[vos-d] thoughts and plans

[Peter Amstutz]

I've been quiet, but that doesn't mean I haven't been thinking about VOS 
development.  I'll try to describe some of the things I've been working 
on recently.

Most importantly, starting July 9th, I will be devoting half of my time 
(2-3 full days each week) to VOS development.  Coding, which has been 
stalled for awhile, will resume at that point.

In the mean time, I have been fleshing out various s5 design details in 
my mind.  The main subjects have been:

 - Scalability, clustering and recovery from failure.  The general ideas 
is to use replication for load balancing and distributed locks for 
consistancy control.

 - Programming with continuations as a way of supporting concurrency 
without requiring threads.  Also how to emulate continuations in 
languages that don't support them!

 - Authorization-based access control using object capabilities.  I am 
still planning to write an email discussing capability security in VOS.

 - User interface for the 3D client.  This is a critical issue on which 
we have spent too little time in the past.  

Let me talk a little bit about the last part.  This time around, I'm 
going to try and have a prototype 3D client in place even before we've 
finished writing the core.  That way, we have (hopefully) something 
people can play with while development of the underlying network object 
model proceeds.

I've spent a little while thinking about the interaction mode of the 
client, and came up with a few basic principals to follow:

 * It must be very open-ended.  The goal is for the application to be 
able to configure itself to different task, be it a 3D game, social 
space or business purpose.

 * It should be usable by both novices who want a minimal browsing 
experience, and experts who are engaged in scene editing or development.

 * It should be designed to permit plugins or extensions to its 
functionality.

The model we have been using up until now has been the web browser, but 
it occurred to me that although familiar, this may not be the right 
model.  Now, what is a highly popular application that is suitable for 
both viewing and editing, and is open ended...  I think the right model 
is Emacs!

I've put together a mockup screenshot here:
http://interreality.org/~tetron/terangreal%20mockup.png

At the top, like a web browser, you have the current URL (a vobject) 
which you are interacting with.

In the upper right corner, you have the "major mode" which defines how 
what type of interface to use to present the vobject.  For a 3D scene, 
you might have a "navigation" major mode used for normal browsing and 
chatting, a "construction" major mode which provided controls for adding 
objects and moving objects around.  If you clicked on a mesh, you could 
go into an "editing" major mode which allowed for editing polygons and 
vertices of an individual mesh.  If you selected a material, you could 
go into a "material" mode for editing the material properties.

In addition to these specialized modes, you would have generic major 
modes, such as presenting a hierachical tree view of the vobject 
structure, or editing text properties.

Additional major mode could embed a web browser or other document 
viewers and editors, operating on resources stored in Vobjects or on the 
web.  Ultimately, the system should be entirely reflexive, so that the 
user interface is itself described using VOS; this would allow creating 
both 2D and 3D applications within the platform.

The major mode broadly defines how a particular vobject tree is 
presented to the user and provides a base set of key and mouse bindings.  
In addition to this, you have minor modes and tools.

A "tool" would be a piece of code which can be bound to a key or mouse 
action.  It might operate on the currently selected item, ask the user 
for input, or just execute some action.  The major mode would specify a 
base set of tool bindings.  A tool would be somewhat similar to an Emacs 
interactive function, in that new tools could be defined on the fly and 
would operate on the current environment.  Tools which only worked with 
the underlying vobject would also be usable across different major 
modes, enabling the user to reuse the same commands even with entirely 
different frontend interfaces.

A "minor mode" would be a set of key or mouse bindings that is overlayed 
on the current major mode.  Usually, the user would enter a minor mode 
by using a tool.

For example, the user wishes to grab and rotate a 3D object.  The use 
the "rotation" tool.  This invokes a "rotation" minor mode which changes 
the mouse bindings to allow the user to click and drag to rotate the 
object in question.  When the user is done, the "rotation" minor mode 
removed and the previous mode is restored.

Under this design, a 3D game would supply a minor mode providing a 
complete set of key bindings to the game controls, such as binding the 
number keys to "tools" which cast spells.

In short, I'm envisioning a sort amalgamation of Firefox, Emacs and 
Blender, possibly with some Visual Studio-style detachable "pop-out" 
windows (using wxAUI) thrown in for good measure.

It's crazy, but it just might work.

-- 
[   Peter Amstutz  ][ tetron at interreality.org ][ peter.amstutz at gdit.com ]
[Lead Programmer][Interreality Project][Virtual Reality for the Internet]
[ VOS: Next Generation Internet Communication][ http://interreality.org ]
[ http://interreality.org/~tetron ][ pgpkey:  pgpkeys.mit.edu  18C21DF7 ]

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