for avoiding Mono in
> >         general.  Without getting into that subject at all,
> >
> > The second known detail about Firefly (mandatory sandbox) is
> > problematic on two related fronts:
> >      1. Sandboxes by design do not allow most platform resources to be
> >         accessed, as a security measure.  This is fine and important
> >         when scripts are being downloaded from unknown places (like
> >         Javascript in web pages), but that same protection also means
> >         that client-side scripts would be powerless to do useful
> >         things for us in concert with local applications, files,
> >         devices, etc.  Sandboxing client-side scripts effectively
> >         hardwires in script weakness for no reason discussed as a
> >         requirement.
> >      2. Sandboxed applications cannot be linked with user-chosen
> >         native libraries since allowing native code breaks sandbox
> >         protection.  This means no accelerators, no extensions, and no
> >         interop with other systems since sockets are inaccessible from
> >         any strong sandbox.  This also means no evolution or progress
> >         outside of what the sandbox designers permit.
> >
> > This mailing list is concerned with development of open source
> > viewers, in particular Snowglobe.  This is heralded as a community
> > viewer, embodying community requirements much more directly than the
> > LL mainstream viewer.  Client-side scripting will impact on every
> > single aspect of Snowglobe bar none, yet the community is being
> > excluded from the design of its most powerful infrastructure element.
> >  This is entirely wrong, far beyond the normal observation
> > that secrecy in design has no place in open source.
> >
> > It is hard to assess things technically when the design requirements
> > are formulated in secret.  The Snowglobe community has design
> > requirements too.  Those deserve to be examined here openly, not
> > limiting Snowglobe to a design that stems from Linden requirements
> > alone.
> >
> >
> > Morgaine.
> >
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